Localisation of function

• Localisation of Function: the theory that regions of the brain are ​responsible for specific functions.
• The main parts of the brain include the motor cortex, somatosensory cortex, the visual and auditopry centres and the speech centres.
• The motor cortex is responsible for fine voluntary motor movements and is located in the frontal lobe of the brain. The lobes of the brain function contralaterally, so the motor cortex on the right hemisphere controls the left side of the body.
• The somatosensory cortex is responsible for detecting and processing stimuli in the environment through the senses. It is located in the parietal lobe of the brain and is present in both hemispheres.
• The visual centre is located in the visual cortex and is responsible for processing visual information. The right hemisphere processes visual information of the left visual field.
• The auditory centre is located in the temporal lobe of the brain. It is responsible mainly for processing sounds and auditory information. This includes the duration and intensity of a sound.
• Broca’s area: involved in speech production. It is located in the left frontal lobe of the brain and was discovered by Broca’s investigation of a patient called ’Tan’ who could understand speech but not produce it.
• Wernicke’s area: responsible for speech comprehension. It is located in the left temporal lobe and close to the regions of the brain involved in auditory and visual input.
• Limitation of localised function - not all behaviour is localised.

  -Lashley suggests that basic sensory and motor functions may be localised, but higher mental processes are not.

  -Intact areas of the cortex can take over specificn brain functions following trauma, as such it is not the location but the extent of damage that creates an impact.

  -Supported by the idea of plasticity & functional recovery.
• Limitation of localised function - a reductionist approach.

  -Research suggests that the importance of neural function lies not in one brain area but the complex interaction of many.

  -Although different regions have their own functions, they must work together interdependently (Wernicke).

  -Complex behaviours are built up gradually as a stimulus enters the brain and move through structures for processing. Any damage to a connection results in neural impairments.
• Strength of localised function - support for language areas.

  + Support for Broca and Wernicke’s areas is derived from the damage to the areas in the brain.

  + Broca’s aphasia arises when an individual is unable to produce speech, and Wernicke’s aphasia is when a patient cannot understand speech.

  + Demonstrates the importance of the role of these areas in speech.