PSYC10003 Lecture Notes - Lecture 7: Hemoglobin, Fine Structure, Cerebral Circulation
6 Jun 2018
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PSYC10003 – MIND, BRAIN, & BEHAVIOUR 1
BEHAVIOURAL NEUROSCIENCE
Lecture 7 (Week 3 . 1): Methods for Studying the Living Brain
Clinical Neuropsychology: helps diagnose, manage, & treat patients with neurological disorders, &
explain normal brain-behaviour relationships by assessing how the system breaks down after damage
• Works to establish patterns of association & dissociation in the behaviour of brain damaged
individuals, thereby describing the functional modules of perceptual & cognitive processing that have
been affected by the damage, & those that have been spared (which processes work together)
Broca’s aphasia: damage to the L hemi’s posterior part of the inferior frontal gyrus
(Broca’s Area) results in inability to communicate through speech (expressive language)
• Aka non-fluent aphasia, or expressive aphasia
• Patients usually aware of their problems
• Agrammatism: problems in comprehending/using grammatical constructions ( function words, -ed)
• Anomia: difficulty finding (remembering) the appropriate word to describe an object
• Apraxia of speech: impairment in ability to program movements of the tongue, lips, & throat
required to produce the proper sequence of speech sounds
• Comprehension is also compromised to some extent, especially for complex
sentences (e.g. difficulties in using word-order to interpret meaning)
Wernicke’s Aphasia: damage to L hemi’s posterior part of superior temporal gyrus
(Wernicke’s Area) results in difficulty comprehending speech (fluent, but meaningless)
• May use few content words, & often will insert nonsense words or jargon
• Often unaware of their impairment (perhaps b/c they can’t recognise that their speech is faulty)
This dissociation between processes associated with speech production & those associated with
comprehension suggests these abilities represent distinct functional modules of the mind, which also
happen to be subserved by distinct regions of the brain (though this mightn’t always be the case)
Limitations of Clinical Neuropsychology:
• Since brain lesions are ‘accidents of nature’, no two patients will ever have identical brain pathology,
so it’s difficult to replicate experimental findings in other cases
• A key assumption that lesions only affect functions of tissue that’s destroyed, leaving functions of
other areas unaffected (swelling in distant brain sites, change to inputs & outputs of other regions)
• Can’t control the size / location of damage (‘experiments of nature’), & extensive / diffuse damage
makes it impossible to link a particular area of the brain with a particular function
• Patients with brain lesions may have medical problems that prevents intensive testing
Ablation studies in animals: make small lesions in distinct parts of the brain & observe the behavioural
effects (experimental ablation). May be achieved surgically, using radiofrequency energy, or injecting
toxic chemicals to destroy the neurons in a particular area. Strict ethical guidelines
• Allow the location of the lesion to be determined with a fairly high degree of precision
• Was used to determine the role of parts of the limbic system: role of hippocampus, amygdala, &
surrounding cortex in learning & memory
• Delayed non-matching to sample: an experimental task often used to lest learning & memory.
Monkey separated from two food wells by opaque screen. Initially the experimenter hides a food
reward in one well by covering it with a card with a distinctive symbol. Screen’s raised & monkey’s
shown the correct response (retrieves reward). The screen’s lowered again & a food reward hidden
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Document Summary
Ablation studies in animals: make small lesions in distinct parts of the brain & observe the behavioural effects (experimental ablation). May be achieved surgically, using radiofrequency energy, or injecting toxic chemicals to destroy the neurons in a particular area. Monkey separated from two food wells by opaque screen. Initially the experimenter hides a food reward in one well by covering it with a card with a distinctive symbol. Screen"s raised & monkey"s shown the correct response (retrieves reward). The screen"s lowered again & a food reward hidden beneath a card with a different symbol to the first trial. The longer the delay, the more errors (higher rate than with normal). More damage (cid:314) more impairment: limitations: experimental lesion might still affect distant structures in the brain, & many advanced aspects of human cognition can"t be tested in other species (e. g. language & complex reasoning)
