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NeuroImage 37 (2007) 361 – 378
Resolving sentence ambiguity with planning and working memory
resources: Evidence from fMRI
Susana Novais-Santos, a James Gee, a,b Maliha Shah, c Vanessa Troiani, c
Melissa Work, c and Murray Grossman c,⁎
a
Department of Bioengineering, University of Pennsylvania, USA
Department of Radiology, University of Pennsylvania, USA
c
Department of Neurology-2 Gibson, University of Pennsylvania School of Medicine, 3400 Spruce St., Philadelphia, PA 19104-4283, USA
b
Received 16 December 2006; revised 24 February 2007; accepted 14 March 2007
Available online 13 May 2007
We used functional magnetic resonance imaging (fMRI) to test competing claims about the role of executive resources during the disambiguation of a sentence featuring a temporary structural ambiguity.
Written sentences with a direct object (DO) structure or a sentential
complement (SC) structure were shown to 19 healthy, right-handed,
young adults in a phrase-by-phrase manner. These sentences contained
a main verb that is statistically more likely to be associated with a DO
structure or an SC structure. Half of each type of sentence also
contained an extra phrase strategically located to stress working
memory prior to disambiguating the sentence. We found that sentences
featuring a less consistent verb-structure mapping recruit greater
dorsolateral prefrontal cortex (dlPFC) activation than sentences with a
more consistent verb-structure mapping, implicating strategic on-line
planning during resolution of a temporary structural ambiguity. By
comparison, we observed left inferior parietal cortex (IPC) activation
in sentences with an increased working memory demand compared to
sentences with a low working memory load. These findings are
consistent with a large-scale neural network for sentence processing
that recruits distinct planning and working memory processing
resources as needed to support the comprehension of sentences.
Published by Elsevier Inc.
Keywords: Sentence comprehension; Executive; fMRI; Prefrontal; Parietal
Introduction
Unraveling the complex neural substrate underlying the human
language comprehension system has been a major goal of neuroscience during the past century. Recent observations emphasize
⁎ Corresponding author. Fax: +1 215 349 8464.
E-mail address: [email protected] (M. Grossman).
Available online on ScienceDirect (www.sciencedirect.com).
1053-8119/$ - see front matter. Published by Elsevier Inc.
doi:10.1016/j.neuroimage.2007.03.077
that executive resources play a substantial role during sentence
comprehension. This has led to a two-component model of sentence
processing that distinguishes between core sentence processing
mechanisms and executive resources like working memory and
strategic planning that support sentence comprehension (Friederici,
2002; Wingfield and Grossman, 2006). From this perspective, the
core sentence processing mechanism in left peri-Sylvian cortex
recruits resources such as working memory (WM), planning/
switching and selective attention as needed. These resources are
supported in other, non-peri-Sylvian brain regions. The present
study uses functional magnetic resonance imaging (fMRI) to examine this model during the comprehension of sentences with a
temporary structural ambiguity.
Functional neuroimaging studies of syntactic processing have
shown activation of core peri-Sylvian language areas, namely left
inferior frontal (IFC) and posterolateral temporal (PLTC) cortices,
during tasks such as grammaticality judgments and answering
probes about complex sentences (Ben-Shachar et al., 2004; Cooke
et al., 2006; Cooke et al., 2001; Kuperberg et al., 2003; Ni et al.,
2000). Experimental factors such as the modality of sentence presentation (visual or auditory) (Caplan et al., 1999; Friederici et al.,
2000; Michael et al., 2001), the type of response (comprehension or
expression) (Indefrey et al., 2001) and the age of the subjects
(Caplan et al., 2003; Grossman et al., 2002) introduce subtle
differences in the location of peak neuroanatomic activation, but
over-all the results consistently emphasize the contribution of periSylvian frontal and temporal regions of the left hemisphere during
sentence processing.
The mental representation of an unfolding sentence appears to
be constructed incrementally, moreover. As each successive word is
encountered in this first-pass analysis, it is rapidly integrated into an
evolving interpretation. Some have referred to this as the principle
of “minimal attachment” (Ferreira and Henderson, 1991; Frazier
and Rayner, 1982). However, this is not a straightforward task, as
the syntactic and thematic relationships between a word and the
remainder of the sentence are often undefined when that word is
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first encountered, and can be specified only after additional material
from the sentence has emerged. The process of sentence construction can be studied by examining the resolution of a temporary
structural ambiguity. Consider a sentence like “The citizens heard
the election result was fixed.” As this sentence emerges over time,
for example, a listener is likely to interpret “the election result”
initially as the direct object (DO) of “heard.” However, as the
sentence is completed, it becomes apparent that “the election result”
is the subject in a sentential complement (SC) that includes the verb
“was fixed.” While it is possible to disambiguate a sentence by
inserting the complementizer “that” (e.g. “The citizens heard that
the election result was fixed”), text corpora statistics show that such
complementizers are commonly omitted (Elsness, 1984; McDavid,
1964; Thompson and Mulac, 1991).
Recent reviews have identified two main theories of syntactic
processing: Parallel processing, which emphasizes working memory, and serial processing, which emphasizes on-line decisionmaking (Gibson and Pearlmutter, 2000; Lewis, 2000). The parallel
processing approach posits that, when parsing a sentence, we build
multiple representations of all possible sentence structures, and
maintain them in WM. According to this theory, we compare the
alternate constructions in WM and then interpret the sentence by
choosing the most plausible structure (Earley, 1970; Gibson, 1998;
Gibson and Pearlmutter, 1998; Gibson and Pearlmutter, 2000;
Jurafsky, 1996; Just and Carpenter, 1992; MacDonald et al., 1994;
Pearlmutter et al., 1999; Spivey and Tanenhaus, 1998; Stevenson,
1994). Mason et al. (2003) found experimental evidence for this
parallel method of sentence processing in their fMRI study of ambiguous sentences. They observed higher levels of brain activation
in left IFC and left PLTC when an ambiguous sentence is resolved
in favor of either the preferred (more probable) or the unpreferred
(less probable) interpretation, as compared to an unambiguous
sentence. The authors explain their findings on the basis of a ranked
parallel model, which always consumes massive WM resources
during sentence disambiguation, since all possible structural
interpretations must be constructed and temporarily maintained in
an active state regardless of sentence type. A similar conclusion was
reached on the basis of inferior frontal activation in a study that
assessed structurally ambiguous sentences in individuals with high
and low WM spans (Fiebach et al., 2005). The IFC component of
verbal WM has been associated with a rehearsal mechanism
(Jonides et al., 1998; Smith and Jonides, 1998a,b). Other work with
unambiguous sentences has shown that, in the course of sentence
processing, WM demands are also supported by a phonological
buffer associated with inferior parietal cortex (IPC) (Cooke et al.,
2006; Fiebach et al., 2001; Grossman et al., 2002; Stowe et al.,
1998).
The second processing approach uses on-line planning and subgoal decision-making to disambiguate sentence structure, based on
the probabilistic information conveyed by lexical biases in the sentence (Ferreira and Clifton, 1986; Ferreira and Henderson, 1990;
Garnsey et al., 1997; Traxler et al., 1998; Trueswell et al., 1994;
Trueswell et al., 1993). The temporary structural ambiguity of the
sentence “The citizens heard the election result was fixed” is set up
by the fact that the verb “heard” is biased statistically in its more
frequent association with a DO sentence structure, even though it is
embedded in this instance in a sentence with an SC structure. By
comparison, the sentence “The citizens claimed the election result
was fixed” is less likely to evoke a garden path interpretation since
the verb “claimed” is associated more often with an SC type of
sentence structure. This kind of lexical bias can be used on-line to
anticipate the most likely sentence structure. While the parallel
method computes and maintains all possible parses, the serial
approach only follows the most probable one. This leads to reduced
WM demands, but at the cost of greater decision-making and
planning. Serial models access the mental lexicon to obtain a broad
range of information about the words being encountered, including
lexical bias (Garnsey et al., 1997), semantic plausibility and pragmatics (Traxler et al., 1998), in order to determine the most probable
interpretation, which is then pursued. For example, in an experiment investigating the DO/SC ambiguity with a word-by-word
self-paced reading task, Holmes (1987) observed that readers were
clearly led astray in case the unfolding sentence structure did not
meet their expectations. Subjects used information provided by the
verb bias, as well as the plausibility of the nominal phrase as a direct
object, in order to choose what interpretation to follow. In contrast,
in parallel accounts of sentence processing, when the reader
encounters a word, all of the semantic primitives associated with the
word receive some activation (Traxler et al., 1998), which activates
all possible structure interpretations, regardless of context and specific lexical properties of sentence constituents. The serial account
of sentence processing thus results in increased costs of decision
making, as a decision has to be made regarding what interpretation
to follow.
Non-linguistic studies of planning and switching implicate
dorsolateral prefrontal cortex (dlPFC) (Braver and Bongiolatti,
2002; Paulus et al., 2001; Rowe and Passingham, 2001; Savage et
al., 2001; Seger et al., 2000; Smith et al., 2001; Sylvester et al.,
2003). In one study of ambiguous sentence processing, basal
ganglia activation was reported (Noppeney and Price, 2004), an
area frequently co-activated with dlPFC as part of a fronto-striatal
loop that may play a role in error detection (Ullsperger and von
Cramon, 2006). However, previous imaging assessments of
structural disambiguation have not systematically evaluated the
role of verb biases and probabilistic decision-making during
sentence processing. In the present study, we investigate whether
these same resources are used in association with linguistic
tasks.
To achieve our goal, we modified the materials of Garnsey et al.
(1997) to examine the role of verb bias and WM load on sentence
interpretation. We manipulated the compatibility between sentence
structure and verb bias, on the one hand, and we also inserted
additional, strategically placed material to stress WM independently
of grammatical structure in half of the sentences of each type.
