Neuro 5.pdf

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Published on 22 Apr 2013
School
McGill University
Department
Psychology
Course
PSYC 211
1
PSYC 211
Neurobiological Methods
of Research
Dr. Yogita Chudasama
Stewart Biology, Room N8/4
Experimental approaches to understanding behaviour
!Invasive physiological research methods
(lesion, electrical stimulation, neurophysiological recording)
!Behavioral paradigms that assess constituent cognitive processes
(visuospatial attention, working memory, reversal learning)
!Pharmacological research methods
(drug adminstration, chemical lesions, chemical activity of the brain)
!Genetic engineering
(gene knockout, genetic replacement)
!Visualising the living human brain
(PET, FMRI)
!Neuropsychological testing
(WCST, delayed response)
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Experimental Ablation (Lesion Methods)
!Experimental ablation
A method used to investigate brain function by destroying part of the
brain and evaluating the animals subsequent behaviour.
!The area of the brain that is damaged is called the brain lesion.
!The goal of lesion methods is to discover what functions are performed
by different regions of the brain and how these functions are organised
to produce complex behaviour (i.e functional organisation of the brain).
!Neural circuits in the brain perform functions (or a set of functions).
!Functions contribute to the performance of a behaviour.
Brain Stereotaxy
Stereotaxic surgery is a form of surgical
intervention. It uses a three dimensional
coordinate system to locate a target brain
region and perform the lesion.
A stereotaxic atlas contains drawings that
correspond to brain sections taken at
varying distances from bregma.
No two brains of any given species are
identical.
The skull is made up of several bones
that join together and form sutures. The
junction at which the sutures meet at the
front of the head is called bregma. The
junction at the at which the sutures meet
at the back of the head is called lambda.
The skull of a rat brain
A page from a stereotaxic atlas of the rat
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Stereotaxic apparatus for performing
brain surgery in rats
Injector
Skull
Adjusting knobs
!Inject excitotoxins to create
selective lesions to specific
brain areas
!Create neurochemical lesions
(e.g. deplete acetylcholine in
the frontal cortex)
!We can use it to place wires to
stimulate neurons
!We can implant cannulae that
allow the infusion of drugs that
temporarily stimulate neurons
or block specific receptors
Different Lesion Methods (I)
Excitotoxic lesions
!An excitatory amino acid (e.g. ibotenic acid, kainic acid, N-methyl-d-
aspartic acid) is injected into the target region of the brain.
!The chemical destroys cell bodies (the somas) by stimulating them to
death.
!This method is highly selective; it destroys cell bodies only, and spares
axons of other neurons that pass nearby (fibres of passage).
!This method can create selective neurochemical lesions thereby depleting
dopamine, serotonin, norepinephrine or acetylcholine in specific brain
areas.
Aspiration lesions
!The brain area of interest is removed by suction (or aspiration) using a
fine-tipped hand-held glass pipette.
!Can be performed under visual guidance.
!This method can sometimes damage underlying white matter and major
blood vessels.
!This is a nonselective method because it removes cell bodies and fibres of
passage.
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Document Summary

Invasive physiological research methods (lesion, electrical stimulation, neurophysiological recording) Behavioral paradigms that assess constituent cognitive processes (visuospatial attention, working memory, reversal learning) Pharmacological research methods (drug adminstration, chemical lesions, chemical activity of the brain) A method used to investigate brain function by destroying part of the brain and evaluating the animals subsequent behaviour. The area of the brain that is damaged is called the brain lesion. The goal of lesion methods is to discover what functions are performed by different regions of the brain and how these functions are organised to produce complex behaviour (i. e functional organisation of the brain). Neural circuits in the brain perform functions (or a set of functions). Functions contribute to the performance of a behaviour. No two brains of any given species are identical. The skull is made up of several bones that join together and form sutures. The junction at which the sutures meet at the front of the head is called bregma.

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