Brain Lesion and fMRI Studies and the Myth of Cognitive Function Localization
There have been two basic assumptions long held in the traditional view of cognitive processing in the human brain: firstly, cognitive processes are exclusively functions of the cerebral cortex, and secondly, the cerebral cortex is divided into discrete areas of cognitive function. However, many observations and studies have incontrovertibly demonstrated that 1) so-called “cognitive processes” are not limited to specific areas of the brain nor reside exclusively within the cerebral cortex, but that many different areas of the brain contribute to cognitive functions, and that 2) cognitive functions in themselves are diffuse phenomena. To illustrate both points, a most obvious fact that contradicts the notion that specific “centers” of the brain, or specific regions of the brain are (either wholly or principally) responsible for specific so-called “cognitive functions,” is that acquired cognitive deficits attributed to an insult [i.e., a lesion resulting from a cerebrovascular accident (CVA), a tumor, a neurodegenerative process or an impact injury] to a particular area of the brain does not necessarily correspond to the area proposed as the “center” for the cognitive function affected. This paper closely examines what constitutes cognitive processes and what exactly can fMRI studies reveal about discrete cognitive functions of different areas of the brain.
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