Localisation of function means that different areas of the brain are associated with particular physical and psychological functions. Lateralisation of function refers to the dominance of one hemisphere (side) of the brain for particular physical and psychological functions. Left brain functions, include: analytic thought, logic, language, science and maths. Right brain functions include: holistic thought, intuition, creativity, art and music.
The human brain is made up of three concentric layers: The central core which regulates our most primitive and involuntary behaviours. The limbic system which controls our emotions and the cerebrum or cortex which regulates our higher mental processes
Different functions are located in different areas of the cerebrum:
· The frontal lobe is the location of our awareness or consciousness.
· The occipital lobe is where vision is located
· The temporal lobe is the location of auditory processing and memory
· The Parietal lobe is the location for sensory and motor movements. It also contains the motor area which is responsible for our voluntary movements and the somatosensory area which responds to heat, touch, pain etc.
Localisation of language
Broca’s area to the left of the frontal lobe, governs speech production. Damage to Broca’s area causes speech to be slow and laborious. Wernicke’s area in the left temporal lobe governs the understanding of speech. Damage to this area causes comprehension problems and the person’s speech is fluent but meaningless. Studies using information from brain scans show that either Broca’s area or Wenicke’s area is active when people perform different types of language task. For example, listening to nouns involves Wernicke’s area, and thinking of what verbs go in a phrase uses Broca’s area.
· Although some functions can be located in certain areas of the brain, most functions involve many inter-connected areas – in other words brain function is holistic not localised
· People with brain damage to a specific area of the brain (e.g. following a stroke) often recover function over time because another area of the brain takes over. This is referred to as brain plasticity.
Methods used to identify cortical specialisation
Neurosurgery is an invasive method of investigating cortical specialisation as it involves manipulating structures within the brain. There are two main ways of doing this. Ablations: a surgical procedure to remove areas of the brain and lesions: a surgical procedure used to cut neural connections in the brain. Occasionally there are psychological effects following brain operations. EG:…