Biological Explanations - Neural Correlates

Question 1

Info

Answer 1

• Neural correlates are things like a brain structure or function, etc; measurements of the structure/function of the brain that correlate with an experience
• Both positive and negative symptoms have neural correlates – any abnormality of the ventral striatum may be involved in the development of avolition
• The best known neural correlate is dopamine – important in the functioning of several brain systems related to the symptoms of schizophrenia

Question 2

Juckel et al (2006)

Answer 2

• Measured activity levels in the ventral striatum in schizophrenia and found lower levels of activity than those observed in controls
• Observed negative correlation between activity levels in the ventral striatum and the severity of overall negative symptoms

Question 3

Allen et al (2007)

Answer 3

• Scanned the brains of patients experiencing auditory hallucinations and compared them to a control group whilst they identified pre-recorded speech as theirs/others
• Lower activation levels in the superior temporal gyrus and anterior cingulate gyrus were found in the hallucination group, who also made more errors than the group – reduced activity in these 2 areas is a neural correlate of auditory hallucination

Question 4

OG Dopamine Hypothesis

Answer 4

• Based on the discovery that drugs used to treat schizophrenia (antipsychotics) caused symptoms similar to those in people with Parkinson’s disease, a condition associated with low dopamine levels (Seeman in 1987)
• Schizophrenia might be the result of high levels of dopamine (hyperdopaminergia) in subcortical areas of the brain
• An excess of dopamine receptors in pathways from the subcortex to Broca’s area may explain specific symptoms of schizophrenia like speech poverty/auditory hallucinations

Question 5

Updates

Answer 5

• Davis et al (1991) proposed the addition of cortical hypodopaminergia (abnormally low dopamine in brain’s cortex), which can also explain symptoms of schizophrenia – low dopamine in prefrontal cortex could explain cognitive problems; it has been suggested that cortical hypodopaminergia leads to subcortical hyperdopaminergia
• Genetic variations and early experiences of stress (both psychological and physical), make some people more sensitive to cortical hypodopaminergia and therefore subcortical hyperdopaminergia (Howes et al in 2017)

Question 6

Evaluation - Support for the idea that dopamine is involved

Answer 6

• Amphetamines increase dopamine and worsen symptoms in people with schizophrenia and induce symptoms in people without (Curran et al in 2004)
• Anti-psychotic drugs reduce dopamine activity and also reduce symptom intensity (Tauscher et al in 2014)
• Some candidate genes act on production of dopamine/dopamine receptors

Question 7

Evaluation - Evidence for a central role of glutamate

Answer 7

• 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 in 2020)
• Several candidate genes are believed to be involved in glutamate production/processing

Question 8

Role of prefrontal cortex

Answer 8

• Many schizophrenics have lower activity in this area, which could be linked to delusions and disorganised thoughts

Question 9

Role of visual and auditory cortexes

Answer 9

• Schizophrenics have the same activity in these areas when they hallucinate as sane people do when they have genuine visual and auditory experiences

Question 10

Role of basal ganglia

Answer 10

• Research has shown that this structure is larger in schizophrenics, which could cause motor dysfunction

Question 11

Role of amygdala

Answer 11

• Smaller in schizophrenics so it can link to loss of emotion (affective flattening)

Question 12

Role of dopamine

Answer 12

• Low levels in certain brain areas are linked to negative symptoms as these are linked to a loss of pleasure
• High levels in brain areas are linked to positive symptoms