Download Behavioral Research Methods of Biopsychology

Behavioral Research Methods
of Biopsychology
Ch. 5 (cont’d)
Outline
(1) Summary of Previous Lecture
(2) Neuropsychological Testing
(3) Behavioral Methods of Cognitive
Neuroscience
(4) Paradigms of Animal Behavior
(5) Conclusion: Converging Operations
Summary of Previous Lecture
• Methods of Visualizing the Living Human
Brain
• Recording Psychophysiological Signals
• Invasive Physiological and Pharmocological
Methods
• Genetic Engineering
Neuropsychological testing
Neuropsychological testing
• Methods used to assess psychological deficits of
human patients suspected of having brain damage
• Traditionally, a single neuropsychological test
was administered to a patient; this approach
changed in the 1960’s to include a standard
battery of neuropsychological tests; currently, it is
most common for a customized-test-battery
approach to be used
General tests: The WAIS
• Most neuropsychological assessments begin with
the Weschler Adult Intelligence Scale (WAIS)
• It has 11 subtests; 6 comprise the verbal scale
(e.g., digit span, information, similariites); 5
compromise the performance scale (e.g., block
design, object assembly)
• The information subtest and the digit span test
are memory tests that comprise part of the WAIS;
however, test are notoriously bad measures of
memory
General Tests of
Language Function
• The WAIS verbal subtests reveal significant
language impairments in a variety of ways; if the
WAIS was not done, the token test is a good initial
screening test for language-related deficits; there
are 20 tokens of 2 different shapes, 2 different
sizes, and 5 different colors; the subject is asked to
carry out various acts such as “touch the small
blue circle and then the large gree square”
General Tests of
Language Function
• If the token test identifies language deficits,
it is followed by a battery of tests of
language ability
• A test for the lateralization of language
skills is also often included when assessing
language function
General Tests of
Language Function
• In the sodium amytal test, the anesthetic
sodium amytal is injected first into one
carotid artery and then, many minutes
later, into the other; typically the patient is
mute following an injection ipsilateral to the
dominant hemisphere for language but
makes only a few minor speech errors after
an injection contralateral to the dominant
hemisphere for language
General Tests of
Language Function
• In the dichotic listening test, three pairs of
digits are presented to the subject through
headphones; each digit in the pair is
presented simultaneously, one to each ear;
the subjects are asked to report the six digits
than they heard; they do slightly better
through the ear contralateral to the
hemisphere dominant for language
Specific Tests of Memory
•
If memory deficits are discovered, the
neuropsychologist attempts to answer 4
key questions:
(1) Is short-term or long-term memory affected? Or both?
(2) Are the deficits anterograde or retrograde? Or both?
(3) Do the deficits involve semantic or episodic memory?
Or both?
(4) Do the deficits involve explicit memory or implicit
memory? Or both?
Specific Tests of Language
• If language deficits are discovered, the
neuropsychologist attempts to determine
whether the problem is one of phonology
(understanding the rules for the sounds of
language); of syntax (grammar); or of
semantics (meaning)
Specific Test of Frontal Lobe
Function
• The Wisconsin Card Sorting Test is often used to
asses fromtal lobe function
• Each card in the deck has 1, 2, 3, or 4 triangles,
circles squares, or crosses that are all red, green,
yellow, or blue
• The subject is told to sort the cards into four
different piles but not told on what basis the
sorting is to be accomplished; they are told after
each card is placed in a pile whether or not it was
correctly placed
Specific Tests of Frontal Lobe
Function
• At first the patient must learn to sort by color, but
once she or he has learned this sorting principle,
the correct principle changes w/o warning to form
or number
• Patients with frontal-lobe lesions adapt poorly to
rules changes; they perseverate (they continue to
respond in a previously correct fashion long after
it has become incorrect)
Behavioral Methods of
Cognitive Neuroscience
Assumption of constituent
cognitive processes
• The premise that complex cognitive processes are
the combined activity of simple cognitive
processes and that each constituent cognitive
process is mediated by neural activity in a
particular area of the brain
• Cognitive psychologists, computer scientists, and
neuroscientists combine efforts to model complex
cognitive processes, for clinical as well as
artificial intelligence application
Paired-image subtraction
techniques
• A key imaging technique in cognitive
neuroscience research
• PET or fMRI images of tasks that differ in only
one constituent cognitive process are compared;
the difference between the two images is viewed
as specific to the one constituent cognitive process
that was different between the two images
Paired-image subtraction
techniques
• Example: if interested in cognition of
writing, take an fMRI of subject just
drawing circles. Then an fMRI of the
subject writing meaningful sentences is
taken. Activity on the fMRI associated with
rawing circles is then subtracted from that
of writing sentences.
Paired-image subtraction
techniques
• Signal averaging is often used to reduce the
noise associated with random cerebral
events
Animal Behavior Paradigms
Traditional Conditioning
Paradigms
•
Traditional conditioning paradigms play an
important role in biopsychology for three
reasons:
(1) Conditioning is a phenomenon of primary
interest to psychologists
(2) Conditioning procedures are often used to train
laboratory animals to perform as required in
behavioral experiments
(3) Researchers can infer much about the
psychological state of an animal from its ability
to learn and perform various responses
Traditional Conditioning
Paradigms
• Pavlovian conditioning: in which a neutral
stimulus called a conditional stimulus (tone) is
paired with an unconditional stimulus (meat) that
elicits an unconditional response (salivation)
• As the CS becomes associated with the US, it
begins to elicitt a response on its own which is
referred to as conditional response (CR). The CR
is similar to the UR, but this is not always the case
Traditional Conditioning
Paradigms
• Operant Conditioning: in which the rate of
a particular response is
increased by reinforcement
or decreased by punishment
Semi-natural Animal Learning
Paradigms
• Ethoexperimental animal learning
paradigms are controlled laboratory
paradigms for studying forms of learning
that are assumed to occur in the rat’s natural
environment
Semi-natural Animal Learning
Paradigms
• Examples:
– Radial Arm Maze
– Morris Water Maze
Semi-natural Animal Learning
Paradigms
• Radial-Arm Maze:
– Is used to study foraging behavior in the laboratory
– Foraging in the wild is complex; the rat must learn
where the food is likely to be, but not to immediately
revisit a stripped site
– In the radial arm maze rats quickly learn to go directly
to the arms that are baited with food each day, but the
rarely visit the same arm twice on a given trial
Semi-natural Animal Learning
Paradigms
• Morris Water Maze:
– Is another laboratory paradigm used to study rat spatial
ability; the Morris water maze is a large tub of milky
water; to get out of the water, rats must learn to swim to
a slightly submerged (invisible) goal platform
– Rats learn to do this very quickly, even when they are
placed in the water at a different position on each trial;
they use external room cues to guide them
– It is interesting to look at their search strategies when
the platform has been moved to a new location
Conclusion:
Convergent Operations
• You have now learned about many research
methods used by biopsychologists; they all have
their strengths, but they all have their weaknesses
• The key to scientific progress lies in converging
operations (bringing several methods to bear on
the same problem so that each compensates for the
shortcoming of the others)
Websites
• The Weschler Intelligence Scales:
http://www.findarticles.com/cf_dls/g2601/0014/2601
001473/p1/article.jhtml
• Virtual Operant Conditioning:
http://cayo.net/psy/demolist.html
Review for EXAM 1