Moreover, our behavioral technique during fMRI scanning minimized task-related resources that could confound interpretation of
the results, since subjects passively viewed grammatically correct,
semantically coherent written sentences presented in a phrase-byphrase manner. We hypothesized greater frontal recruitment during
sentences with a temporary structural ambiguity. This may be due to
increased IFC activation for all sentence types if their interpretation
depends on WM. Alternately, dlPFC activation may be seen under a
condition of low consistency between a verb and its sentence
context, relative to high consistency between a verb and its sentence
context, if planning and decision-making contribute to the
resolution of a temporary structural ambiguity in a sentence. Moreover, we expected left IPC activation associated with the WM
component of sentence processing, regardless of the type of
sentence. We acknowledge that WM is always needed to read
sentences. However, in this study, we are measuring differences in
relative WM load rather than absolute values. We operationalize
WM by including the additional phrase and predict IPC activation
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
under conditions of relatively higher WM load. Such observation
will allow us to infer that IPC is a neural resource for WM, which is
activated when there is a relatively higher demand for WM.
Methods
Subjects
In our behavioral study we tested 20 young (4 males and 16
females), healthy adults, matched for age and education (mean
(± SD) age = 21.4 (± 0.5) years; mean (± SD) education = 15.0
(± 0.05) years) with the imaged subjects. For the imaging experiment, 19 volunteers (13 males and 6 females, aged 18–30 (mean
(± SD) = 20.8 (±0.5) years), education level 13–21 years (mean
(± SD) = 15.6 (± 0.5) years) were scanned. All participants were
right-handed native English speakers. All subjects were young and
healthy, and were screened medically in order to insure they were
not taking any psychoactive medications and had no neurologic or
psychiatric disorders. Each subject participated in an informed
consent procedure approved by the Institutional Review Board
(IRB) at the University of Pennsylvania.
Materials
In this experiment, we manipulated the type of sentence structure, the syntactic bias associated with the main verb of a sentence,
the syntactic bias associated with the post-verbal noun, and the
working memory demands associated with these materials.
Sentence structure
The sentence type is determined by the syntactic frame in which
a verb and the other words of a sentence are embedded. Sentences in
our experiment had either an SC structure or a DO structure. For
example, consider the following:
1. The worried friar asserted the belief would be justified (SC).
2. The diligent disciple asserted the belief readily (DO).
Sentence 1 has an SC structure, whereas sentence 2 has a DO
structure. In the former, the verb “asserted” is followed by the
sentential complement “the belief would be justified.” In this case,
“the belief ” is the head noun of that subordinate clause. In the latter
sentence, “the belief ” is the direct object of the verb. The entire set
of sentences is presented in Appendix A.
Verb category
Verbs are biased statistically to occur with a varying probability
in one of these sentence contexts. Some verbs are more likely to be
used in sentences in which they are followed by a direct object, and
are hence more often encountered in a DO structure. For instance,
the verb “assert” normally entails an object being asserted and is
thus found more frequently in sentences of the type “The honest
witness asserted the truth forcefully” than in sentences like “The
honest witness asserted the truth was important.” A DO verb can
nevertheless occur in an SC structure without disturbing sentence
coherence. By comparison, other verbs are seen more commonly in
sentence constructions that contain a sentential complement and
thus have an SC statistical bias. For example, one is more likely to
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encounter the verb “prove” in a sentence with an SC structure such
as “The gifted lawyer proved the argument was unfounded” than in
a DO structure like “The gifted lawyer proved the argument.” SCbias verbs can occur in a DO sentence structure without disturbing
sentence coherence as well. Finally, we also used a class of verbs
without a sentence bias, having an equal probability of appearing in
a DO sentence or an SC sentence. This is to diminish the possibility
that subjects would explicitly detect that a subset of the verbs have a
structural bias that is less compatible with the syntactic structure of
the sentence. For instance, the verb “acknowledge” falls into this
category, since it is associated as often with a DO structure like
“The sales clerk acknowledged the error honestly” as with an SC
structure like “The sales clerk acknowledged the error was minor.”
We refer to this as an EQ-bias verb.
Verbs were classified as SC-biased if they were found at least
twice as often with an embedded sentential complement as with a
direct object. The reverse was true for verbs categorized as DObiased. Verbs were classified as EQ-biased if they occurred approximately equally often with sentential complements and with direct
objects (with a difference not greater than 15%). We based our
choice on the verb ratings produced by Connine et al. (1984) and on
their frequency of occurrence. For this experiment, we selected 10
verbs of each type. The three sets of verbs differed in SC-bias
(F(2,45) = 29.38, Mse = 276, p b 0.01) and in DO-bias (F(2,45) =
91.26, Mse = 173, p b 0.01). The mean preference strength of each
type of verb towards each completion is summarized in Table 1. The
three sets of verbs did not differ significantly in letter length (F = 2)
or frequency of occurrence (Francis and Kucera, 1982) (F = 1). The
post-verbal noun was selected so that any bias was equally
distributed over each verb–sentence structure relationship. Some
verbs of each type were chosen to be polysemic, i.e. to have more
than one meaning. For instance the verb “maintain” is used both in
the sense of providing maintenance (“maintained the machinery”)
and of holding an opinion (“maintained the machinery was
obsolete”). The number of polysemic verbs is low and equally
distributed over verb types (two polysemic verbs of type DO and
two of type SC). The entire set of verbs is presented in Appendix B.
All six combinations of verb–sentence structure are grammatically correct and semantically coherent. They appear with equal
frequency in our set of materials, hence giving rise to moreconsistent or less-consistent stimuli: verbs of type DO are more
consistent with a DO sentence context and less consistent with an
SC sentence structure; SC-biased verbs are more consistent with an
SC sentence frame and less consistent with a DO sentence context;
and EQ verbs are equally consistent with both DO and SC sentence
structures, and were thus considered as belonging to the same
category as the sentential context in which they were embedded.
For analytic purposes, we treated these as “more consistent” stimuli.
Table 1
Mean (±SD) preference strength of each type of verb towards each
completion
Verb bias
Completion
Mean (± SD)
preference strength
SC
DO
SC
DO
EQ
EQ
SC
DO
DO
SC
DO
SC
0.74 (0.09)
0.71 (0.14)
0.15 (0.10)
0.13 (0.07)
0.41 (0.08)
0.45 (0.10)
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S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Noun category
Another relevant factor in our study is the plausibility of the
post-verbal noun phrase as a direct object in the particular sentence
under consideration. Similarly to verbs, nouns also have varying
affinities for appearing in direct object contexts and sentential
complement contexts. Consequently, the choice of the post-verbal
noun in a sentence with a temporary structural ambiguity can
greatly influence the initial interpretation of the sentence. For
instance, the noun “money” is far more plausible as a direct object
of “accepted” than the noun “fire” in the following DO-type
sentences: “The talented photographer accepted the money” vs.
“The talented photographer accepted the fire”. Likewise, in an SCtype sentence containing a DO-biased verb, the type of post-verbal
noun has a considerable influence on the sentence interpretation.
For example, the sentences “The talented photographer accepted the
money was spurious” and “The talented photographer accepted the
fire was hazardous” have the same structural frame (SC); however,
the particular choice of noun biases their interpretations in slightly
different directions. As was done for sentence and verb type,
materials were designed so that noun types were also matched for
frequency. Half of the nouns used in the study had an SC bias and
the remaining a DO bias.
Noun classification (SC or DO) was based on their plausibility as
direct objects of each verb. Garnsey et al. (1997) determined noun
plausibility with a norming study, in which subjects were asked to
rate sentences like the following on a 7-point scale (7 = very
plausible): “The senior senator regretted the decision” and “The
senior senator regretted the reporter”. A high score would mean that
the post-verbal noun is a plausible direct object of its predecessing
verb. Nouns were categorized as more or less plausible direct objects
(thus, DO or SC) if they met the following criterion: The difference
in ratings between the more plausible and less plausible direct object
version for each verb was at least 2.5 on the 7-point scale.
We based our choice on the noun ratings produced by Garnsey et
al. (1997). For this experiment, we selected 60 nouns, 30 of each
type (DO or SC). The choice of nouns in Garnsey et al. (1997) was,
however, not completely suitable for our purposes. In our study, we
want to address the processing of sentences with temporary
structural ambiguities. These ambiguities often emerge due to an
inconsistency between the noun type and the sentence frame in
which it is embedded. Therefore, if the noun is clearly SC- or DObiased, such ambiguity may not occur altogether. We thus had to
change some of the post-verbal nouns (18 in total) provided by
Garnsey et al. (1997), as they were not ambiguous enough to
generate the garden path effect. For instance, we had to change one
of the nouns following the verb “declared”. In the original version,
the two sentences were as follows: “The new mayor declared the
holiday would be a festive occasion” and “The new mayor declared
the potholes would be repaired in June”. In this case, the post-verbal
noun “the potholes” does not raise a temporary structural ambiguity,
since it obviously cannot be the direct object of the verb “declared”.
The reader immediately understands that it is, rather, the subject of
an unfolding sentential complement structure. There is, consequently, no garden path effect. We used a different post-verbal
noun, in order to create a DO/SC ambiguity. The 18 nouns we
introduced into the study were also rated for plausibility, following
the aforementioned norming method, by a group of 15 (3 males and
12 females) healthy, young (aged 22–27, mean (±SD) = 24.5 (± 0.5)
years) native English speakers. In order to avoid priming and
familiarity effects, which could have emerged in case part of the
materials had been disclosed to the participants prior to the study,
we asked a separate group of subjects to perform this rating. Nouns
did not differ significantly in length (Fs b 1) or frequency of
occurrence (Fs b 2). The whole set of nouns, along with their postverbal plausibility ratings, is presented in Appendix C.
Working memory
Half of each type of sentence had an additional WM component.
