L8 - The Biological Approach - The Influence Of Biological Structures & Neurochemistry On Behaviour Flashcards
Biological structures include
- Neurons & the nervous system
- the brain
Neurons & the nervous system
- CNS - brain & spinal chord - controls breathing & heart rate
- PNS - sends & receives messages from CNS to other parts of the body
- neurons transmit nerve impulses in form of electrical signals
The brain
- made up of left & right hemisphere
- has 4 lobes:
- parietal lobe - sensation - deals with & reacts to the environment
- frontal lobe - executive function - controls emotions
- temporal lobe - memory, language & hearing
- occipital lobe - primarily vision
Evaluation of biological structures
strengths
- brain scans
- scientific & objective
weaknesses
- explains some causes
- cause & effect
- more investigation
Brain scans
The biological model has its strengths in that the study of the brain relies on the use of scans, such as PET (Positron Emission Tomography) and MRI (Magnetic Resonance Imaging) and post mortem studies which adds to scientific evidence than can help support the biological approach. It can be viewed as one of the most scientific models/approaches
Some causes
The biological model can be criticised because it is more applicable at explaining the causes of some behaviours, but not others. For instance infection or neuroanatomy of the brain can cause schizophrenia, but there are some behaviours that cannot be well explained by these ideas. For instance the development of phobias is usually learnt
Cause & effect
Cause and effect is a disadvantage when looking at biological structures and their effect on behaviour. For instance can psychologists be sure that a brain malfunction is causing a behaviour to occur, e.g. a smaller hypothalamus causing schizophrenia?
More investigation
A problem of studying the brain is that psychologists still do not know 100% about the brain and its functions. Therefore there could be problems of trying to identify which part of the brain is responsible for certain behaviours and more investigation might be needed.
Scientific & objective
An advantage of looking at brain structures is they can be scientifically and objectively investigated in order to test how they might affect behaviour. For instance the brain can be investigated using FMRI and PET scanning which gives psychologists access to investigating and understanding how the brain functions
Brain structure
- neural correlates:
- Schizophrenia might develop due to structural and functional brain abnormalities.
Postmortems were used to investigate the structure of the brain in patients who had schizophrenia, but we now use MRI (Functional Magnetic Resonance Imaging) - study by Swayze
Swayze
- Swayze reviewed 50 studies of schizophrenic patients and examined their brain imaging using MRI (Magnetic Resonance Imaging).
- from brain images, the structure of brain could be examined & it was found that schizophrenic patients have structural abnormalities in brain including:
- A decrease in brain weight
- Enlarged ventricles (that are filled with water)
- A smaller hypothalamus
- Less grey matter (this is where the intelligence is held and it seems to have deteriorated)
- Structural abnormalities in the pre frontal cortex (where the personality is held)
Evaluation of Swayze
strength/weakness
- supporting evidence
weaknesses
- contradictory evidence
- cause & effect
- criticism
Criticism
Andreason (1982) has criticised the neural correlates explanation for schizophrenia. He found that the extent to which the ventricles in the brain are enlarged in schizophrenic patients is not significant; and therefore there is actually very little difference between the neural correlates of schizophrenic patients’ and normal people.
Cause & effect
Cause and effect needs to be established. Is it the fact that abnormal neural correlates actually causes schizophrenia to occur, or does schizophrenia occur first (due to other factors) and then cause the brain structure/neural correlates to alter
Supporting evidence
There is a strong amount of supporting psychological evidence to state that schizophrenia is caused by neural correlates changing in the brain that occur during pre-natal development in the womb. However, this does not explain why schizophrenia occurs in early adulthood (and not straight away during infancy)
Contradictory evidence
Davison and Neale (2001) have found contradictory evidence to suggest that enlarged brain ventricles are not only found in schizophrenia patients, but that sufferers of mania also have enlarged ventricles. Therefore enlarged ventricles alone cannot cause schizophrenia, but it could be a vulnerability factor that increases the risk of getting the illness.
