Biological Model of Abnormality

Biological Model

The biological model of abnormality makes the assumption that psychological and behavioral abnormalities have biological causes. In other words things go wrong with behaviour because something has gone wrong with brain.

Possible causes of abnormal behaviour

§  Abnormality can be inherited. Biological dysfunctions, such as changes in neurotransmitter levels, increased levels of certain hormones, or the dysfunction of certain neurons in the brain, can cause abnormal thinking, behaviour and emotions. 
Biochemistry
Abnormal functioning of the brain can be caused by abnormal levels of neurotransmitters and hormones. Neurotransmitters are the chemical messengers that allow neurons to communicate with one another at synapses (the gap between the end terminal of one neuron and the membrane of the dendrites or cell body of the next). Neurotransmitters that have been implicated in abnormal functioning include:
Serotonin. Low levels of serotonin are linked to depression, anxiety and obsessive compulsive disorder.

§  Dopamine. Parkinson's disease is caused by the death of dopamine producing cells in the substantia nigra. Addiction is linked to the reward pathways that use dopamine as a neurotransmitter.

Hormonal Imbalance

§  Hormones are chemical messengers that are secreted into the bloodstream by glands and control various body functions including some nervous system functions. Hormones implicated in abnormal functioning include:

§  Cortisol. Chronic stress involves high levels of cortisol being produced by the adrenal cortex.

§  Insulin. Diabetes mellitus is caused by the inability of cells in the pancreas to produce insulin.
Structural damage or abnormality
Damage to certain areas of the brain, for example as the result of a head injury, stroke or brain surgery, or a failure of brain areas to develop properly can lead to abnormal behaviour:
Damage to the hippocampus, as seen in the cases of  HM and Clive wearing can lead to profound memory loss.

Damage to Broca's area of the left temporal lobe may lead to the inability to understand speech properly. Patients with schizophrenia have abnormally large ventricles in their brains.

Lobes of the cerebrum Cortex

The Cerebrum: The cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes": the frontal lobe, parietal lobe, occipital lobe, and     temporal lobe.

What do each of these lobes do?

§  Frontal Lobe- associated with reasoning, planning,  parts of speech, movement, emotions, and problem  solving

§  Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli

§  Occipital Lobe- associated with visual processing

§  Temporal Lobe- associated with perception and recognition of auditory stimuli, memory, and speech

          Damage of these lobes Causes many disorders

e.g.  An example of this can be from an accident, which can cause damage to the orbitofrontal cortex area of the brain. It leads to Alzheimer disease, Frontotemporal dementia and Pick's disease