In order to make subjects retain information about the verb and the
post-verbal nominal phrase in memory for a longer period of time
before sentence structure is resolved, we inserted an extra WM
phrase between the post-verbal nominal phrase and the last
(disambiguating) phrase. We opted for inserting the WM phrase
just prior to disambiguation, as opposed to an earlier location within
the sentence, such as between the verb and the noun, in order to
avoid confounds that could thereby emerge from disrupting the
verb–noun structure.
Experimental procedure
In the present experiment we used the phrase-by-phrase method,
using a “moving window” display. This approach has been used
previously to assess sentence processing in cognitive (Just et al.,
1992) and imaging (Cooke et al., 2006) studies. Sentences were
presented to the subjects in a written, phrase-by-phrase manner, in
the following format: [initial-phrase] [verb-phrase] [noun-phrase]
([WM-phrase]) [concluding-phrase]. An example of sentence
presentation according to the experimental design is provided in
Table 2.
The sentence structure used in our experiment is as follows: the
first nominal phrase (the subject) always contains three words
(“the” + adjective + noun); the verbal phrase is always a verb in the
simple past (e.g. “confirmed”); the second nominal phrase (the postverbal noun) is always a two-word construct (“the” + noun); the
variable working memory phrase is a four-word long prepositional
phrase (e.g. “in upstate New York”); the last (disambiguating)
phrase consists of an adverbial phrase (e.g. “cheerfully”, “a thousand years ago”) or a brief verbal phrase (e.g. “were fair”, “was a
festive occasion”), the length of which (in syllables) was counterbalanced across conditions, so that it would not affect the results.
We used written materials to minimize the risk of biasing sentence
structural interpretation derived from oral prosody. The six types of
sentences were equally distributed in a random order over eight
blocks (30 sentences per block), and each verb appeared exactly
once in each block. Sentences were presented in a pseudorandom
order within each block. Sentence material was viewed passively to
Table 2
Example of sentence presentation according to experimental design a
Initial phrase
Verb
phrase
Noun
phrase
The diligent
disciple
The old nun
Asserted
The belief
Asserted
The belief
Optional WM
phrase
Concluding
phrase
Readily
In various
religious cults
Authoritatively
a
Example of two sentences used in our experiment, presented according
to the design. Both stimuli are “more consistent” (DO verb and DO noun in a
DO sentence frame). The first sentence is a stimulus “without WM”, whereas
the second is a stimulus “with WM”.
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
minimize task-related resources involved in decision-making. In
order to insure that the subjects were attending to the task and
processing the information, 20% of sentences in each block
(counterbalanced across conditions) were probed for a simple fact.
The random nature of these probes prevented the participants from
expecting a specific type of question and developing a strategy to
answer it, as we randomly probed different factual aspects of each
probed sentence. For example, the sentence “The rebelling
youngsters protested the policy fearlessly” was followed by the
probe “Did the rebelling youngsters protest the policy?”. Participants responded to such yes-or-no questions by a simple right- or
left-hand button press during the behavioral experiment or the
scanning procedure, immediately after the probe. These trials were
not excluded from the behavioral or functional analyses. As probes
always occurred after the sentence data had already been collected,
they did not interfere with that item. Therefore, insofar as our
experiment was concerned, probed items were no different from
unprobed items when they were read. We did exclude the probes
themselves and the responses to the probes.
In the imaging experiment each phrase was seen for a fixed 3-s
interval. The MRI scanner is equipped with stimulus delivery and
monitoring systems for fMRI research so that the sentence stimuli
can be presented to subjects while in the bore of the scanner and
responses to stimuli can be monitored. These systems include
Epson 8100 3-LCD projectors with Buhl long-throw lenses for rearview/rear-projection onto Mylar screens. The projector is housed in
a custom RF shield box with filtered power receptacles. Images are
viewed by the subject through mirrors mounted on the head coils.
Responses are monitored using FORP fiber optic button boxes. A
laptop computer outside the scanner room used E-Prime presentation software (version 1.1) to present stimuli and record response
accuracy.
In the behavioral experiment, materials were presented by a
laptop computer with E-Prime presentation software (version 1.1).
Subjects were instructed to press the space bar to advance through
the phrases of a sentence, and we monitored these latencies from the
onset of phrase presentation. Subjects were instructed to read each
sentence rapidly but carefully since we would be randomly probing
the content of some sentences. Subjects saw the phrase “GET
READY” on the screen at the start of the experiment, after which
the first phrase of the first sentence was displayed. A hash mark
(“#”) was shown for 3 s between stimuli, that is, between the last
phrase of a sentence and the first phrase of the subsequent sentence
in case there was no probe. If there was a probe question, that
separator appeared right after the probe and before the following
stimulus.
Imaging data acquisition and analysis procedure
This study was performed with a 3.0 Tesla Siemens Trio wholebody human MRI scanner at the Center for Advanced Magnetic
Resonance Imaging and Spectroscopy (CAMRIS) in the Department of Radiology of the University of Pennsylvania. We used a
standard clinical quadrature radiofrequency head coil. In order to
minimize and restrict head motion, firm foam padding was used.
Each imaging protocol began with MR structural scans to determine
regional anatomy: localizer images (TR = 20 ms, TE = 5 ms, 192 ×
192 matrix) and T1-weighted MPRAGE images (TR = 1620 ms,
TE = 3.87 ms, 192 × 256 matrix). BOLD fMRI monitored brain
activation during sentence presentation. A T2*-weighted echoplanar BOLD paradigm was adopted for acquiring functional
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images, with the following parameters: TR = 3000 ms, TE = 30 ms, a
rectangular FOV of 20 × 15 cm, flip angle of 90°, 3-mm slice
thickness and a 64 × 64 matrix, resulting in a voxel size of
3 × 3 × 3 mm. The data were analyzed off-line using SPM2 (Wellcome Department of Imaging Neuroscience). Each data set was
registered and aligned to the first image in the series, and the brain
volumes were normalized by registration to the T1 template (Evans
et al., 1993) of 305 averaged brain volumes (Frackowiak et al.,
1997) using a 12-parameter affine non-linear registration using 12
non-linear iterations and 7 × 8 × 7 basis functions. The volumes were
normalized to Talairach and Tournoux brain coordinates (Talairach
and Tournoux, 1988).
An event-related design acquired data for each phrase. Onset of
phrase presentation was synchronized with the scanner so that we
could acquire the onset of the hemodynamic response for each
stimulus presentation. By performing such synchronization, we
could accurately determine the BOLD effect elicited by the
presentation of each phrase. The fMRI time series was modeled
using a hemodynamic response function (HRF) with a temporal
derivative (Friston et al., 1998) and a time-to-peak parameter of 5 s.
Intrinsic temporal correlations were eliminated by estimating the
autocorrelation structure using a first order autoregressive model
(AR(1)) (Friston et al., 2000). We used a subtraction procedure in
our image analyses to isolate effects of interest. In particular, we
were interested in describing the activation pattern during the last
phrase of each sentence, where the temporary structural ambiguity
is resolved. To insure that the activation was due to the disambiguation process itself, rather than some other aspect of written
language processing, we subtracted the activation resulting from the
presentation of each initial, unbiased phrase of each sentence from
the activation associated with the terminal, disambiguating phrase
of each sentence. Subsequently, we contrasted these subtracted
activations across types of sentences to identify anatomical effects
associated with each hypothesized condition of interest. Since we
compared the terminal phrase across conditions after having
subtracted the initial phrase for each condition, we safely ruled
out the possibility of attributing some of the observed activation
patterns to linguistic wrap-up effects. A random-effects statistical
model (Penny and Holmes, 2003) was used that, first, performed the
contrast of activation associated with the terminal phrase minus the
initial phrase for each condition of interest in each subject. These
subtractions were then contrasted across conditions of interest
within each subject. Finally, these contrasts were examined across
individuals in a second-level analysis using a 1-sample t-test procedure. Using the SPM random-effects model (Holmes and Friston,
1998), we contrasted activation patterns such as “more consistent”
vs. “less consistent” stimuli and “high working memory” vs. “low
working memory” for the group. We provide contrasts with a height
threshold that is significant at the p b 0.001 level uncorrected,
corresponding to a z-score N 3.09, and an extent threshold of at least
20 voxels. Although relatively liberal, this significance threshold is
justified because we are contrasting activations that are controlled
by contrasts with an unbiased baseline (the initial phrase of the
sentence).
Results
Behavioral study
We found that the terminal phrase of a less consistent stimulus
takes longer to read than that of a more consistent stimulus (Table
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S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
3). No other reading time differences were found. We analyzed the
roles of temporary structural ambiguity and working memory
(WM) using an analysis of variance (ANOVA) with a consistency
(2: more-consistent vs. less-consistent) × WM (2: without additional WM phrase vs. with an additional WM phrase) design. Our
design contains two sentence types (DO and SC), three verb types
(DO, SC and EQ) and two noun types (DO and SC). However, in
our analysis, we have focused on the consistency between verb and
sentence, having thus reduced the first two factors (sentence and
verb types) to two conditions only: “more consistent” and “less
consistent”. The only other variable in the analysis is WM: “with
WM” and “without WM”. So, we only have four conditions (a 2 × 2
design).
There was a significant main effect for consistency [F(1,19) =
9.18; p = 0.007] (obtained by collapsing over WM variables, i.e.
“without WM” and “with WM” stimuli). We did not see a significant main effect for WM [F(1,19) = 0.84; p = 0.37] (measured
across consistency) or a significant interaction effect between WM
and consistency factors [F(2,19) = 1.53; p = 0.23]. There may have
been a difference between the imaging data and the behavioral data
because manners of presentation were not identical—whereas the
behavioral experiment used a self-paced moving-window presentation, in the imaging study all phrases were presented for 3 s. Even
though we found no effect for WM in the behavioral study, our a
priori hypothesis was that there might be a main effect for WM and
that consistency and WM might interact. Therefore, we contrasted
WM conditions within less-consistent and more-consistent stimuli.
