ABLATION & LESION STUDIES IN PSYCHOLOGY

1. METHODS OF STUDY: ABLATION & LESION
-ASHISH BUDHWAR

2. PHYSIOLOGICAL PSYCHOLOGY
 It is that branch of
psychology that
connects behavior &
other mental processes
like emotions, feelings &
thinking to bodily
processes & specifically
to the processes of the
brain & the nervous
system.

3. METHODS OF RESEARCH IN
PHYSIOLOGICAL PSYCHOLOGY
 ABLATION AND LESION STUDIES
 ELECTROENCEPHALOGY (E.E.G)
 MAGNETOENCEPHALOGY (M.E.G)
 BRAIN STIMULATION
 IMAGING TECHNIQUES

4. ABLATION & LESION
 Ablation and Lesion studies are important methods
of research to study the relation between the
functioning of the brain and the behavior of
organisms.
 A lesion in brain of organisms is a damaged part of
the brain that results in the destruction of neurons.
Lesions can come from natural sources like injury,
disease or ageing.
 Ablation is the purposeful creation of a lesion in the
brain in experimental organisms.

5. ABLATION AND LESION
 Damage/Lesion in a part of brain can produce
different behavioral and psychological effects.
 For example,
1. Damage to the front end of the brain can disturb
the ability to make decisions and to inhibit socially
inappropriate behaviors.
2. Damage to the back of the brain disturbs the vision.

6. RATIONALE BEHIND THE METHOD
 The rationale behind the method of ablation is that;
after a particular lesion occurs or is created or
removed, and the organism can no longer perform a
function/behavior which he was performing
previously or there is a change in behavior, an
inference can be made that the area destroyed in
brain is responsible for that particular
function/behavior.

7. LESION STUDIES
 Four types of ablation lesions are discussed here:
1. Aspiration lesions,
2. Radio-frequency lesions,
3. Knife cuts, and
4. Reversible lesions.

8. ASPIRATIONAL LESIONS
 Aspiration is a useful method of lesion when a lesion
is to made in the visible and accessible part of the
brain such as the cortical region. After an incision is
made in the scalp, the cortical tissue is drawn off by
suction through a fine-tipped handheld glass pipette.
 The aspiration method requires great skill as the
underlying white matter in the brain and the blood
vessels are resistant to suction, a skilled surgeon can
delicately peel off the required part without
damaging any blood vessels or the white matter.

9. METHODS OF BRAIN STUDY

10. RADIO FREQUENCY LESIONS
 This method of lesion study is useful when a lesion
has to be made and studied in the subcortical region
of the brain.
 Such lesions are made by passing high frequency
radio currents through the target tissue by a
stereotaxically positioned electrode.
 The heat from the current destroys the tissue.
 Te size and the shape of the lesion is determined by
the duration and the intensity of the current and the
configuration of the electrode tip.

11. KNIFE CUT LESIONS
 This method is useful
in for sub-cortical
lesion studies. It
involves the cutting
or sectioning to cut
off the conduction in
a nerve or a tract.
 It requires great
precision as a tiny,
well-placed cut can
unambiguously
accomplish this task
without producing
extensive damage to
surrounding tissue.

12. REVERSIBLE LESIONS
 Reversible lesions are useful alternatives to
destructive lesions.
 Reversible lesions are methods for temporarily
eliminating the activity in a particular area of the
brain while tests are being conducted.
 The advantage of reversible lesions is that the same
subjects can be repeatedly tested.
 Reversible lesions can be produced by cooling the
target structure or by injecting an anesthetic (e.g.,
lidocaine) into it.

13. INTERPRETING LESION RESULTS
 Lesion effects are deceptively difficult to interpret. Because
the structures of the brain are small, convoluted, and tightly
packed together, even a highly skilled surgeon cannot
completely destroy a structure without producing significant
damage to adjacent structures.
 For example, a lesion that leaves major portions of the
amygdala intact and damages an assortment of neighboring
structures comes to be thought of simplistically as an
amygdala lesion.
 Also care must be taken while interpreting the results of
ablation. It is not easy to determine functions in animals as it
is in humans. For eg: to determine that an animal has become
blind, it will require complex tests, while in humans the
subject can simply speak an tell the effect of the ablation.

14. ETHICAL CONCERNS IN ABLATION
 The method of ablation, destroying brain tissues to
study their functioning, would be unethical in
humans. Therefore experimental organisms whose
body functions and anatomies are similar to humans
are chosen to get a close guess about the human
brain functioning.
 Ablation method can be used as a treatment for
dangerous and damaging disorders of the brain that
can be a threat to an individual such as epileptic
seizures.

15. CONCLUSION
 Since, one part of the brain cannot be responsible for
all behaviors, the aim is to determine what functions
combine up to perform particular behaviors.
 So the procedure, as well as the interpretation of the
results is a very complex task and requires utter care
or else the results can mislead the research.