Biological: Neural Correlates

Question 1

What are neural correlates?

Answer 1

-Measurements of the structure and function of the brain that correlate with an experience.
-An explanation based on assumption that abnormalities within specific brain areas may be associated with development of schizophrenia.
-Originally evidence limited to post-mortems, now uses non-invasive scanning techniques e.g. fMRI, so functioning of brain can be compared to non-sufferers to identify brain areas that may be linked to schizophrenia - best achieved by giving tasks to perform associate with types of functioning known to be abnormal in schizophrenics.

Question 2

Explain neural correlates of negative symptoms in the ventral striatum and avolition

Answer 2

-Loss of motivation, which involves anticipation of reward, certain regions of the brain e.g. ventral striatum, believed to be particularly involved in anticipation.
-Juckel et a (2006) measured activity levels in ventral striatum in schizophrenia and found lower levels of activity than those in control group.
-Found negative correlation between activity levels in ventral striatum and severity of overall symptoms.

Question 3

Explain neural correlates of positive symptoms in the occipital lobe and visual hallucinations

Answer 3

-Jibiki et al (1991) showed activity in this area is disrupted in schizophrenic patients, leading to incorrect processing of visual stimuli.
-These visual misperceptions or errors don’t always involve hallucinations but can result in improper interpretation of things like facial + emotional expressions an gestures etc.

Question 4

Explain neural correlates of positive symptoms in the temporoparietal junction + auditory hallucinations

Answer 4

-We have 2 separate speech recognition systems - ‘what’ determines content of speech + ‘where’ distinguishes internal speech and external speech.
-Plaze (2011) suggested disruption to ‘where’ system could lead to a person perceiving their own internal speech as coming from an external source, experienced as an auditory hallucination.

Question 5

What are 2 strengths of the neural correlates explanation?

Answer 5

Objectivity:
-Imaging techniques have rapidly enhanced knowledge of brain, MRI technique involves using radio waves and magnetic fields to construct a 3D image of region being scanned.
-Better than X-Ray as quality is better, for a complex disorder like schizophrenia it has an advantage as it is non-invasive and used on humans.
-Before was left to animal studies or post-mortem. Schizophrenia has a young age onset and doesn’t kill, so time difference between developing and death renders this examination useless.
Use of these techniques vital in advancing knowledge, they are valid and reliable, helping us to provide factual, scientific evidence.

Evidence supporting link between TPJ and auditory hallucinations:
-Plaze used MRI scans of 45 patients and 20 controls, split into 2 groups - those who heard hallucinations internally and those externally.
-Found differences in MRI images of TPJ, a decrease in white matter for those who heard externally ad an increase in white matter for those who heard internally.
It would appear the way the TPJ develops determines whether hallucinations are perceived as originating from inside or outside the person’s own body.

Question 6

What is 1 limitation the neural correlates explanation?

Answer 6

Problems with cause + effect:
-Question whether brain dysfunction caused the schizophrenia or whether schizophrenia caused the brain dysfunction.
-e.g. correlation between levels of activity in ventral striatum and negative symptoms - may be something wrong in striatum causing symptoms, or symptoms mean less info can pass through striatum resulting in reduced activity.
-Study of brain plasticity has taught us the brain can change in shape, size + function depending on how much stimulation it receives.
Therefore it’s almost impossible to ascertain whether the faulty brain components have caused schizophrenia or it has caused the faultiness.