PSYCH261 Lecture Notes - Lecture 4: Electric Field, Microdialysis, Bregma
15 Oct 2018
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Recall: physiological psychology is that aspect of psychological science that seeks to establish
the relationship between brain and behaviour.
● the research methods are the practical, physical connection that allow us to go from our
knowledge of brain structure and brain physiology to an understanding of how that
produces psychological behaviour.
Research Methods in Physiological Psychology:
● research methods can be broken into several large groups:
○ experimental ablation
■ removing a piece of the brain or the nervous system
○ recording and stimulating neural activity
■ neuroimaging methods
■ methods of cellular physiology
■ neurochemistry
■ neurogenetics
Experimental Ablation:
● making a hole in the brain
○ suck the brain out with a little vacuum - aspiration
○ burn it with electricity or excessive temperature
● doing structural damage to some small area of the brain
● logic: make an association between the function of an area by observing the
consequences of damage to it.
○ complex behaviour are rarely produced by single areas of the brain but rather
more than one which is a complication.
○ also we can damage fibres and falsely assume that one part of the brain is
responsible for a behaviour when it may not be.
● there are ways to address some of these concerns:
○ excitotoxic lesion: a brain lesion produced by intracerebral injection of an
excitatory amino acid, such as kainic acid.
■ some neurotransmitters are excitatory
■ excessive stimulation of the receptors of these transmitters occurs it can
actually damage or kill the neurons that are stimulated.
■ kainic acid: common excitotoxic agents - used and has the advantage
that it acts on cell bodies, so it kills only the cells that are at the location of
the injection and does not damage fibres that pass through the region.
○ we can also use neurotransmitter stimulants that effect particular neuronal
populations that are much more restricted in terms of their transmitter content
■ 6-Hydroxydopamine (6HD): chemical that is taken by axons and terminal
buttons of noradrenergic or dopaminergic neurons and acts as a poison,
damaging or killing them.
● Ablation - taking out a piece of the brain and although there are many different methods
to do this
○ all methods make the inference that we will be able to understand the function of
a piece of the brain by observing behaviour of an animal and how that behaviour
is changed after a lesion has been produced.
How to Place an Accurate Lesion:
● stereotaxis: location deep structures within the brain by their relationship to superficial
landmarks typically found on the skull.
○ use in animal experiments - purposely being used to guide the damage or
destruction of a brain region.
■ e.g. rats
○ also used in human neurosurgery.
● landmarks include skull features
○ bregma: a common anatomical landmark used in stereotaxic apparatus.
■ where the different bones of the skull form together - called a sutures.
■ connection of several suture lines form the bregma.
■ this looks like a plus sign in the middle of the skull.
● use atlases to turn the distances from these skull landmarks into locations of the brain
structure.
○ calibrates in cm or mm
○ stated in reference to the skull landmarks that are used on the stereotaxic
apparatus.
● how are we supposed to know whether our changes in behaviour are duets the small
area deep within the brain that we have lesioned as opposed to other damage we could
have caused when getting the lesion in place?
○ Sham surgery: use as an experimental control
○ if we do all the experimental preparation except for the actual lesion, we can
compare those animals who have the same preparation and the lesion.
■ can make the deduction that differences between these two cohorts are
not due to any accidental damage caused during preparation of the
lesion.
■ the damage would only be due to the damage which was caused
specifically by experimental ablation.
Histological Methods;
● may wonder: if changes in the structure of their brain are in part the basis for our
observed behavioural difference.
○ brain under a microscope - field of histology: study of tissues.
○ microtome: used to slice brain tissue and preparing microscopic slides.
○ able to see more individual nerve cells or nerve grouping, nuclei etc. when
stained.
● after the brain is removed from the animal:
Document Summary
Research methods in physiological psychology: research methods can be broken into several large groups: removing a piece of the brain or the nervous system. Experimental ablation recording and stimulating neural activity. Suck the brain out with a little vacuum - aspiration. Burn it with electricity or excessive temperature. Doing structural damage to some small area of the brain logic: make an association between the function of an area by observing the consequences of damage to it. Complex behaviour are rarely produced by single areas of the brain but rather more than one which is a complication. Also we can damage fibres and falsely assume that one part of the brain is responsible for a behaviour when it may not be. there are ways to address some of these concerns: Excitotoxic lesion: a brain lesion produced by intracerebral injection of an excitatory amino acid, such as kainic acid.
