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PSY 369: Psycholinguistics
Language and the brain
Localization of function

Josef Gall’s
phrenology


Mental functions
(e.g., intellect,
morals, etc.) are
supported by specific
regions of the brain
You can feel the
skull to assess
people’s mental
abilities
Localization of function

Modern
Neuropsychology

Psychological
functions are localized
in particular regions of
the brain
Location of ‘Language Organ’

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Language facilities seem to be primarily located in
the left hemisphere (97% of right handers, 81%
lefties)
Much of the evidence for the localization of
language facilities comes from patients with
language disorders
Other evidence from:

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“Split-brain” patients
Dichotic listening exps (words presented to the right ear
better)
Modern Imaging techniques
The “language organ”
Language Disorders


Egyptians reported
speech loss after blow
to head 3000 years ago
Broca (1861) finds
damage to left inferior
frontal region (Broca’s
area) of a language
impaired patient, in
postmortem analysis
Lateralization of the Brain


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Human body is asymmetrical: heart, liver, use of
limbs, etc.
Functions of the brain become lateralized
Each hemisphere specialized for particular ways of
working
Lateralization of functions

Left-hemisphere:

Sequential analysis



Analytical
Problem solving

Right-hemisphere:

Simultaneous analysis

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Visual-Spatial skills

Language

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Cognitive maps
Personal space
Facial recognition
Drawing
Emotional functions


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Synthetic
Recognizing emotions
Expressing emotions
Music
Language Disorders

Lateralization In language disorders


90-95% of cases, damage is to the left
hemisphere
5-10% of cases, to the right hemisphere
Language Disorders

Wada test is used
to determine the
hemispheric
dominance


Sodium amydal is
injected to the
carotid artery
First to the left and
then to the right
Split-brain



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Epileptic activity spread from one hemisphere to
the other thru corpus callosum
Since 1930, such epileptic treated by severing
the interhemispheric pathways
At first no detectible changes (e.g. IQ)
Animal research revealed deficits:



Cat with both corpus callosum and optic chiasm
severed
Left-hemisphere could be trained for symbol:reward
Right-hemisphere could be trained for inverted
symbol:reward
Normal Cortical Connections
Language
Dominant Side
Broca’s
Area
Motor
Cortex
Callosal
Connections
Motor
Cortex
What changes
if the corpus
callosum is
damaged?
The Split Brain Studies
Language
Dominant Side
Broca’s
Area
Motor
Cortex
Motor
Cortex
Can identify the cat
The Split Brain Studies
Language
Dominant Side
Broca’s
Area
Motor
Cortex
Motor
Cortex
The left hand can
point to it, but you
can’t describe it!
Left vs. Right Brain

Pre and post operation studies showed that:

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Selective stimulation of the right and left hemisphere was
possible by stimulating different parts of the body (e.g.
right/left hand):
 Thus can test the capabilities of each hemisphere
Left hemisphere could read and verbally communicate
Right hemisphere had small linguistic capacity: recognize
single words
Vocabulary and grammar capabilities of right is far less than
left
Only the processes taking place in the left hemisphere could
be described verbally
Other studies

Right ear advantage in dicothic listening:


Due to interhemispheric crossing
Words in left-hemisphere, Music in right

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Supported by damage and imaging studies
But perfect-pitch is still on the left
Language Disorders

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Aphasia – more to follow
Other disorders include

Paraphasia:
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Neologism:

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Talking with considerable effort
Agraphia:
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Paraphasia with a completely novel word
Nonfluent speech:

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Substitution of a word by a sound, an incorrect word, or an unintended
word
Impairment in writing
Alexia:

Disturbances in reading
Clinical Aphasia Classifications

Broca’s (cortical motor) - slow, effortful halting speech,
lacking grammatical words


Me … build-ing … chairs,
no, no cab-in-nets. One,
saw … then, cutting wood
… working …
Cookie jar … fall over …
chair … water … empty …
ov … ov … (Examiner:
“overflow”] Yeah.
Clinical Aphasia Classifications

Broca’s (cortical motor) - slow, effortful halting speech,
lacking grammatical words
• Most also lost the ability to
name persons or subjects
(anomia)
• Can utter automatic
speech (“hello”)
• Comprehension relatively
intact
• Most also have partial
paralysis of one side of
the body (hemiplegia)
• If extensive, not much
recovery over time
Clinical Aphasia Classifications

Wernicke’s (cortical sensory) - fluent prosodic speech with
little or no real content


[Examiner: “What kind of work have you
done?”] We, the kids, all of us, and I, we
were working for a long time in the … you
know … it’s the kind of space, I mean
place rear to the spedwan … [Examiner:
“Excuse me, but I wanted to know what
work you have been doing”] If you had
said that, we had said that, poomer, near
the fortunate, forpunate, tampoo, all
around the fourth of martz. Oh, I get all
confused.
Well, this is … mother is away here
working, out o’here to get her better, but
when she’s working, the two boys looking
in the other part. One their small tile into
her time here. She’s working another
time because she’s getting, too.
Clinical Aphasia Classifications

