Behavioral Research Methodsof 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, tests are notoriously bad measures of memory

General Tests ofLanguage 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 green square”

General Tests ofLanguage 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 ofLanguage 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 ofLanguage Function

General Tests ofLanguage 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 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 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 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)

Specific Tests of Frontal Lobe Function

Behavioral Methods ofCognitive 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 drawing 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

Radial Arm Maze

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

Morris Water Maze

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/g2601/0014/2601001473/p1/article.jhtml

• Virtual Operant Conditioning:

http://cayo.net/psy/demolist.html

Review for EXAM 1