Further neural correlates of schizophrenia Flashcards
Enlarged ventricles?
People with schizophrenia have abnormally large ventricles in the brain.
( Ventricles are cerebrospinal fluid filled cavities)
- This means brains of schizophrenics are lighter than normal and hence the grey matter volume shrinks in SZ patients as ventricles enlarge.
This could be a consequence of nearby parts of the brain not developing properly or being damaged – this links to active loss of grey matter in early stages of SCH which is consistent with onset of SCH in late teens /early 20’s
This loss of grey matter leads to cognitive decline linked to NEGATIVE SYMPTOMS
Hypofrontality?
Hypofrontality is a state of decreased cerebral blood flow (CBF) in the prefrontal cortex of the brain.
This means an underactivation of the dorsolateral prefrontal cortex, particularly on cognitive activation linked to negative symptoms- tested by using the WISCONSIN CARD SORT .
Those with SZ have difficulty in tasks requiring
executive memory functions.
Hippocampul-amygdala region?
Schizophrenia patients have smaller volume in bilateral amygdala and hippocampus compared with healthy controls. The reduction in the volume of the amygdala was found in patients with early onset SZ. When the relationship between volumes & symptoms indicates that the left hippocampus-amygdala was found to have a negative correlation with thought disorders & negative symptoms.
Significant negative correlations were found between:
(i) Lower volume of left amygdala & thought disorder
(ii) Lower volume of left hippocampus & negative symptoms
(iii) Lower left anterior & posterior hippocampus volumes with positive & negative symptoms.
This supports the role of the hippocampus-amygdala in schizophrenia. When researchers scan the frontal lobes of those with schizophrenia, they discover that there is a large decrease in neural waves in this brain area, which means there is less synchronised neural firing or communication. The disruption of neural network communication is a contributor to symptoms of schizophrenia.
NEURAL CORRELATES - Research evidence?
McEwan argues that nurturing influences could actually instigate these structural changes in the brain, making the explanation incomplete. Children and adolescent brains are far more sensitive to chronic stressors. This can reshape the structure and organisation of cortical regions, contributing to SZ and adding credibility.
NEURAL CORRELATES - Cause and effect?
There is clearly a relationship between the two, but we cannot conclusively state whether the brain abnormalities caused SZ or if SZ caused the brain abnormalities. This could suggest that anatomical differences within the brain are merely correlational and of limited use.
NEURAL CORRELATES - Methodological problems?
Biologically reductionist as it is reduced to the neural level of explanation, as it states that differences in the brain is the sole cause of SZ. Ignores other factors such as the interaction with the environment and the role of excessive drug and alcohol use. This means that the explanation may be too simplistic
NEURAL CORRELATES - Validity?
Enlarged ventricles are not exclusive to SZ - they may occur in the brains of those that suffer from Parkinson’s disease and other disorders. Not all patients have enlarged ventricles, and others who have enlarged ventricles sometimes never experience SZ. Therefore the explanation is less valid, and we cannot be sure that this is a leading factor.
NEURAL CORRELATES - Scientific?
Brain structure can be studied in a controlled, objective and falsifiable manner. For instance, we can study the brain structures of SZ patients using MRI scans to be able to identify large ventricles. Means that psychology is viewed as a scientific discipline so the explanation is more credible.
