Neural Correlates Flashcards
Neural Correlates.
Patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience.
Dopamine.
Neurotransmitter - an excitatory effect and linked to the sensation of pleasure.
Usually, high levels are linked with schiz and unusually low levels are linked with Parkinson’s disease.
Original Dopamine Hypothesis.
Based on the discovery that drugs used to treat schiz (antipsychotics, reduces DA) caused symptoms similar to those in people with Parkinson’s disease, a condition with low levels of DA in subcortical areas.
Updated version of the Dopamine Hypothesis.
Davis et al (1991) proposed the addition of cortical hypodpaminergia (abnormally low levels of DA) in cortex; explains symptoms of schiz.
Current versions also try to explain the origins of abnormal DA functions, so it seems that both genetic variations and early experiences of stress, both psychological and physical, make some ppl more sensitive to cortical hypodapimenrgia and hence subcortical hypendopaminergia (Howes et al 2017).
Hyperdopaminergia in the subcortex.
The original version of the hypothesis.
focuses on the possible role of high levels or activity of dopamine in the subcortex.
Hypodopaminergia in the cortex.
More recent version of the hypothesis.
Focused on abnormal dopamine systems in the brain cortex - particularly the pre-frontal cortex, which is responsible for thinking and decision making - this could explain negative symptoms.
Strength: There is support for the idea that dopamine is involved in schizophrenia.
First, amphetamines increase DA and worsen symptoms in ppl with schizophrenia and reduce symptoms in people without (Curran et al 2004).
Second, antipsychotic drugs reduce DA activity and also reduce the intensity of symptoms (Tauscher et al 2014).
Third, some candidate genes act on the production of DA or DA receptors.
This strongly suggests that dopamine is involved in the symptoms of schizophrenia.
Limitation: There is evidence for a central role of glutamate in the dopamine hypothesis.
Post-mortem and live scanning studies have consistently found raised levels of the neurotransmitter glutamate in several brain regions of people with schizophrenia (McCutcheon et al 2020).
In addition, several candidate genes for schizophrenia are believed to be involved in glutamate production or processing.
This means that an equally strong case can be made for a role for other neurotransmitters.
Strength: The dopamine hypothesis is that it has practical applications which led to the development of an effective treatment.
From the research using schizophrenics, new drugs have been developed such as Clozapine, which is much more effective than neuroleptics at relieving schizophrenic behaviour. This suggests that psychiatrists can understand the role played by neurotransmitters when treating different types of schizophrenia and thus improve the patient’s quality of life.