This revealed a difference between “more-consistent, with WM”
and “more-consistent, without WM” stimulus types [t(19) = 3.33;
p = 0.004]. We also compared stimuli of the same WM type but
different consistency levels, and observed that there is a significant
difference between “more-consistent, without WM” and “less-consistent, without WM” stimulus types (p = 0.004), but not between
“more-consistent, with WM” and “less-consistent, with WM” stimulus types (p = 0.262). Accuracy in responding to probes was
comparable and very high for all stimuli (see Table 3).
fMRI activation study
Less-consistent stimuli were associated with dlPFC activation.
We compared cortical activation patterns elicited by “more consistent” stimuli with those resulting from “less consistent” stimuli.
The contrasts of the disambiguating phrase minus the initial, neutral
phrase for “more consistent” stimuli and “less consistent” stimuli
are illustrated in Figs. 1A–C, and the location and statistical attributes of the peak voxel in each cluster are summarized in Table 4.
We observed greater left dlPFC and bilateral IFC activation during
the disambiguating phrase for the “more consistent” stimuli (Fig.
1A), and bilateral dlPFC and bilateral IFC activation for the “less
consistent” stimuli (Fig. 1B). Fig. 1C and Table 4 also summarize
the direct subtraction of “less-consistent” minus “more-consistent”
conditions. This contrast showed activation in bilateral dlPFC.
Fig. 1. Activation for more consistent and less consistent stimuli1 and
activation for more WM minus less WM2. Note: 1. Distribution of activation
during the last phrase (relative to the first phrase) for stimuli in which verb
and sentence structure are “more consistent” (A) or “less consistent” (B).
Panel C depicts the contrast of these two conditions (“less-consistent” minus
“more-consistent”). 2. Distribution of activation during the last phrase
(relative to the first phrase) for the contrast of stimuli that contain an
additional WM phrase minus stimuli that do not contain an additional WM
phrase (D).
No areas showed higher activation levels for “more consistent”
than for “less consistent” stimuli. Percent signal change measurements for the activated regions, for both “more consistent” and “less
consistent” stimuli, are summarized in Table 5.
We also investigated more detailed effects in the sentence
materials unrelated to our main hypothesis, such as manipulating
the type of verb in itself, as well as the effect of manipulating the
Table 3
Mean (±SD) response latencies for more consistent and less consistent verb–sentence stimuli a
Stimulus type
Main effect
Without WM
With WM
Probe accuracy
More consistent
Less consistent
671.78 (±257.22)
704.64 (±254.98)
660.84 (±261.35)
703.66 (±266.80)
682.73 (±258.47)
705.63 (±246.50)
95.33 (±7.83)
91.36 (±7.31)
a
Results for main effect (first column) were obtained by collapsing over WM variables (“without WM” and “with WM” stimuli). Results for “without WM”
and “with WM” columns were obtained by measuring latencies separately for each condition. Latency values are in ms. Probe accuracy is percent correct.
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Table 4
Neural activation patterns for more consistent and less consistent stimuli
Contrast
More consistent
a
Less consistent a
Less consistent−more
consistent b
Activation
locus
Brodmann
area (BA)
Coordinates
(x, y, z)
z-score
L IFC
R IFC
L dlPFC
L IFC
L dlPFC
R IFC
R dlPFC
L dlPFC
R dlPFC
47
47
10
47
9
47
9
9
9
(− 48, 19, − 8)
(36, 11, − 11)
(− 44, 47, − 2)
(− 48, 15, − 7)
(− 48, 9, 33)
(40, 11, − 11)
(44, 25, 28)
(− 48, 9, 33)
(44, 25, 28)
4.81
3.94
3.36
3.85
3.72
3.70
3.34
3.21
3.19
367
Table 6
Neural activation for more working memory and less working memory
stimuli
Contrast
Activation Brodmann Coordinates
locus
area (BA) (x, y, z)
With WM−without
L IPC
WM a
Less consistent, with
L IPC
WM−less consistent,
without WM a
z-score
40
(−59, −53, 25) 3.40
40
(−55, −44, 36) 3.45
a
These findings involve contrasts of the final phrase where a temporary
structural ambiguity is resolved minus the initial, unbiased phrase of the
sentence.
a
These findings involve contrasts of the phrase where the structural
ambiguity is resolved minus the initial, unbiased phrase of the sentence.
b
This contrast involves the resolving phrase minus the initial phrase of
each type of sentence.
consistency between the verb and the post-verbal noun. These supplementary results are presented in Appendix D.
We investigated the WM main effect by evaluating cortical
activation patterns that emerged during the terminal phrase
following an additional WM phrase minus the initial phrase of
these sentences. This was compared with activation elicited by the
terminal phrase of a sentence without the extra WM phrase minus
the initial phrase. This contrast, illustrated in Fig. 1D, shows left
IPC activation. Table 6 summarizes the location and statistical
attributes of the peak voxel in this cluster. We also investigated the
interaction between consistency and WM effects. In addition to the
main effect of WM, we found an interaction with “less consistent”
sentences. We observed that IPC showed increased activation for
the WM contrast during presentation of stimuli with less-consistent
verb–sentence structure features. Stimuli with more-consistent
verb–sentence structure features also elicited left IPC activation,
but it did not exceed our statistical threshold.
Discussion
When a temporary structural ambiguity emerges from a conflict
between a verb and its sentence context, executive resources are
recruited to resolve the ambiguity. Our findings indicate that these
resources are supported in large part by dlPFC. Greater dlPFC
activation for the less consistent condition is compatible with the
hypothesis that on-line decision-making uses lexical biases in
sentences to construct an interpretable sentence structure. WM
demands appear to be associated with a different brain region-left
IPC. Taken together, these results indicate that resolving a
temporary structural ambiguity appears to depend on a large-scale
neural network involving multiple components. We address each of
the observed activations below.
Table 5
Percent signal change for more consistent and less consistent stimuli
Contrast
L IFC
L dlPFC
R IFC
R dlPFC
More consistent a
Less consistent a
0.232
0.742
0.194
0.463
0.200
0.406
0.056
0.303
a
These findings refer to the percent signal change in activation between
the final phrase, where a temporary structural ambiguity is resolved, and the
initial, unbiased phrase of the sentence.
Dorsolateral prefrontal cortex
We observed increased activation in dlPFC under a condition of
low consistency between a verb and its sentence context, relative to
high consistency between a verb and its sentence context. The fact
that additional resources are required for a “less consistent” sentence compared to a “more consistent” sentence is less compatible
with the “massive working memory” account of structural ambiguity resolution, where all possible sentence structures are
maintained in working memory during the processing of all types
of sentences. From this perspective, both “more consistent” and
“less consistent” stimuli require equal WM resources since all
possible interpretations of both types must be constructed, and this
will involve equal numbers of representations. Instead, greater
activation for “less consistent” stimuli is more compatible with the
additional planning required for these stimuli compared to “more
consistent” stimuli. dlPFC recruitment for non-linguistic materials
is consistent with this account. For example, activation of this area
is seen during top-down decision-making on Stroop-like tasks
(Braver and Bongiolatti, 2002; MacDonald et al., 2000; Paulus et
al., 2001). While WM-demanding tasks have been shown to
activate dlPFC (Braver et al., 1997; Callicott et al., 1999; Cohen et
al., 1997; Garavan et al., 2000), other work suggests that dlPFC
plays an active role in the strategic manipulation of information
being held in WM (Barch et al., 1997; Prabhakaran et al., 2000;
Rowe and Passingham, 2001; Smith et al., 2001; Sylvester et al.,
2003). A language production task noted dlPFC activation during
grammatically complex sentences involving “Jabberwocky-like”
stimuli in content word positions (Indefrey et al., 2001), but the
feature of grammatical complexity alone may not explain dlPFC
activation since the synthesis of artificial, Jabberwocky material
into complex sentences may require complex planning and decision-making. It is beyond the scope of this report to compare
directly the decision-making resources implicated in sentential and
non-linguistic tasks. Greater activation of dlPFC for “less consistent” stimuli than for “more consistent” stimuli nevertheless
appears to be compatible with previous, non-linguistic work demonstrating the contribution of this area to decision-making and
planning. We cannot, however, exclude the possibility that some of
the difference between conditions may be due in part to factors
related to lexical content beyond those that we did control.
Furthermore, our behavioral results also provide us with evidence compatible with a serial approach supported by dlPFC.
Subjects take longer to read “less consistent” than “more consistent”
stimuli. Moreover, the presence of an additional WM phrase elicits
a significant difference in reading times for “more consistent” sti-
368
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
muli, but not for “less consistent” stimuli. Additional resources are
recruited for processing all “less consistent” stimuli, from our
perspective, thus obscuring the ability to detect behavioral changes
that can be attributed solely to the WM manipulation. However, for
“more consistent” sentences, it is possible to observe increased
demands in the “with WM” condition only, if WM is dissociated
from the decision-making resources involved in verb–sentence
consistency.
