biological approach : dopamine & neural correlates

Question 1

how is dopamine involved?

Answer 1

Dopamine is a substance that is known to be active in the limbic system, an area of the brain governing emotion.

Dopamine neurons are instrumental in regulating attention, therefore if this process is disturbed it may lead to problems with attention, perception and thought – these are all characteristics of schizophrenia.

Question 2

what does the dopamine hypothesis claim?

Answer 2

an excess of dopamine in the brain is associated with positive symptoms of SZ

Question 3

what are schizophrenics thought to have high levels of?

Answer 3

D squared receptors on receiving neurons, resulting in more dopamine binding, and thus more neurons firing - causes hallucinations/delusions

Question 4

support for the dopamine hypothesis

Answer 4

‘Normal’ individuals exposed to large doses of dopamine releasing drugs such as amphetamines develop the characteristic symptoms of a schizophrenic episode.

Question 5

how are high levels of dopamine treated?

Answer 5

Antipsychotic drugs block the activity of dopamine in the brain, eliminating symptoms such as hallucinations and delusions.

Question 6

what is hyperdopaminergia linked to the subcortex?

Answer 6

High dopamine activity in subcortex (central areas of the brain) is associated with hallucinations and poverty of speech (e.g. excess of dopamine receptors in Broca’s area).

Question 7

what is hyperdopaminergia linked to the prefrontal cortex?

Answer 7

low levels of dopamine in the prefrontal cortex (responsible for thinking and decision-making).

Question 8

what is the revised dopamine hypothesis?

Answer 8

• Davis and Kahn (1991) proposed that positive symptoms are caused by an excess of dopamine in subcortical areas of the brain.
• Negative and cognitive symptoms arise from a deficit of dopamine in the prefrontal cortex.

Question 9

what are neural correlates?

Answer 9

Neural Correlates are measurements of the structure or function of the brain that correlate with an experience (i.e. the positive or negative symptoms of schizophrenia), usually studied using MRI and PET scanning techniques.

Question 10

how does the hippocampus link to schizophrenia?

Answer 10

deficits in the nerve connections between the hippocampus and the PFC correlate with the degree of working memory impairments, a cognitive impairment in schizophrenia (Mukai et al., 2015).

Question 11

SZ patients have been found to have enlarged ventricles in the brain - what does this mean?

Answer 11

• Researchers have found that many people with SZ, particularly those displaying negative symptoms, have enlarged ventricles (brain cavities filled with cerebrospinal fluid) (Hartberg et al., 2011).
• Enlarged ventricles are thought to be a consequence of nearby parts of the brain not developing properly or being damaged.
• Cannon et al. (2014) found that individuals at high clinical risk who developed SZ showed a steeper rate of grey matter loss and a greater rate of expansion of brain ventricles compared to those who did not develop SZ