Grounded Theory

There is clear evidence of localisation of function in the cerebral cortex. Discuss.

The Brain more than any other part of us, defines our individuality. It is the repository of our particular and unique memories, the controller of our defining skills and abilities, the facilitator of our interactions with our environment and our communications with our fellow human beings. Consequently damage to the brain is always serious.

The brain consists of billions of cells of numerous different types, the most important of which, form the point of view of overall brain function, are nerve cells and neurones. The brain is made up of two large, more or less symmetrical, cerebral hemispheres mounted on a central core of stalk of tissue, which is continuous with the spinal cord. The spinal cord is an intro connecting communication system through its nerve pathways, which connect with it, information can be relayed and collected to any point within the body. At its upper end of the spinal cord gives way to the medulla oblongata and can be seen as an extension of the spinal cord. Vertical communication is via ascending and descending nerve fibre tracts and horizontal communication via the cranial nerves.

Above the medulla are two remaining components of the hindbrain. The pons, which is situated on the ventral aspects of the brain, the pons carry messages from the higher parts of the brain to the spinal cord.

Returning to the outer covering of the cerebral hemisphere, The cerebral cortex. By virtue of its position, this is the part of the brain (especially the frontal and temporal cortex) most likely to be damaged in traumatic brain injury it is also the area of the brain most closely associated with higher cognitive function. In the human 80% of the brain consists of cerebral cortex.

The functions of the cerebral cortex can be divided into four separate areas or lobes, the four lobes, frontal, parietal, occipital and temporal. It is very difficult to produce a manageable overview in terms of discussing their functions. In part this is because none of the lobes can be regarded as a functionally coherent entity.

The frontal lobes are now known to have a super ordinate role in the planning, sequence and monitoring of a wide variety of behaviours. (Lund 1973) describes the frontal lobes as the 'executive of the brain' it contains the vital parts of the brains system for the control of movement and areas involved in language, memory and personality processes.

Within the parietal lobes is to be found the primary somatosensory cortex, which receives and analyses information from the skin including touch. Damage to this part of the brain can lead not only to impairment of specific aspects of somatosensory processes but also a distorted sense of its own body and its relationship to the immediate environment. However there is evidence for parietal involvement in many other functions as well, including constructional ability, attention and again aspect of language and memory.

The auditory cortex is to be found in this part of the brain known as the temporal lobes but some complex visual processing also takes place here. Finally like the frontal lobe appears to be involved in the regulation of personality including aspects of sexual and aggressive behaviour.

The cerebral lobes, which most closely approach functional coherence, are the occipital lobes. This part of the brain receives visual information already partially analysed by the retina and through a process of stages. In summary, whilst their is division of labour between the four cerebral lobes they operate in a highly complex, integrated and interactive way in mediating cognitive, behavioural function and recovery of functions following brain damage.

Within this brief description of the brain in the preceding section it is clearly implied that sensory, motor and cognitive functions are controlled to a very considerable extent by discrete areas of tissue within the brain. This doctrine of ' localisation of function' has been the framework of accumulated knowledge about the brain. However, the principle of localisation has not gone unquestioned. Certainly, over the years many scientific and clinical findings have come to light, which are different to reconcile with the view that psychologist and behavioural functions are completely localised within a specific area of brain tissue.

For example Phineas Gage had an accident in which an iron bar was blown through his head from his lower check to his forehead. Although he suffered a slight personality change it is not the impairment in Gage's personality but his apparent lack of impairment in terms of any other functions, which is remarkable.

John Lorber (1980) rejects the strict localisation of function view of the brain with his study on sufferers of hydrocephalus. Within a sample of 253 he found that 95% of those who suffered extreme hydrocephalus had either higher or normal IQ levels.

A third finding which appears not to fit the concept of ' localisation of functions' is that of language developments in children who have undergone left hemispherctomy, which is, were language is localised. Language would develop nevertheless (Vargha - Khadem and Polkey, 1992)

All of these apparently discrepant findings can be impaired in many respects if subjected