Daniel (key study) (psychological problems)

Question 1

What was the background?

Answer 1

• Studies had shown low levels of activity in the prefrontal cortexes of people with schizophrenia. This was linked to the activity of dopamine in the brain.
• Studies had suggested that dopamine is important in suppressing random brain activity and helping to focus on specific stimuli in the environment.

Question 2

What is an agonist?

Answer 2

A substance that stimulates dopamine activity

Question 3

What was the hypothesis?

Answer 3

If dysfunction in the prefrontal cortex was related to problems in dopamine-controlled synaptic transmission, then an agonist should increase activity in that area during a cognitive task.

Question 4

How did the researchers scan the participants brain activity?

Answer 4

They scanned the brain using SPECT (single photon emission computed tomography)

Question 5

What is the Wisconsin card sorting test?

Answer 5

• A game where a participant has a card with pictures of a shape and must match it to another card.
• They must match it by either shape, colour, or number of shapes.
• They do not know what rule they must use to match the card, they figure it out by trial and error
• The rule can randomly change throughout the test
• The main objective is to measure the subject’s ability to shift cognitive strategies in response to changing environmental demands.

Question 6

What was the dependent variable?

Answer 6

Performance on the Wisconsin card sorting test

Question 7

What was the independent variable?

Answer 7

Whether the participant had been given amphetamine or not

Question 8

What was the sample?

Answer 8

• 10 in-patients from the national institute of mental health research in Washington, USA
• All had chronic schizophrenia
• Clinically stable enough to cooperate
• Free of any other illnesses as well as alcohol and drugs

Question 9

What were the ethical conditions?

Answer 9

• The radiation safety committee had approved the study
• All participants had given informed consent

Question 10

What were the materials?

Answer 10

• SPECT scanner
• Simple sensori-motor control test (The BAR task, where participants match bars on a screen based on their orientation)
• Prefrontal activation test (WCST)

Question 11

What was the procedure?

Answer 11

• Participants were on haloperidol to stabilise them for at least 6 weeks before the experiment.
• 5 participants did the BAR task first and 5 did the WCST first (counterbalancing)
• On the 2 test days, each participant either received a dose of amphetamine or a placebo, in an order that was counterbalanced.
• Both tasks were carried out on a computer and required similar motor responses.

Question 12

What were the results?

Answer 12

• Amphetamine had a minimal effect on regional cerebral blood flow when participants completed both the BAR task and WCST.
• There was no significant differences in the effects of the amphetamine and the placebo on brain activity when completing the BAR task.
• There were some significant differences in the blood flow in particular regions of the brain when completing the WCST
• Amphetamine had a small but significant positive effect on two performance measures of the WCST, including the number of correct responses. There was no such effect when the placebo was used.
• Behaviour changes caused by the amphetamine were highly variable and generally mild, ranging from increased cooperation, optimism, and mood, to irritability and dysphoria. 3 patients showed significant improvement and one patient significantly deteriorated.

Question 13

What were the conclusions?

Answer 13

• Amphetamine significantly increased prefrontal cortex activity during performance of a cognitive task, despite reducing bloodflow to the brain.
• Showed a link between brain function and key symptoms of schizophrenia.
• Supports biological theory

Question 14

What were the criticisms?

Answer 14

• Sample size was too small to be generalisable.
• Participants were all volunteers so not representative of all people with schizophrenia.
• The sample was culturally biased as they were all from the USA and 8/10 participants were white. Different ethnic groups have different rates of schizophrenia.
• Using scans on participants with a placebo is unethical as they are subjected to harmful radiation.
• The difference in brain activity may have been affected by the haloperidol give to the participants beforehand. (it was used to stabilise the patients)