L5: Biological Explanations - Neural Correlates Including The Dopamine Hypothesis

Question 1

The dopamine hypothesis: What neurotransmitter do Schiz patients have a lot of? What does it do?

Answer 1

Dopamine - increases firing of neurones

Question 2

The dopamine hypothesis: What drug decreases dopamine?

Answer 2

Phenothiazine - block dopamine at synapses

Reducing positive symptoms but no change for negative symptoms

Question 3

The dopamine hypothesis: What drug increases dopamine?

Answer 3

L Dopa

• induces symptoms of Schiz and has been tested on normal people
• drugs like LSD/Amphetamines increase dopamine levels - can induce Schiz symptoms

Question 4

The dopamine hypothesis: What is the dopamine hypothesis based on?

Answer 4

• Post mortem studies show more dopamine receptors in the left amygdala
• Dopamine metabolism is abnormal in patients - monitored by PET Scans
• Dopamine hypothesis might be linked to fault in genes, causing levels of dopamine to increase dramatically

Question 5

The dopamine hypothesis: Evaluation

Answer 5

(+) Scientific study showed that when Schiz patients were given L-Dopa, symptoms got worse
(+) Most evidence is scientific and has used evidence from brain scans which is valid and reliable
(-) Cause and Effect not established
(-) Dopamine is associated with Schiz and mania. This illness is not alleviated by phenothiazine. Dopamine has a complex role and is associated with many psych disorders
(-) Reductionist: takes complicated phenomenon of causes of Schiz and only suggests dopamine. Other factors are ignored

Question 6

Neural Correlates: Why might Schiz develop?

Answer 6

• Structural and functional brain abnormalities
• Post mortem were used but now we use fMRI
• Patients w/ and w/out Schiz were put on fMRI and told to do tasks (cognitive/memory)

Question 7

Neural Correlates: What did Swayze do?

Answer 7

• Reviewed 50 studies of Schiz patients and examined their Brain using fMRI
• Found that patients have structural abnormalities
  (=) Decrease in brain weight
  (=) Enlarged Ventricles
  (=) Smaller hypothalamus
  (=) Less grey matter
  (=) Structural abnormalities in prefrontal cortex

Question 8

Neural Correlates: Evaluation

Answer 8

(-) Psychologist critiqued neural correlates. He found the extent to which the ventricles are enlarged are not significant. There is little difference between the neural correlates of a patient and a normal person
(-) Cause/Effect
(-) Contradictory evidence - enlarged brain ventricles present in mania and Schiz patients. Therefore enlarged ventricles can’t cause Schiz but could be a vulnerability factor
(+/-) Evidence that Schiz is caused by neural correlated changing during pre-natal development, does not explain why Schiz occurs in early adulthood. A psychologist stated that the prefrontal cortex develops during adolescence so would only be noticed then