Schizophrenia - Basic Dopamine Hypothesis, D2 Pathways, and S+Ws

Question 1

What does the basic dopamine hypothesis suggest causes schizophrenia?

Answer 1

Basic dopamine hypothesis suggests that, in a normal brain, dopamine is released at the presynaptic membrane and uptaken by dopamine receptors on the postsynaptic membrane, excess being reuptaken by the presynaptic membrane. In a schizophrenic brain, there are too many dopamine receptors on the postsynaptic membrane, resulting in the over-receptivity of dopamine, with excess not being reuptaken. This leads to the symptoms of schizophrenia

Question 2

What does the D2 hypothesis hypothesis suggest causes schizophrenia?

Answer 2

The D2 hypothesis suggests that the brain contains multiple pathways for dopamine. If too much dopamine is present in the mesolimbic pathway, this creates positive schizophrenic symptoms. If too little dopamine is present in the mesocortical pathway, this contributes to negative schizophrenic symptoms

Question 3

+ Supported with research evidence

Answer 3

One strength of neurotransmitters and schizophrenia is that it is supported by the evidence of Randup and Mankvad, who raised the dopamine levels of rats by injecting them with amphetamine, the rats showing positive symptoms of psychosis. This shows a cause and effect between dopamine and psychosis, validating the theory

Question 4

+ Blocking D2 receptors

Answer 4

Blocking D2 receptors in the mesolimbic pathway reduces the positive symptoms of schizophrenia - supports theory in validating idea that blocking dopamine reduces schizophrenia symptoms in mesolimbic pathway

Question 5

• 4 pathways in new research

Answer 5

More up-to-date research is starting to show that there are possibly 4 pathways in the brain involved with SZ, and understanding of SZ will improve as we understand the brain to a greater extent - suggests D2 theory is reducitonist as there are a greater number of pathways han suggested by hypothesis

Question 6

• Glutomate

Answer 6

Another neurotransmitter, glutamate, is also thought to cause psychotic symptoms is production is blocked - suggests dopamine hypothesis ignores other factors leading to psychosis, suggesting theory is too reductionist and simplistic