Wernicke’s (cortical sensory) - fluent prosodic speech with
little or no real content
• Fluent but “empty” speech
• But contains many paraphasias
– “girl”-“curl”, “bread”-“cake”
• Grammatical inflections
• Normal prosody
• Syntactical but empty sentences
• Cannot repeat words or sentences
• Unable to understand what they
read or hear
• Usually no partial paralysis
Clinical Aphasia Classifications

Conduction - fluent speech with good comprehension but
impaired repetition and many phonological errors; subcortical
pathway between Broca’s and Wernicke’s areas disrupted
Clinical Aphasia Classifications
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Broca’s (cortical motor) - slow, effortful halting speech,
lacking grammatical words
Wernicke’s (cortical sensory) - fluent prosodic speech with
little or no real content
Conduction - fluent speech with good comprehension but
impaired repetition and many phonological errors; subcortical
pathway between Broca’s and Wernicke’s areas disrupted
Global - broad language impairment across all facets of
language; associated with broad lessions
Anomic -word finding difficulties; lesions often localized
between temporal and parietal lobes
Others: Transcortical motor, Transcortical sensory, Mixed
transcortical
Linguistic Theory and Aphasia
Broca’s aphasia
Wernicke’s aphasia
Vocal tract
instructions
Phonological
structure
Auditory
patterns
Syntactic
structure
LANGUAGE
Thought
Wernicke-Geschwind Model
1. Repeating a spoken word

Arcuate fasciculus is the bridge from the Wernicke’s
area to the Broca’s area
Wernicke-Geschwind Model
2. Repeating a written word

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Angular gyrus is the gateway from visual cortex to Wernicke’s
area
This is an oversimplification of the issue:
 not all patients show such predicted behavior (Howard, 1997)
Some problems with the
classifications

Under careful study many of the deficits aren’t quite
so clear cut:
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Broca’s aphasics have comprehension difficulties that are
similar to their production problems (but can often
compensate for grammatical deficits in comprehension using
semantic context)
~10% of Broca’s aphasics demonstrate Wernicke-like
deficits
The classifications typically don’t take linguistic (and
psycholinguistic) theories into account
Methodologies
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Autopsy
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Wait until an aphasic died, then examine
their brain
fMRI (functional Magnetic Resonance
Imaging)
fMRI
Methodologies
Autopsy
 fMRI (functional Magnetic Resonance
Imaging)
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PET (Positron Emission Tomolgraphy)
PET
hearing
speaking
reading
thinking and speaking
PET by Posner and Raichle
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Passive hearing of words activates:
 Temporal lobes
Repeating words activates:
 Both motor cortices, the supplemental motor cortex,
portion of cerebellum, insular cortex
While reading and repeating:
 No activation in Broca’s area
But if semantic association:
 All language areas including Broca’s area
Native speaker of Italian and English:
 Slightly different regions
 Due to phonetic alphabet of Italian… (“ghotia”)
PET by Damasio’s
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Different areas of left hemisphere (other than Broca’s and
Wernicke’s regions) are used to name (1) tools, (2) animals, and
(3) persons
Stroke studies support this claim
Three different regions in temporal lobe are used
ERP studies support that word meaning are on temporal lobe
(may originate from Wernicke’s area):
 “the man started the car engine and stepped on the
pancake”
 Takes longer to process if grammar is involved
Methodologies
Autopsy
 fMRI (functional Magnetic Resonance
Imaging)
 PET (Positron Emission Tomolgraphy)
 ERP (Evoked Response Potential)

ERPs
Methodologies
Autopsy
 fMRI (functional Magnetic Resonance
Imaging)
 PET (Positron Emission Tomolgraphy)
 ERP (Evoked Response Potential)

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Direct stimulation (Penfield technique)
Direct Stimulation
Gee, this…….
feels kinda’
Electrical Stimulation

Penfield and Roberts (1959): During epilepsy
surgery under local anesthesia to locate
cortical language areas, stimulation of:

Large anterior zone:
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Both anterior and posterior temporoparietal cortex:
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stops speech
misnaming, impaired imitation of words
Broca’s area:
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unable comprehend auditory and visual semantic
material,
inability to follow oral commands, point to objects, and
understand written questions
Studies by Ojemann et al.
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Stimulation of the brain of an English-Spanish bilingual shows
different areas for each language
Stim of inferior premotor frontal cortex:
 Arrests speech, impairs all facial movements
Stim of areas in inferior, frontal, temporal, parietal cortex:
 Impairs sequential facial movements, phoneme identification
Stim of other areas:
 lead to memory errors and reading errors
Stim of thalamus during verbal input:
 increased accuracy of subsequent recall