Inferior frontal cortex
In the present study, we observed up-regulation of IFC bilaterally under both “more-consistent” and “less-consistent” conditions. This indicates that IFC is involved as a ubiquitous component
supporting sentence processing. Based on observations of aphasics
following stroke (Tramo et al., 1988; Zurif, 1996), neuroimaging
experiments in healthy adults have associated left IFC with
grammatically dependent aspects of sentence processing (BenShachar et al., 2004; Caplan et al., 1998; Caplan et al., 1999; Caplan
et al., 2000; Cooke et al., 2001; Inui et al., 1998; Kang et al., 1999;
Keller et al., 2001; Kuperberg et al., 2003; Kuperberg et al., 2000;
Moro et al., 2001; Newman et al., 2001; Newman et al., 2003; Ni et
al., 2000; Stromswold et al., 1996). Other studies have associated
left IFC with verbal WM (Barch et al., 1997; Braver et al., 2001;
Cohen et al., 1997; Smith and Jonides, 1999). Histological work has
subdivided IFC into two neuroanatomically distinct segments –
dorsal IFC (dIFC) and ventral IFC (vIFC) – based on the
connectivity patterns and cytoarchitectonic characteristics of these
regions (Amunts et al., 1999). These two anatomically distinct subregions may thus perform distinct functions: vIFC appears to
contribute more to the grammatical component of sentence
processing, whereas dIFC is more important for resource-dependent
aspects of sentence processing, such as the WM component (Cooke
et al., 2006; Cooke et al., 2001; Grossman et al., 2002). The
activation peak in our study was located in BA 47 in the ventral part
of left IFC, associating left IFC activation, at least in part, with
syntactic processing of the stimulus sentences. This impression is
consistent with the fact that we did not observe IFC activation
during the WM contrasts within either low-consistency or highconsistency sentences.
We observed right IFC activation during these sentence materials as well. Previous work associated right IFC activation during
sentence processing with the resource demands of a difficult sentence rather than a language-specific process such as grammatical
processing (Just et al., 1996). However, the right-sided locus of this
activation is less likely to be implicated in the WM needed to
maintain multiple grammatical structures in an active state during
processing, since this area has been associated with visual, rather
than verbal, WM (Baddeley, 1992; Jonides et al., 1993; Smith and
Jonides, 1998b; Smith et al., 1996).
Inferior parietal cortex
Left IPC appears to support a component of WM (Awh et al.,
1996; Chein and Fiez, 2001; Jonides et al., 1998; Marshuetz et al.,
2000; Paulesu et al., 1993; Smith and Jonides, 2002). This area may
serve as a phonological buffer, temporarily storing phonological
input information from the verb phrase until the structure of the
sentence can be resolved by the final phrase. In this study, we
expected to see phonological WM associated with IPC activation.
Jonides et al. (1998) obtained activation of BAs 7 and 40 for WM
tasks, and concluded that these parietal regions are part of a cortical
network that mediates short-term storage and retrieval of phonologically coded verbal material. Our results are in agreement with
these, since we found BA 40 to be consistently recruited for conditions with high WM demands. Lesion studies further corroborate
these results: deficits in verbal WM are caused by a lesion in left
posterior parietal cortex and surrounding tissue (Saffran and Marin,
1975; Shallice and Vallar, 1990; Warrington et al., 1971). We may
not have seen left IFC activation during WM demands, as in
previous imaging studies of sentence processing (Cooke et al.,
2006; Cooke et al., 2001), because IFC was subtracted out by its
occurrence in both sentence conditions. Alternately, previous work
showing dIFC activation for WM during sentence processing
(Cooke et al., 2006; Cooke et al., 2001) inserted additional material
between the head noun and the main verb of the sentence. This may
have stressed WM during sentence processing in a manner that
differs from our study, which may explain the absence of an effect
for WM in our behavioral study. In that work, the extra phrase was
placed much earlier in the sentence, thus lengthening the distance
between the gap and the co-indexed noun, which had a direct effect
on the gap-filling component of sentence processing. This is
different from the manipulation done in the sentence materials in
our study, where additional material was inserted after the main
verb, in a manner that does not interrupt or lengthen a co-indexed
gap. For example, temporary maintenance in a phonological buffer
may be particularly useful during on-line decision making to
support recovery from an incorrect structural interpretation. This
may explain greater left IPC activation for “less consistent” stimuli.
There are several interpretations of the observed laterality effect.
Some consider that resources regarding language are lateralized to
the left hemisphere, but some resources used during sentence processing may be material-neutral and bilateral (Just and Carpenter,
1992; Just et al., 1996). We see that IPC activation is lateralized to
the left hemisphere, which is more consistent with this resource
being a material-specific phonological buffer, as suggested in other
work (Jonides et al., 1998).
The area activated for the WM manipulation is left IPC, and this
is associated with the inclusion of the additional phrase: we do not
see IPC activation during the manipulation associated with
decision-making during resolution of the conflict between a verb
and its sentence structure. Thus, manipulating the WM load showed
that additional activation results from this extra phrase independently of the activation associated with solving a temporary
structural ambiguity, and that it is in a different part of the brain.
Furthermore, in another paper in preparation, we find that there is
no accumulation of activation associated with WM during sentence
processing up to the point of disambiguation. These observations
provide us with further evidence consistent with a serial processing
approach. We infer that this disambiguation is related at least in part
to dlPFC.
Neuroanatomical studies have found extensive interconnections
between prefrontal (especially dlPFC) and parietal areas (Mesulam
et al., 1977; Pandya and Seltzer, 1982; Petrides and Pandya, 1984).
Furthermore, these two cortical regions project to common cortical
and subcortical areas (Selemon and Goldman-Rakic, 1988), and
primates show the co-activation of these regions during WM tasks
(Friedman and Goldman-Rakic, 1994). It is neuroanatomically
plausible to suggest that there is a systematic coactivation of these
regions during processing of sentences with a temporary structural
ambiguity and high working memory load, as we observed in our
study.
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Appendix A (continued)
Conclusion
No. V
The findings of the present study are consistent with a structure
building process during sentence comprehension that involves at
least serial, on-line decision-making. This process is supported by
dlPFC. Moreover, WM resources that contribute to sentence
comprehension are supported by IPC. These resources appear to
play a role in a large-scale neural network that supports language
processing. Observations such as these are consistent with a twocomponent model of sentence processing: the core peri-Sylvian
language processing regions that include IFC, and a set of executive
resources that involves at least dlPFC and IPC. These resources are
activated as needed, when the core regions require additional
support to process a given stimulus.
Acknowledgments
This work was supported in part by NIH (NS35867, AG17586,
NS44266 and AG15116) and the Dana Foundation. Susana
Novais-Santos is also supported by the Portuguese Foundation
for Science and Technology (SFRH/BD/10205/2002).
Appendix A. Stimulus sentences
The table below contains all 240 stimuli used in the study, and
indicates the types of verb (V), noun (N) and sentence (S), the
absence (“−”) or presence (“+”) of an additional WM phrase, as well
as the level of consistency (C) [more (“M”) or less (“L”)], for each
stimulus
No. V
WM C
Sentence
1
DO DO SC
−
L
2
DO DO SC
+
L
3
DO DO DO −
M
4
DO DO DO +
M
5
DO SC
SC
−
L
6
DO SC
SC
+
L
7
DO SC
DO −
M
8
DO SC
DO +
M
9
DO DO SC
−
L
10
DO DO SC
+
L
11
DO DO DO −
M
12
DO DO DO +
M
13
DO SC
SC
−
L
14
DO SC
SC
+
L
The worried friar asserted the belief
would be justified.
The concerned priest asserted the belief
in stone-idol worship was ungrounded.
The diligent disciple asserted the belief
readily.
The old nun asserted the belief in various
religious cults authoritatively.
The passionate artist asserted the truth
would be difficult.
The city-sweeper asserted the truth about
minimum wage payments was shocking.
The loud newsreader asserted the truth
cheerfully.
The sleepy student asserted the truth
about cheating on tests merrily.
The CIA director confirmed the rumor
should be stopped now.
The town gossip confirmed the rumor
about the newly-weds was false.
The friendly neighbor confirmed the
rumor in an instant.
The talkative servant confirmed the
rumor about the prime minister slowly.
The financial assistant confirmed the
money should be managed better.
The newspaper agency confirmed the
money from the local bank had been
stolen.
The new accountant confirmed the
money immediately.
15
N
DO SC
369
S
DO −
M
N
S
WM C
16
DO SC
DO +
17
DO DO SC
−
18
DO DO SC
+
19
DO DO DO −
20
DO DO DO +
21
DO SC
SC
−
22
DO SC
SC
+
23
DO SC
DO −
24
DO SC
DO +
25
DO DO SC
−
26
DO DO SC
+
27
DO DO DO −
28
DO DO DO +
29
DO SC
SC
−
30
DO SC
SC
+
31
DO SC
DO −
32
DO SC
DO +
33
DO DO SC
−
34
DO DO SC
+
35
DO DO DO −
36
DO DO DO +
37
DO SC
SC
−
38
DO SC
SC
+
39
DO SC
DO −
40
DO SC
DO +
41
DO DO SC
−
42
DO DO SC
+
43
DO DO DO −
Sentence
M The computing program confirmed the
money from New York instantaneously.
L The angry father emphasized the
shortcomings were numerous.
L The fire fighter emphasized the
shortcomings of the faulty hoses were
increasing.
M The impoverished archaeologist
emphasized the shortcomings forcefully.
M The experienced judge emphasized the
shortcomings of the legal system with
concern.
L The talented photographer emphasized
the schools were ignoring photography.
L The irate parents emphasized the schools
across the entire nation had uninterested
teachers.
M The finance minister emphasized the
schools when addressing the public.
M The teaching inspectors emphasized the
schools with strong sports teams in their
annual report.
L The hitch-hiker heard the story was not
true.
L The primary suspect heard the story
given by his friend was a lie.
M The busy psychiatrist heard the story
briefly.
M The doting grandfather heard the story
with all its exaggerations unhappily.
L The naughty boy heard the neighbors
were evil.
L The nosy butler heard the neighbors on
the first floor were nice people.
M The bus-conductor heard the neighbors
daily.
M The cleaning-woman heard the neighbors
from the adjoining house each night.
L The maintenance people insured the
house would not collapse again.
L The young architect insured the house
with the expensive interior was sold.
M The new owners insured the house
quickly.
M The old proprietor insured the house in
upstate New York as soon as possible.
L The honeymoon couple insured the river
would never flood their property.
L The aged gardener insured the river with
the varying current would not wash
away his daisies.
