Identity And Universals: A Conceptualist Approach to Logical, Metaphysical, and Epistemological Problems of Contemporary Identity Theory
Appendix A, Brain Regions and Their Functions
by Carolyn Ray
Date: 11 Nov 98
Copyright: Carolyn Ray
Although the functions of the brain are integrated in such a way as to require the cooperation of all parts, damage to certain parts does result in somewhat specific impairment. The picture of the right-handed person, for example, is often painted with one active hemisphere and another negligible one, and from there the conclusion is drawn that the negligible one may be removed without much ill effect. On the contrary, the removal of a hemisphere would involve not only the removal of certain more or less specific capacities, but would also result in the severe impairment of the functions that are centered in and mainly performed by the remaining hemisphere. The partial list of known localizations should make it clear that the project of simple removal of one hemisphere or the other would result in an entity very different from a normal human being.
Cerebral Cortex: The outer layer of the cerebrum, where most personality traits seem to be localized.
The Cerebral Hemispheres: Two hemispheres can be distinguished in the cerebrum; these hemispheres physically correspond to differentiated functions of the nervous system. The differentiation is not perfect and complete, but there are many pronounced differences between the cerebral hemispheres. Some are listed below.
Memory for shapes
Limited language comprehension (words are only understood in full context)--but this hemisphere is, i.e., unable to express the information being processed there in words in any way: it is incapable of speech, writing, or even pointing to an object whose name rhymes with the name of an object seen.
Superior recognition of topological forms, faces
Superior recognition of emotions
Left visual field
Superior assimilation of wholes
Hearing of speech
Superior comprehension of language
Right visual field
(Information in the section above adapted from Trevarthen, "Split-Brain and the Mind")
Not all of the aspects of persons or of personality are strictly associated with the cerebral cortex, let alone with one hemisphere or the other. Here is a brief list of the major functions known to be associated to varying degrees with subcortical regions.
Basal ganglia: regulates the body's movements.
Cerebellum: coordinates complex movements of the body, especially the limbs. May act as automatic pilot when performing learned functions (driving, playing an instrument, brushing teeth) may influence emotional development. Main functions include getting data from muscles, joints, tendons and inner ear and adjusting posture and coordinating muscular movements accordingly.
Hypothalamus: coordinates the central nervous system; plays a crucial part in our emotions, controls basic life processes, and regulates metabolism, temperature, production and circulation of hormones, states of being awake or asleep, aggression and timidity, mating and sexual behavior, sympathetic and parasympathetic nervous systems.
Limbic system: (of which olfactory lobes are part) controls emotions, behavior, learning and short-term memory.
Mammillary Bodies: small protrusion of the bottom of the bottom of the brain at the posterior end of the hypothalamus, implicated in the version of Korsakov's Syndrome suffered by Jimmie G, whose brain was apparently otherwise normal but who exhibited total anterograde amnesia.
Thalamus: relays information from sense to cerebrum; relays signals from cerebrum to muscles.
(Information in the section above adapted from Peter W. Nathan's "Nervous System")
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