The aim of the research is to ascertain whether asymmetry in the gross morphology of the right and left temporal lobes in the human brain is related to functional asymmetry. Asymmetry has been documented in the planum temporale - the posterior part of the superior surface of the temporal lobe. Specifically, the research aims to establish whether the more prevalent pattern of a larger left planum is a substrate of left-hemisphere representation of language functions. To do this, seriously ill cancer patients are recruited who are willing to take an extensive battery of neuropsychological tests and to consent to a postmortem examination in the event of death.
The aim i s to study 60 cases with both psychological and anatomical measures. Measures of the planum temporal will be studied in relation to the test scores, as will other anatomical measures, including Broca's region and the corpus callosum. The purpose of the research is also to study whether there are any neurohistological differences between the hemispheres that could be a basis of functional asymmetry. At least 16 specimens will be studied in one particular cytoarchitectonic region of the planum; the cases will be selected to vary in planum asymmetry, sex and hand preference. Cortical thickness and various cell counts will be obtained from Nissl-stained sections. The histological measures will be compared with the gross morphology and psychological scores. Histological analysis will also be done in Broca's region and the corpus callosum. The work involves the disciplines of cognitive neuropsychology and neuroanatomy, as well as extensive organization to coordinate the efforts of various groups, including oncologists, hospital staff, community physicians, pathologists and research staff. It is anticipated that this research will contribute theoretically to the biological basis of cerebral dominance and to the neural mechanisms of cognition. It may have relevance to the study of individual differences in cognition and brain organization, to the variation in the cognitive deficits and recovery subsequent to brain damage, and to etiological factors in some neuropsychiatric disorders that may involve atypical patterns of functional asymmetry. Finally, the method of this research may serve as a prototype for the study of other brain-behavior issues in normal and disordered populations requiring testing before and after death.
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