Biological explation for Schizophrenia : Neural Correlates Flashcards
Neural Correlates
Measurments of the strucutre of the brain that correlate with an experiences, in this case schizophrenia.
Neural correlates of negative symptoms
Avolution = loss of motivation
- Motivation involves anticipation of reward and certain regions of the brain, including the ventral straium, are believed to be particulary involved in this anticipation
Neural correlates of negative symptoms
Juckle (2006) - Negative correlation between levels of activity + negative symptoms
Found lower leveel of activity compared to a control group in the ventral straitum of schizophrenic paitents compared to controls.
Neural correlates of positive symptoms
Allen et al (2007) found lower activation levels in their superior temporal gyrus and the anterior cingulate gyrus in those experirncing auditory hallucinations.
Anterior cingulate cortex (ACC)
The frontal part of the cingulate cortex. It is also involved in certain high-level functions, such as reward anticipation, decision-making impulse control,and emotion
Ventral striatum
The front part of the striatum, which is a major portion of the basal ganglia and functions as part of the reward system
The superior temporal gyrus
Involved in the perception of emotions in facial stimuli. Furthermore,
- an essential structure involved in auditory processing, as well as in the function of language in individuals who may have an impaired vocabulary, or are developing a sense of language.
Neural Correlates - The Prefrontal Cortex
- Involved in executive control
- Research has shown that this impaired in sz paitents (Weinberger and Gallhofer, 1997)
Neural correlates - The hippocampus
- Several studies have reported changes in the hippocampus in SZ paitents
(Conrad et al.,1991). - Deficits in the nerve connections memory
Neural correlates - The hippocampus(Mukai et al.2015)
Deficits in the nerve connections memory impairments a central cogitve impairemny in SZ
Goto and Grace (2008) Neural correlates - The hippocampus
Suggest that hippocampal dysfunction might influence level of dopamine release in the basal ganlia, indirectly affecting the processing of information in the prefrontal cortex.
Neural correlates - Grey Matter
- Individuals with SZ have a reduced volume of grey matter.
- Researcher have also found that many people have SZ, particulary those
displaying negative symptoms have enlarged ventricles. (Hartberg et al. 2011)
Cannon et al. (2014)
Found that individuals at high clinical risk who converted to SZ showed a steeper rate of grey matter loss and greater rate of expansion of brain ventricles compared to those who did not convert to SZ.
Neural correlates - White Matter
Found in the brain and spinal cord and is made up of nerve fibres covered in myelin.
Du et al. 2013 Neural correlates - White Matter
Found reduced myelination of white matter pathways in SZ paitents, compared to healthy controls.
AO3 Neural correlates - Support for the influence of grey matter deficits
Vita et al. (2012)
Analysed the results of 19 stufies. Paitents with schziophrenia, compared with healthy controls, showed higher reudction is cortical grey matter over time.
- Pattern of grey matter reduction was specific to discrete cortical areas in frontal, temporal and partial lobes.
Link sentence Grey deficits AO3 Neural correlates - Support for the influence of grey matter deficits
Vita et al. (2012)
The loss of grey matter was especially active in the first stage of the disease consistent with the relatively early onset of SZ.
Challenges to dopamine hypothesis - Noll (2009)
Argues that antipsychotic drugs do not alleviate hallucinations and delusions in about 1/3 of people experiencing these symptoms.
Challenges to dopamine hypothesis - Noll (2009) - Link sentence
dopamine being the sole of postive symptoms other neurotransmitter systems, acting independently of the dopaminergic system, may also roduce the + symptoms associated with SZ
The dopamine hypothesis: Evidence from treatment (Support)
Leucht et al. (2013)
Carried out a meta analysis of 212 studies. They conducted that all the antipsychotic drug tested in these studies were significantly more effective than placebo in the treatment of + symptoms, acheieved by reducing the effects of dopamine.
Challenges to dopamine hypothesis - Noll (2009) - Link sentence
Findings also challenge the classfication of antipsychotic into typical and atypica groupings as differences in their effectiveness were only small.
Genetic Factors - AO1
Familiy studies
Have established that schizophrenia is more common among biological relatices of a person with SZ.
Twin studies
If MZ twins are more concordant than DZ twins this suggests that the greater similary is due to genetic factors.
Joeseph 2004
MZ - 40.4%, DZ = 7.4%
Adoption studies
As of the difficulties disentagling genetic and enviromental influences for individuals who share genes and enviroment, studies of genetically related individuals who have ben reared apart are used.
Adoption studies Tienari et al. 2000
Of 164 adoptees whose other had been diagnosed with SZ.
- 6.7% also recieved a diagnosis compared to only 2% of controls.
AO3 Adoption studies
Joeseph (2004) MZ Twins
AO3
Twin studies assume that the enviroment of MZ and DZ are equivalent.
- it is widley accepted that MZ twins are treated more similairy.
AO3 Adoption studies
Joeseph (2004) MZ Twins
AO3
Importance of this
It allows us to see that there is great similarity in genetic factor and concordance rate of MZ twins could be more similar enviroment rather than genetic factors
More specific genetic explanation
Point = SZ is a polygenetic - it requires a number of factors work in combination.
Explain = As there is no ‘SZ gene’ but severa; this increases an individuals overal vulnerability to developing SZ.
Evidence = Ripke et al (2014)
Ripke et al. (2014)
Carried out a huge study combinding all previous data from genome-wide studies.
- The genetic make-up of 37,000 paitents was compared to that on 112,00 controls
- 108 separate genetic variations were associated with increased risk of SZ.
The Dopamine Hypothesis - Support
Curran et al 2004
Amphetamines that increase the levels of dopamine make SZ worse and can produce SZ like symptoms in non-suffers.
The Dopamine Hypothesis - Support
Leucht et al 2013
- Carried out a meta-analysis of 212 studies
- Analysed the effectiveness of different antipsychotic drugs compared to placebo
- Findings = That all drugs tested were significantly more effective than placebo in the treatment of +ve and -ve symptoms
