Hemispheric Lateralisation

The human brain is split into two cerebral hemispheres, connected by the corpus callosum. Broad generalisations are often made about each hemisphere having characteristic labels. The left side is often thought to deal with language production and comprehension and generally be more rational and analytic. The right hemisphere on the other hand is often labelled as creative, emotional and intuitive. Underlying these labels is the idea that each hemisphere is thought to be qualitatively and quantitatively different, with one hemisphere being more dominant in a particular characteristic than the other hemisphere. This is supported by evidence from a number of different studies involving research on language, visuo spatial abilities, and split brain patients. Split brain patients are people who have under gone a particular type of surgery in order to try and rid epileptic seizures. The surgery involves severing the corpus callosum in order to destroy the path of the epileptic seizure. The result of this surgery is that the two hemispheres are unable to interact because all connections have been broken and therefore the two hemispheres act as two separate brains. This finding suggests that the two hemispheres are independent of one another.
The research on language has most commonly been tested by using neuroimaging techniques such as Functional Magnetic Resonance Imaging (fMRI) scans which measure the flow of blood within the brain, the faster the flow of blood, the more oxygen that is being used and therefore the more energy the brain is using. This scan helps us to see which areas of the brain are active when different tasks are completed and thus helps us to localise brain function. When studying language participants are given tasks such as recognising words or may be asked to speak or read a few sentences, therefore allowing us to see where these functions take place, in most patients language tasks are found to activate areas within the left hemisphere. Occasionally some people are found to have activation in the right hemisphere but this is much rarer .