dopamine hypothesis explanation A01 Flashcards
what does the dopamine hypothesis claim?
it claims than an excess of dopamine in certain regions of the brain is linked to positive symptoms of schizophrenia such as delusions and hallucinations.
what are schizophrenics thought to have high numbers of?
D2 receptors on neurons
how do high levels of D2 receptors lead to delusions and hallucinations?
more neurons- fire more often and in high numbers - more dopamine- leads to the delusions and hallucinations.
in what two sources of evidence are the two key roles played by dopamine highlighted?
drugs that increase and decrease dopaminergic activities.
state another term for amphetamine?
speed
what is amphetamine?
a dopamine antagonist
how does amphetamine increase dopaminergic activity?
it stimulates the nerve cells containing dopamine and floods the synapse with dopamine.
how does amphetamines lead to schizophrenic symptoms?
large doses of it, can develop into delusions and hallucinations
what did Grilly find?
he found that people suffering from certain endocrine diseases who take dopamine releasing drugs, other than amphetamine, have been found to develop schizophrenic symptoms.
what do antipsychotic drugs do?
block the activity of dopamine in the brain
how do antipsychotics reduce schizophrenic symptoms?
they reduce activity in neural pathways and so eliminate positive symptoms of delusions and hallucinations.
who developed the revised dopamine hypothesis?
Davis and Khan
what did Davis and Khan propose?
that positive symptoms are caused by excess of dopamine in the mesolimbic pathway and the negative/cognitive symptoms are caused from a lack of dopamine in the mesocortical pathway.
what are two pieces of evidence for Davis and Khan’s revised dopamine hypothesis?
neural imaging and animal studies
how did Patel et al use neural imaging to show evidence for Davis and Khan’s theory?
he used PET scans to assess dopamine levels in sz and non sz people and found lower levels of dopamine in the mesocortical pathway found in the prefrontal cortex in sz people.