M The eccentric landlord insured the river
in court.
M The wicked baron insured the river on
his huge estate at once.
L The stubborn technician maintained the
machinery was state-of-the-art.
L The displeased client maintained the
machinery with the fancy gadgets was
obsolete.
M The confident engineer maintained the
machinery diligently.
(continued on next page)
370
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Appendix A (continued)
Appendix A (continued)
No. V
N
S
WM C
44
DO DO DO +
45
DO SC
SC
−
46
DO SC
SC
+
47
DO SC
DO −
48
DO SC
DO +
49
DO DO SC
−
50
DO DO SC
+
51
DO DO DO −
52
DO DO DO +
53
DO SC
SC
−
54
DO SC
SC
+
55
DO SC
DO −
56
DO SC
DO +
57
DO DO SC
−
58
DO DO SC
+
59
DO DO DO −
60
DO DO DO +
61
DO SC
SC
−
62
DO SC
SC
+
63
DO SC
DO −
64
DO SC
DO +
65
DO DO SC
−
66
DO DO SC
+
67
DO DO DO −
68
DO DO DO +
69
DO SC
SC
−
70
DO SC
SC
+
Sentence
M The partisan architect maintained the
machinery without the spare parts at the
cost of the others.
L The arrogant candidate maintained the
debate was easy to win.
L The persistent opponent maintained the
debate over the ambiguous issue would
continue.
M The disagreeing students maintained the
debate stubbornly.
M The quarreling parents maintained the
debate over their children's futures
unendingly.
L The journal editor printed the article was
slanderous.
L The famous actress printed the article on
her scandalous affair was untrue.
M The pretty popstar printed the article
happily.
M The ecstatic editor printed the article on
Superman's daring adventures gleefully.
L The bitter divorcee printed the statement
had been irresponsible.
L The annoyed author printed the
statement of the callous media was
ruining sales of his book.
M The temperamental publisher printed the
statement hastily.
M The enthusiastic lawyer printed the
statement of his client's complaint
painstakingly.
L The art critic wrote the interview was
tedious.
L The cynical newsperson wrote the
interview with the popular celebrity was
a huge success.
M The pensive screenwriter wrote the
interview thoughtfully.
M The acclaimed writer wrote the
interview with the presidential candidate
beautifully.
L The art collector wrote the paper was a
clever forgery.
L The nutty thief wrote the paper with the
crumpled edges was easy to burn.
M The versatile poet wrote the paper
brilliantly.
M The ugly madman wrote the paper on
popular classical music proudly.
L The surgical nurses protested the policy
was not fair to patients.
L The enraged mob protested the policy on
public welfare issues was being
overlooked.
M The rebelling youngsters protested the
policy fearlessly.
M The ruthless instigators protested the
policy on universal adult franchise
without hesitating.
L The hospital authorities protested the
actions were not fair.
L The upset families protested the actions
of the renowned hospital were illegal.
No. V
N
S
WM C
71
DO SC
DO −
72
DO SC
DO +
73
DO DO SC
−
74
DO DO SC
+
75
DO DO DO −
76
DO DO DO +
77
DO SC
SC
−
78
DO SC
SC
+
79
DO SC
DO −
80
DO SC
DO +
81
EQ
DO SC
−
82
EQ
DO SC
+
83
EQ
DO DO −
84
EQ
DO DO +
85
EQ
SC
SC
−
86
EQ
SC
SC
+
87
EQ
SC
DO −
88
EQ
SC
DO +
89
EQ
DO SC
−
90
EQ
DO SC
+
91
EQ
DO DO −
92
EQ
DO DO +
93
EQ
SC
SC
−
94
EQ
SC
SC
+
95
EQ
SC
DO −
96
EQ
SC
DO +
Sentence
M The underpaid surgeons protested the
actions vigorously.
M The overworked staff protested the
actions of the new doctor for a week.
L The trained referees warned the
spectators were rowdy.
L The security personnel warned the
spectators at the state championships
were agitated.
M The performing artist warned the
spectators before starting the show.
M The weather forecasters warned the
spectators of the baseball game in
advance.
L The news commentators warned the
nation would be vulnerable.
L The impartial secretary warned the
nation in such bad times would face
financial problems.
M The ancient philosopher warned the
nation a thousand years ago.
M The zealous patriot warned the nation
with the uncaring aristocracy well in
advance.
M The overjoyed fiancée announced the
wedding was a big event.
M The wedding planners announced the
wedding with all its trimmings was
costly.
M The eloped couple announced the
wedding the next day.
M The inquisitive reporter announced the
wedding of Mary and John without
permission.
M The disappointed client announced the
flowers were wilted.
M The blushing schoolgirl announced the
flowers with the lovely scent were
beautiful.
M The friendly florist announced the
flowers with pride.
M The charming housemaid announced the
flowers in the pretty basket in a booming
voice.
M The new mayor declared the holiday was
a festive occasion.
M The stern grandmother declared the
holiday of over a week was unnecessary.
M The respected senator declared the
holiday happily.
M The exhausted mother declared the
holiday before the final exams without
regret.
M The road minister declared the winner
was absent.
M The exasperated driver declared the
winner of the new limousine was
ungrateful.
M The amused pedestrians declared the
winner unanimously.
M The naval officer declared the winner of
the Grand Prix on the day of the event.
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Appendix A (continued)
Appendix A (continued)
No. V
N
S
97
EQ
DO SC
−
98
EQ
DO SC
+
99
EQ
DO DO −
100 EQ
DO DO +
101 EQ
SC
SC
−
102 EQ
SC
SC
+
103 EQ
SC
DO −
104 EQ
SC
DO +
WM C
105 EQ
DO SC
−
106 EQ
DO SC
+
107 EQ
DO DO −
108 EQ
DO DO +
109 EQ
SC
SC
−
110 EQ
SC
SC
+
111 EQ
SC
DO −
112 EQ
SC
DO +
113 EQ
DO SC
−
114 EQ
DO SC
+
115 EQ
DO DO −
116 EQ
DO DO +
117 EQ
SC
SC
−
118 EQ
SC
SC
+
119 EQ
SC
DO −
120 EQ
SC
DO +
121 EQ
DO SC
−
122 EQ
DO SC
+
123 EQ
DO DO −
124 EQ
DO DO +
371
Sentence
M The crooked politician denied the
accusation was true.
M The sales clerk denied the accusation of
grand jewelry theft was valid.
M The flower girl denied the accusation
flatly.
M The guilty servant denied the accusation
of stealing precious goods strongly.
M The defense attorney denied the election
was rigged.
M The obstinate judges denied the election
of the twenty contestants was
pre-determined.
M The previous president denied the
election emphatically.
M The insecure monarch denied the
election of a democratic council
immediately.
M The gifted ice-skater doubted the judges
were fair.
M The nervous defendant doubted the
judges of the Supreme Court were
unbiased.
M The skeptical superintendent doubted
the judges from the very beginning.
M The shrewd president doubted the judges
of the state government highly.
M The famous singer doubted the storm
would stop the show.
M The weather channel doubted the storm
with its torrential downpours would
cease.
M The arrogant pilot doubted the storm
after looking at the sky.
M The first mate doubted the storm of
supposedly great magnitude on seeing
the sunshine.
M The petrified cousin feared the tantrums
would intensify.
M The young babysitter feared the
tantrums with kicking and squealing
would upset the newborn.
M The gentle aunt feared the tantrums
greatly.
M The timid headmistress feared the
tantrums of my best friend intensely.
M The anxious bride feared the dress was
torn.
M The illustrious tailor feared the dress
with the bright sequins was ripped.
M The schizophrenic girl feared the dress
with all her heart.
M The prominent filmstar feared the dress
with the low neckline very much.
M The well-known spokesperson
guaranteed the product was new.
M The persistent salesman guaranteed the
product at the new store was excellent.
M The talented designer guaranteed the
product personally.
M The insurance company guaranteed the
product with the latest modifications
completely.
No. V
N
S
WM C
125 EQ
SC
SC
−
126 EQ
SC
SC
+
127 EQ
SC
DO −
128 EQ
SC
DO +
129 EQ
DO SC
−
130 EQ
DO SC
+
131 EQ
DO DO −
132 EQ
DO DO +
133 EQ
SC
SC
−
134 EQ
SC
SC
+
135 EQ
SC
DO −
136 EQ
SC
DO +
137 EQ
DO SC
-
138 EQ
DO SC
+
139 EQ
DO DO −
140 EQ
DO DO +
141 EQ
SC
SC
−
142 EQ
SC
SC
+
143 EQ
SC
DO −
144 EQ
SC
DO +
145 EQ
DO SC
−
146 EQ
DO SC
+
147 EQ
DO DO −
148 EQ
DO DO +
149 EQ
SC
SC
−
150 EQ
SC
SC
+
151 EQ
SC
DO −
152 EQ
SC
DO +
Sentence
M The anxious shopkeeper guaranteed the
job would be fun.
M The chic restaurant guaranteed the job of
cleaning the dishes was well-paying.
M The well-to-do artiste guaranteed the job
herself.
M The dishonest trader guaranteed the job
at the Stock Exchange to his client.
M The desk clerk guessed the name was
scribbled.
M The police sergeant guessed the name
with the five syllables was fake.
M The fortune-teller guessed the name in a
jiffy.
M The bright receptionist guessed the name
of my best friend in an instant.
M The intelligent boy guessed the solution
was simple.
M The engaged couple guessed the
solution to all their problems was to get
married.
M The child genius guessed the solution
easily.
M The eccentric mathematician guessed
the solution to the geometry problem at
once.
M The famous novelist knew the material
was unusual.
M The education board knew the material
on advanced quantum physics was
complicated.
M The industrious child knew the material
by heart.
M The tense interviewee knew the material
from the prescribed textbook by heart.
M The practiced orator knew the pause was
a mistake.
