A Comparative Study on Human Cerebrocortical Cytoarchitectonics; Effects of Aging and Brain Weight Increase on Cortices of Premotor area (Brodmann's area 6) and Precortical Gyrus (Brodmann's area 4) in Human Brain

Abstract

The cytoarchitectures and aging effects between summital cortex of the precentral gyrus(Brodmann's area 4) and caudal sulcal cortex of the premotor area(Brodmann's area 6; 6a) were compared in terms of comparative cytoarchitectonics in normal 418 cerebral hemispheres of 209 postnatal brains (115 of males' and 94 of females'). Statistical constancy of the relative total neuronal density in both cortices was noticed throughout the postnatal life span regardless of the aging and brain weight increase, except in 0-1 year old age group and 300-499 gm of brain weight group. An insinuating increment of relative total glial densities were shown according to successive increase of age, and the denser values in premotor cortex were noted than that of precentral gyrus in both sex and side. In adult, the relative total neuronal density was not directly affected by the cortical thickness and aging, but the relative total glial density was so affected by the cocrtical thickness, and aging, but not by brain weight.