Brain Function - Lateralization and Localization .
Although a bilateral organ, the brain exhibits both structural and functional asymmetry (Hugdahl,2005). Apart from anatomical differences, major differences exist between the functions of the two cerebral hemispheres of the brain, with each hemisphere dominant for certain behaviors or functions. The specialization of functions in the hemispheres is known as cerebral lateralization. Observations indicate that the left hemisphere controls a set of abilities, such as linguistic processing and the right controls functions such as visuospatial abilities (Parker&Riley;,2010). Evidence of lateralization was confirmed by the effects of the left and right unilateral cerebral lesion in brain damaged patients. The effects vary accordingly with the hemispherical dominance and the functions affected (Kalat, 1999). .
Though the lateralization is discrete, the hemispheres do not operate independently but communicate constantly via the corpus callosum, a bundle of neural fibers which connects the two cerebrals, to execute a function. .
Whilst lateralization refers to the specialization of functions located in the respective hemispheres, localization refers to the specific areas in the brains that are responsible for specific functions; these areas can be in both hemispheres. It denotes that specific parts of the brains controlled specific cognitive functions, behavior and emotions (Parker & Riley,2010). Evidence of localized functioning is presented in the studies from neural imaging of brain functions during cognitive tasks. These imaging indicated that the operations that trigger the functions are strictly localized (Posner, Petersen, Fox & Raichle,1988).
Evidence for Lateralization of Language and Language Functions .
Observations indicating that patients with left brain damage invariably have more difficulty in language processing functions than those with right brain damage supported the evidence that language is a left hemispherical dominated function (Aitchison,2008).