M The fumbling actor knew the pause of
three seconds was noticed.
M The talented musician knew the pause
immediately.
M The devoted composer knew the pause
of two full beats well.
M The publicity agent predicted the
problem was troublesome.
M The worried statistician predicted the
problem of too many overheads could be
devastating.
M The international advisors predicted the
problem in advance.
M The skeptical in-laws predicted the
problem in the hasty marriage the first
day itself.
M The fashion designer predicted the
clothes would sell.
M The fussy supermodel predicted the
clothes on the summer line would be
unpopular.
M The fashion guru predicted the clothes
unsuccessfully.
M The press reporter predicted the clothes
at the fashion festival accurately.
(continued on next page)
372
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Appendix A (continued)
Appendix A (continued)
No. V
N
S
WM C
153 EQ
DO SC
−
154 EQ
DO SC
+
155 EQ
DO DO −
156 EQ
DO DO +
157 EQ
SC
SC
−
158 EQ
SC
SC
+
159 EQ
SC
DO −
160 EQ
SC
DO +
161 SC
DO SC
−
162 SC
DO SC
+
163 SC
DO DO −
164 SC
DO DO +
165 SC
SC
SC
−
166 SC
SC
SC
+
167 SC
SC
DO −
168 SC
SC
DO +
169 SC
DO SC
−
170 SC
DO SC
+
171 SC
DO DO −
172 SC
DO DO +
173 SC
SC
SC
−
174 SC
SC
SC
+
175 SC
SC
DO −
176 SC
SC
DO +
177 SC
DO SC
−
178 SC
DO SC
+
Sentence
M The skilled negotiator sensed the
conflict was ongoing.
M The marriage counselor sensed the
conflict on such important issues was
unsettled.
M The third person sensed the conflict
immediately.
M The shrewd solicitor sensed the conflict
in his clients' interests immediately.
M The powerful government sensed the
tension would be resolved.
M The soldier's family sensed the tension
between the warring nations was
heightening.
M The palm reader sensed the tension
intuitively.
M The perceptive teenager sensed the
tension between her closest friends at
once.
M The sympathetic teacher admitted the
schoolgirl was careless.
M The caring aunt admitted the schoolgirl
with the two pigtails was actually very
naughty.
L The selective college admitted the
schoolgirl in the end.
L The admissions committee admitted the
schoolgirl with the excellent grades right
away.
M The inconsiderate pilot admitted the
airplane was not on time.
M The flight attendant admitted the
airplane with the extra facilities was not
as fast.
L The control tower admitted the airplane
at once.
L The hangar operator admitted the
airplane with the damaged propeller
unquestioningly.
M The office manager indicated the trouble
was not insurmountable.
M The police chief indicated the trouble at
the main headquarters was serious.
L The burnt houses indicated the trouble
for all to see.
L The crumbling economy indicated the
trouble of the unfortunate citizens to the
whole world.
M The supercilious lieutenant indicated the
remark was impertinent.
M The stiff colonel indicated the remark
about the armed forces was
inappropriate.
L The college professor indicated the
remark with a nod.
L The excelling student indicated the
remark on his report card with immense
pride.
M The weary traveler claimed the luggage
was stolen.
M The airport guards claimed the luggage
without the orange tag was unidentified.
No. V
N
S
179 SC
DO DO −
L
180 SC
DO DO +
L
181 SC
SC
SC
−
M
182 SC
SC
SC
+
M
183 SC
SC
DO −
L
184 SC
SC
DO +
L
185 SC
DO SC
−
M
186 SC
DO SC
+
M
187 SC
DO DO −
L
188 SC
DO DO +
L
189 SC
SC
SC
−
M
190 SC
SC
SC
+
M
191 SC
SC
DO −
L
192 SC
SC
DO +
L
193 SC
DO SC
−
M
194 SC
DO SC
+
M
195 SC
DO DO −
L
196 SC
DO DO +
L
197 SC
SC
SC
−
M
198 SC
SC
SC
+
M
199 SC
SC
DO −
L
200 SC
SC
DO +
L
201 SC
DO SC
−
M
202 SC
DO SC
+
M
203 SC
DO DO −
L
204 SC
DO DO +
L
205 SC
SC
−
M
SC
WM C
Sentence
The tired passenger claimed the luggage
eagerly.
The brazen thief claimed the luggage
with the expensive jewels without
hesitation.
The handicapped gentleman claimed the
attendant was surly.
The eight-year-old claimed the attendant
in the blue dress was mean to her.
The infatuated emperor claimed the
attendant for his own.
The turbulent sea claimed the attendant
from the suburban area in a plane crash.
The account executive concluded the
speech was a disaster.
The judicial council concluded the
speech on critical legal issues was
unresearched.
The university head concluded the
speech hastily.
The overworked social worker
concluded the speech on basic civil
rights extremely quickly.
The tax inspectors concluded the issue
was unresolvable.
The bankrupt client concluded the issue
with the bank manager had worked
against him.
The docile wife concluded the issue
quickly.
The bankers' meeting concluded the
issue with the overseas branch at once.
The cab driver assumed the blame
belonged to the pedestrian.
The irresponsible architect assumed the
blame for the building's collapse didn't
lie with him.
The responsible grandson assumed the
blame squarely.
The protective brother assumed the
blame for the car accident in place of his
sister.
The Hollywood actress assumed the
appearance was temporary.
The harrowed uncle assumed the
appearance of his wild nephew would
soon improve.
The heavyweight champion assumed the
appearance reluctantly.
The clever mime assumed the
appearance of an old lady very
convincingly.
The astute jeweler figured the prices
were steep.
The poor farmer figured the prices of
large Idaho potatoes would fall lower.
The confirmed shopper figured the
prices without looking at the price tags.
The miserly housewife figured the prices
of the latest clothes before asking the
assistant.
The dedicated anthropologist figured the
answer was right there.
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
Appendix A (continued)
Appendix A (continued)
No. V
N
S
WM C
206 SC
SC
SC
+
207 SC
SC
DO −
208 SC
SC
DO +
209 SC
DO SC
−
210 SC
DO SC
+
211 SC
DO DO −
212 SC
DO DO +
213 SC
SC
SC
−
214 SC
SC
SC
+
215 SC
SC
DO −
216 SC
SC
DO +
217 SC
DO SC
−
218 SC
DO SC
+
219 SC
DO DO −
220 SC
DO DO +
221 SC
SC
SC
−
222 SC
SC
SC
+
223 SC
SC
DO −
224 SC
SC
DO +
225 SC
DO SC
−
226 SC
DO SC
+
227 SC
DO DO −
228 SC
DO DO +
229 SC
SC
SC
−
230 SC
SC
SC
+
231 SC
SC
DO −
232 SC
SC
DO +
373
Sentence
M The ambitious salesgirl figured the
answer to all her problems was to finish
her education.
L The eighth grader figured the answer
eventually.
L The eager archaeologist figured the
answer to the temple inscriptions
without delay.
M The union leader implied the raise was
needed.
M The older employees implied the raise of
a hundred dollars was welcome.
L The caring boss implied the raise
through indirect comments.
L The new administration implied the raise
in crude oil prices very subtly.
M The fearless rebels implied the weather
was responsible.
M The agricultural community implied the
weather with its unreliable nature was
dangerous.
L The lazy fisherman implied the weather
shamelessly.
L The highway patrol implied the weather
of the past few days conveniently.
M The young craftsman realized the
mistake was grave.
M The college professor realized the
mistake on the midterm exam was
genuine.
L The foolish goldsmith realized the
mistake after adding the final touches to
his work.
L The federal agent realized the mistake of
blaming the system at that moment.
M The dispassionate arbitrator realized the
situation was hopeless.
M The observant handyman realized the
situation with the chipped tools was
worsening.
L The querulous wife realized the situation
too late.
L The foster-parents realized the situation
between their two children too late.
M The conservative scriptwriter suggested
the scene was explicit.
M The actress's mother suggested the
scene with the controversial comments
was unnecessary.
L The celebrated author suggested the
scene eagerly.
L The director's cook suggested the scene
with the kitchen backdrop hopefully.
M The royal household suggested the
mansion was unsuitable.
M The overworked sweeper suggested the
mansion with the four floors was
unmanageable.
L The married couple suggested the
mansion excitedly.
L The hopeful house-agent suggested the
mansion with the antique furniture
eagerly.
No. V
N
S
WM C
233 SC
DO SC
−
234 SC
DO SC
+
235 SC
DO DO −
236 SC
DO DO +
237 SC
SC
SC
−
238 SC
SC
SC
+
239 SC
SC
DO −
240 SC
SC
DO +
Sentence
M The factory owner suspected the
workers were going on strike.
M The silent attorney suspected the
workers from the neighboring suburbs
were objecting.
L The police chief suspected the workers
instinctively.
L The deputy-in-charge suspected the
workers at the crime scene without
reason.
M The prodigal son suspected the cash was
thinning out.
M The jealous cousin suspected the cash in
his brother's care was plentiful.
L The demented inmate suspected the cash
nervously.
L The security panel suspected the cash in
the white envelope on sight.
Appendix B. Stimulus verbs
The table below contains all verbs used in the study, along with
their DO-preference and SC-preference (in a 0 to 1 scale).
