Lesson 8 - The Biological Approach Flashcards
The CNS
Consists of the brain and spinal cord
The PNS
Sends and receives messages from the CNS to other parts of the body
The Brain
Made up of two hemispheres and has 4 lobes
Parietal lobe
Sensations, reacting with the environment
Frontal lobe
Executive function, emotional control
Temporal lobe
Deals with language and learning
Occipital lobe
Primarily deals with vision
Strengths of biological structures
Relies on brain scans such as PET and MRI scans and postmortems. This adds to the very scientific and objective approach
Weaknesses of biological structures
- The idea of brain structure is more applicable at explaining some behaviours but not others, for example it can explain how infection and the anatomy of the brain can influence schizophrenia, but phobias are generally learned
- We do not know 100% about the brain. More investigation is needed in identifying which part of the brain is responsible for certain behaviours
- Can we be sure that brain malfunctions are a cause of behaviour or the other way around?
Swayze
- Reviewed 50 studies of schizophrenic patients and examined them using MRI’s
- From these images, the brain structure could be examined and it was found that their were structural abnormalities:
- Decrease in brain weight
- Enlarged ventricles filled with water
- Smaller hypothalamus
- Less grey matter
These are the neural correlates of schizophrenia, meaning that they are the brain activities that are associated and are required for schizophrenia to be manifested
Strengths of Swayze
Torrey conducted a meta analysis of 65 studies and found significant abnormalities in brain structure in schizophrenic patients compared to a control. The patients recieved no antipsychotic medication, therefore he concluded that this was not a side effect, but a correlate of schizophrenia.
The use of MRIs are also very scientific and provide an objective image of brain structure
Weaknesses of Swayze
- Andreason (1982) criticised the explanation of schizophrenia using neural correlates. He found that the extent to which enlarged ventricles in the brain are linked to schizophrenic patients is insignificant and that there is very little difference between the neural correlates between a schizophrenic and healthy person
- Cause and effect is unclear. Are neural correlates developed first which triggers a behaviour? Or is an illness like schizophrenia developed first and then neural correlates after?
- Davidson and Neale (2001) found that enlarged ventricles cannot alone cause schizophrenia, because similar correlates are found in patients with mania. It could be a vulnerability factor which makes getting the illness more likely
Neurotransmitters
Brain chemicals that communicate information throughout our brain and body. They relay signals between nerve cells, called neurons’
In the brain, it occurs via cerebral fluid
Hormones
Produced by the endocrine system
Consists of ductless glands that release these chemicals into the body which effect behaviour
Strengths of neurochemistry
- Neurotransmitters can be measured scientifically which increases is objectivity. For example, we can measure the amount of dopamine by injecting a needle into the spine and extracting spinal plasma fluid
- We know that a lack or excess of a particular neurotransmitter has an effect on behaviour, like low serotonin can cause depression and we can then find treatments for this, like SSRIs.
Weaknesses of neurochemistry
- Cause and effect needs to be established. How can we be sure that changes in neurotransmitter levels causes a behaviour or if a behaviour causes these changes instead?
- Can be viewed as reductionist. It ignores other explanations and it may be hard to think that a mental illness is solely caused by chemical imbalances
- Can be criticised by the cognitive approach, which argues that negative internal thought patterns rather than chemical imbalances cause mental illnesses like depression.
‘The Dopamine Hypothesis’ by Davis and Neale
- Patients with schizophrenia tend to have high levels of dopamine
- Drugs such as phenothiazines block the dopamine in the brain, and the positive symptoms (experiences that are ‘added on’ to a person) such as hallucinations and delusions seem to reduce
- A drug called L-Dopa increases the dopamine levels in the brain. It can induce schizophrenic-like symptoms and it has been tested on healthy non-psychotic people
- Drugs such as LSD and amphetamines do the same thing
Strengths of the Dopamine Hypothesis
- Randrup and Munkvad (1966) found that when injecting amphetamines into rats (which increase dopamine levels in the brain) this led to symptoms consistent with that of schizophrenia.
- There are a lot of scientific and objective brain scanning evidence that support this hypothesis, such as PET and fMRI scans
- Led to the development of typical and atypical antipsychotics
Weaknesses of the Dopamine Hypothesis
- Cause and effect is unclear, does high levels of dopamine cause schizophrenia or does schizophrenia cause a high level of dopamine
- Dopamine may be associated with many mental illnesses such as mania as well as schizophrenia, and mania is not effectively treated with phenothiazines.
- It is a reductionist idea, as it reduces the complicated phenomenon is schizophrenia to a single component
