A serial section Golgi analysis of the primate claustrum

Abstract

The cellular composition of the primate claustrum was analyzed using serially sectioned Golgi impregnated neurons. The tissue used in this study was embedded in a soft resin mixture and cut with 25 mm long glass knives. The resin embedding allowed the sections to be cut serially at a thickness of only 3 micrometers. A camera lucida was employed for drawing the cellular processes from selected impregnated neurons; these drawings were later incorporated into a single composite picture of the neuron. Three types of neurons were observed in the primate claustrum. The largest of these neurons (Type 1) had a cell body and spine-laden dendritic arborization that varied in size and shape according to the neuron's position in the claustrum. The axons of Type I neurons were successfully impregnated in 25-day-old animals and were found to form collaterals within the claustrum. The collaterals from the axons of these cells appeared to leave the claustrum through both the external and extreme capsules. A second neuron found in the claustrum (Type II) had a round cell body with smooth beaded dendrites which radiated in all directions. The axon of the Type II neuron appeared to give off numerous collaterals that were not observed to leave the claustrum. A third type of neuron (Type III) had a small pear shaped cell body and a sparse dendritic tree. The axon and its collaterals appeared to remain within the dendritic circumference of the Type III neuron.

Comparative Anatomy of the Claustrum in Selected Species: A Morphometric Analysis

“…In both species, the claustrum forms a characteristic thin layer of gray matter, which we did not observe in representatives of any of the other mammalian orders. Similar to reports of other authors, we observed differences in shape and spatial orientation of neurons situated in narrow and wide fragments of the claustrum [Brand, 1981].…”

Percentage of Projection Neurons and Various Types of Interneurons in the Human Claustrum

“…1982], They differ from each other in the size of their cell body and the pattern of pigmentation. Very similar large and small nonspiny nerve cells have been described in the claustrum of the monkey brain as well and, on account of their axonal characteristics, have been classified as local circuit neurons [Brand, 1981]. We therefore consider the type 11-type V cells as interneurons of the human claustrum.…”

What is the function of the claustrum?

“…There is general agreement that the most common cell type, called type I, is a large cell whose dendrites are covered by spines (for the relevant Golgi studies in cats, monkeys and humans see, respectively; LeVay & Sherk 1981a;Brand 1981;Braak & Braak 1982). The axons of these type I cells, after throwing off local collaterals, often leave the claustrum either medially or laterally (figure 4a).…”