Verb bias
Verb
DO-preference
SC-preference
DO
Asserted
Confirmed
Emphasized
Heard
Insured
Maintained
Printed
Protested
Warned
Wrote
Admitted
Assumed
Claimed
Concluded
Figured
Implied
Indicated
Realized
Suggested
Suspected
Announced
Declared
Denied
Doubted
Feared
Guaranteed
Guessed
Knew
Predicted
Sensed
0.64
0.71
0.75
0.74
0.84
0.74
0.78
0.58
0.74
0.87
0.09
0.09
0.06
0.14
0.08
0.06
0.21
0.14
0.18
0.29
0.49
0.44
0.33
0.42
0.32
0.46
0.39
0.31
0.45
0.53
0.31
0.25
0.19
0.16
0.13
0.23
0.01
0.11
0.11
0.00
0.60
0.89
0.69
0.80
0.46
0.90
0.70
0.77
0.61
0.68
0.48
0.52
0.27
0.56
0.48
0.50
0.25
0.46
0.51
0.45
SC
EQ
Appendix C. Stimulus nouns
The tables below contain all nouns used in the study, along with
the verb that precedes them, as well as the post-verbal noun
374
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
plausibility ratings. A high score (maximum: 7) means that the
post-verbal noun is a plausible direct object (DO) of its
predecessing verb; a low score indicates an SC-biased noun.
Nouns following DO-bias verbs
Verb
Noun
Rating
Feared
Verb
Noun
Rating
Guessed
Asserted
Belief
Truth
Rumor
Money
Shortcomings
Schools
Story
Neighbors
House
River
Machinery
Debate
Article
Statement
Interview
Paper
Policy
Actions
Spectators
Nation
5.06
2.42
6.89
4.24
6.38
3.71
6.53
3.97
7.00
2.47
6.35
3.00
6.75
3.18
6.11
3.59
6.58
2.86
6.51
3.74
Knew
Tantrums
Dress
Product
Job
Name
Solution
Material
Pause
Problem
Clothes
Conflict
Tension
6.47
3.65
6.79
4.17
6.26
3.73
6.79
2.54
6.53
2.74
6.74
4.22
Confirmed
Emphasized
Heard
Insured
Maintained
Printed
Wrote
Protested
Warned
Nouns following SC-bias verbs
Verb
Noun
Rating
Admitted
Schoolgirl
Airplane
Blame
Appearance
Luggage
Attendant
Speech
Issue
Prices
Answer
Raise
Weather
Trouble
Remark
Mistake
Situation
Scene
Mansion
Workers
Cash
6.11
2.12
6.35
2.67
6.89
2.29
6.39
3.72
6.42
3.58
4.95
2.29
6.07
3.46
6.41
2.16
5.93
2.31
6.58
3.29
Assumed
Claimed
Concluded
Figured
Implied
Indicated
Realized
Suggested
Suspected
Nouns following EQ-bias verbs
Verb
Noun
Rating
Announced
Wedding
Flowers
Holiday
Winner
Accusation
Election
Judges
Storm
6.76
2.32
6.08
3.46
6.83
3.49
6.47
3.59
Declared
Denied
Doubted
Guaranteed
Predicted
Sensed
Appendix D. Verb and noun analyses
D.1. Verb type
We investigated effects associated with manipulating the type
of verb. These contrasts examined activations during the final
phrase minus the initial, unbiased phrase. Because of the number of
items, there was insufficient power to analyze each of these types
of verbs in each sentence context. Activation patterns for these
contrasts are illustrated in Fig. 2, and the location and statistical
attributes of the peak voxel in each cluster are summarized in Table
A1. For stimuli with a DO-biased verb, we observed bilateral IFC
and right dlPFC activation (Fig. 2A). For stimuli with an SC verb,
we observed activation in left IFC and bilateral dlPFC (Fig. 2B).
Bilateral IFC activation remains after direct subtraction of “SC
verb” stimuli from “DO verb” stimuli (Fig. 2C). Left dlPFC
activation remains after direct subtraction of “DO verb” stimuli
from “SC verb” stimuli (Fig. 2D).
Different activation patterns emerge for DO verbs and SC
verbs. The former type expects to be followed by a noun that fills
the grammatical role of direct object and the thematic role of theme
(or object) of the action described by the verb. This is the canonical
form of a sentence in English, which is an SVO (subject-verbobject) language. This may be consistent with the possibility that,
in comparison to SC verbs, DO verbs should elicit higher
activation in the core language region-Broca's area. Other studies
have shown activation of the right hemisphere homologue of
Broca's area during sentence processing (Carpenter et al., 1999;
Embick et al., 2000; Just et al., 1996). One proposal relates this to
greater grammatical difficulty (Just et al., 1996), although it is not
clear that DO verbs are more demanding than SC verbs. SC verbs,
on the other hand, usually entail, or presuppose, a more complex
predicate-argument structure (Shapiro et al., 1987, 1989), having
more processing nodes involved in their representation and thus a
more complex binding (Chomsky, 1981). We observed increased
left dlPFC activation elicited by this type of verbs, when compared
to DO verbs. This finding may suggest that a strategy is being
devised to interpret the sentence with a more complex syntactical
framework in mind.
In our behavioral analysis, we observed no difference in verb
reading times during verb presentation per se, which was expected,
since verb types did not differ significantly in length. However, we
measured a significant reaction time difference during sentence
disambiguation when taking into consideration the sentential
context in which each verb type is embedded, and thus the
consistency level of the stimulus (i.e. “more consistent” or “less
consistent”), as discussed in the main text.
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
375
Fig. 2. Distribution of activation during the last phrase (relative to the first phrase)
for stimuli with a DO verb (A) and with an SC verb (B). The bottom two panels
depict the contrasts of these two conditions: “DO verb” stimuli minus “SC verb”
stimuli (C) and “SC verb” stimuli minus “DO verb” stimuli (D).
D.2. Verb–noun consistency
We also investigated the effect of manipulating the consistency
between the verb and the post-verbal noun. Behavioral analyses
show that subjects take longer to process sentences in which the
noun is less consistent with its preceding verb (mean (± SD) =
729.19 (± 273.39) ms) than to process stimuli in which the postverbal noun is more consistent with the verb (mean (± SD) =
665.15 (± 247.95) m). Activation patterns for these stimuli are
illustrated in Fig. 3, and the location and statistical attributes of the
peak voxel in each cluster are summarized in Table A2. For stimuli
Table A1
Neural activation patterns for “DO verb” and “SC verb” stimuli
Contrast
Activation
locus
Brodmann
area (BA)
Coordinates
(x, y, z)
z-score
DO verb a
L IFC
R IFC
R dlPFC
L dlPFC
R dlPFC
L IFC
L IFC
R IFC
L dlPFC
47
47
9
9
6
47
47
47
8
(−40, 19, − 11)
(40, 11, − 14)
(44, 25, 28)
(−48, 13, 32)
(24, − 5, 59)
(−40, 19, − 11)
(−44, 19, − 8)
(44, 23, − 1)
(−32, 18, 43)
4.64
4.46
4.17
3.77
3.42
4.17
3.34
3.18
3.13
SC verb a
DO verb–SC
verb b
SC verb–DO
verb b
a
These findings involve contrasts of the phrase where the structural
ambiguity is resolved minus the initial, unbiased phrase of the sentence.
b
This contrast involves the resolving phrase minus the initial phrase of
each type of sentence.
Fig. 3. Distribution of activation during the last phrase (relative to the first
phrase) for stimuli in which the noun is “more consistent” with the preceding
verb (A) and in which the noun is “less consistent” with the verb (B). Panel C
depicts the contrast of these two conditions (“less consistent verb–noun”
minus “more consistent verb–noun”).
in which the noun is more consistent with its preceding verb, we
observed bilateral middle temporal cortex (MTC) and left IFC
activation (Fig. 3A). For stimuli in which the noun is less
Table A2
Neural activation patterns for “more consistent verb–noun” and “less
consistent verb–noun” stimuli
Contrast
Activation
locus
Brodmann
area (BA)
Coordinate
(x, y, z)
z-score
More consistent
VN a
R MTC
L MTC
L IFC
L dlPFC
L IFC
L STC
L PCC
21
21
47
9
45
39
29
(55, − 47, 2)
(− 67, − 28, − 8)
(− 32, 19, −4)
(− 51, 17, 29)
(− 51, 24, 21)
(− 59, − 61, 21)
(− 16, − 49, 21)
3.85
3.43
3.18
3.09
3.05
3.16
3.11
Less consistent
VN a
Less consistent
VN–more
consistent VN b
a
These findings involve contrasts of the phrase where the structural
ambiguity is resolved minus the initial, unbiased phrase of the sentence.
b
This contrast involves the resolving phrase minus the initial phrase of
each type of sentence.
376
S. Novais-Santos et al. / NeuroImage 37 (2007) 361–378
consistent with the verb, we observed activation in left dlPFC and
in left IFC, although the latter was just below the significant
threshold (Fig. 3B).
Distinct activation patterns emerge for conditions in which the
nominal phrase is more consistent or less consistent with its
preceding verbal phrase. The former condition elicits higher
activation in language regions-Broca's area and Wernicke's area
(as well as its right homologue). One possibility is that when the
noun fills the grammatical role it was expected to play, core
language regions are more strongly activated. It is important to
mention that both conditions recruit left IFC, as expected in a
sentence processing task. In the “less consistent verb–noun”
condition, however, left IFC activity is just below the significant
threshold (p b 0.0012; z-score = 3.05) and is thus not depicted in the
figure.
On the other hand, when the noun is less consistent with the
preceding verb, the thematic expectations are not met, and thus the
reader has to re-construct the representation of the sentence. This
additional processing should be translated into recruitment of
additional executive resources. We observed increased left dlPFC
activation for these stimuli, possibly reflecting the planning needed
to resolve the “less consistent verb–noun” condition.
We subsequently compared these two conditions directly, by
performing direct subtractions of these contrasts. No areas showed
higher activation levels for the direct subtraction “more consistent
verb–noun” minus “less consistent verb–noun” stimuli. Direct
subtraction of “less consistent verb–noun” minus “more consistent
verb–noun” stimuli elicited activation in left superior temporal
cortex (STC) and left posterior cingulate cortex (PCC). Activation
patterns for these stimuli are illustrated in Fig. 3, and the location
and statistical attributes of the peak voxel in each cluster are
summarized in Table A2.
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