Volumes of Basal Ganglia and Cortex in Mammals

Abstract

A resurgence of interest in the basal ganglia has accompanied the recent excellent studies on these nuclei. 1 It is perhaps surprising, therefore, that the comparative morphology of the striatum and the pallidum has received so little attention. The present report presents data on the absolute volumes of these areas in a closely graded series of primates and in one sub-primate brain. Because of the linking of the basal ganglia with the cortex and the general problem of the relationship of brain size to development, the volumes of the cortex and the brain have been included in this study.

The method followed is that suggested by Dornfeld, Slater and Scheffe, 2 wherein the total volume is estimated by constructing a profile from the areas of sample cross sections (measured by planimeter) throughout the extent of the structure studied. In the case of the basal nuclei approximately every 20th or 40th section was measured, and in the case of the cortex and the brain approximately every 100th section was taken. All measurements were made on one side of the brain only (usually the right), hence the figures given in Table I are half-values for the total brain.

The measurements in this series were made on preparations stained for fibers and do not take into account variations of cellular density which may be quite marked, particularly in the case of the pallidum.

The brains selected consist of one sub-primate, the sheep (Ovis); 2 primitive primates, Galago and Perodicticus (potto); 2 monkeys, Cebus and Cercocebus, comparable in development to the often studied rhesus monkey, Macaca mulatta; and the chimpanzee∗ (Pan).

Relative size is indicated in Table II where the volume of each gray mass is expressed in percentage of the total brain volume.