Biological Explanation - Dopamine Hypothesis

Question 1

Explain the initial hypothesis…

Answer 1

Proposed that schizophrenics had too much dopamine

Supported by J.J.Griffith (1968) where he was able to induce psychosis in volunteers through administering dextro-amphetamine

To simple as administering drugs to reduce dopamine levels had little to no effect in those suffering with negative symptoms

Question 2

Explain dopamine receptor sites…

Answer 2

Several sub-types of sites discovered (D1-D5) distributed in the cerebral cortex and limbic system

Particular interest in D2 receptor sites, as research (Seeman and Lee, 1975) had shown the impact of antipsychotic drugs on the type of receptor

Question 3

Explain the limbic system…

Answer 3

Consists of subcortical pathways engaged in many functions i.e., the mesolimbic and mesocortical pathways

Question 4

Explain the mesolimbic pathway…

Answer 4

Pathway carries signals from the ventral tegmental area to the nucleus accumbens, where too much dopamine causes overstimulation and positive symptoms. Anti-psychotic drugs reduce dopaminergic neurotransmission, reducing positive symptoms

Question 5

Explain the mesocortical pathway…

Answer 5

Pathway carries signals from the ventral tegmental area to the frontal lobe, which is vital in emotional responses, cognition and motivation. Kenneth Davis et al. (1991) found that too little dopamine in D1 receptors leads to negative symptoms