Neurotransmitters
- This looks at the biochemistry of the central nervous system which involves hormones and neurotransmitters
- Hormones such as testosterone travel in the blood stream
- Neurotransmitters defined as, “Brain chemicals that communicate information throughout our brain and body. They relay signals between nerve cells, called neurons”
- In the brain the transmission of chemicals - (neurotransmitters) occurs via cerebral fluid, for instance high levels of dopamine cause schizophrenia
Hormones
- The endocrine system is responsible for producing hormones in the body, for instance high levels of testosterone might increase aggression levels.
- The endocrine system consists of ductless glands that release hormones into the body which will affect behaviour
Neurochemistry evaluation
strengths
- objective & scientific
- can now treat
weaknesses
- cause & effect
- reductionist
- criticised by cognitive approach
Objective & scientific
Neurotransmitters can be measured objectively and scientifically which is a strength. For instance dopamine can be measured by inserting a needle in the spine and extracting spinal plasma fluid. This means we can obtain objective and scientific measurements
Cause & effect
A negative point of neurochemistry is that cause and effect needs to be established. Can we be sure that high/low levels of neurotransmitters actually cause a change in behaviour, e.g. low levels of serotonin cause depression
Can solve issue
A strength of neurotransmitters is that if we know that a lack/excess of a particular neurotransmitter has an effect on behaviour e.g. low levels of serotonin cause depression, then we can look for relevant treatments that can help solve the issue. For instance giving depressed people SSRI drugs that increase serotonin
Reductionist
Neurotransmitters can be viewed as reductionist which can be a disadvantage. To say that complex human behaviour can be affected by neurotransmitters alone is too simplistic and inaccurate, for instance is depression really just caused by low serotonin levels
Cognitive approach
The idea that neurotransmitters can have an effect on behaviour can be criticised by the cognitive approach.
The cognitive approach would state that behaviour is caused by thought patterns and thinking rather than neurochemistry or chemicals, for instance depression could be caused by negative thinking according to the cognitive approach rather than by low levels of serotonin (biological approach)
Dopamine hypothesis by Davis & Neale
- Schizophrenic patients’ tend to have high levels of the neurotransmitter dopamine in their brain
- When drugs such as phenothiazines are given to patients’ that block dopamine in the brain; the positive symptoms of schizophrenia seem to reduce (hallucinations and delusions)
- This drug can induce symptoms of schizophrenia, and it has been tested on healthy non psychotic people induce schizophrenic symptoms.
- Dopamine metabolism in schizophrenic patients’ seems to be abnormal,
Evaluation of dopamine hypothesis
strengths
- research support
- scientific & objective
weaknesses
- cause & effect
- not just schizophrenia
- reductionist
Research support
There is a great deal of research to support the hypothesis that schizophrenic patients have a high level of dopamine in their brain. For instance research by Davidson found that when schizophrenic patients were given the drug L-Dopa their schizophrenic symptoms got worse and intensified.
Cause & effect
Cause and effect is not clear. Could it be that an increase in dopamine causes schizophrenia to develop; or could it be that the illness develops first (due to another cause) and then this causes dopamine levels to increase?
Not just associated with schizophrenia
Dopamine is a neurotransmitter that is not only associated with the illness of schizophrenia. Dopamine has also been associated with mania (bipolar depression), and this illness is not alleviated by phenothiazine drugs. Therefore is seems that dopamine has a complex role in the brain and might be associated with many psychological illnesses and not schizophrenia alone.
Reductionist
The dopamine hypothesis could be viewed as being reductionist. It looks at the complicated phenomenon of the causes of schizophrenia and reduces it down to the component of dopamine alone.
Scientific & objective
There is a great deal of scientific evidence and support for the dopamine hypothesis as a cause of schizophrenia. Most of the research has used evidence that have come from brain scans (PET and fMRI) which is highly valid and reliable information. This gives scientific and objective data
