Quantitative Analysis of the Evolution and Reorganization of Microstructure in Primates

Abstract

One of the primary goals in neuroscience is to elucidate the relationship between the structure and function of the brain, and yet basic information about the anatomy of specific circuits is often unavailable. Primates exhibit a suite of adaptations for visual predation, and the sense of touch is fundamental to the proprioception that enables smooth, coordinated movement. In this dissertation, we investigated the visual system in a sample of primates adapted to diurnal or nocturnal ecologies in order to identify anatomical changes associated with vision in conditions of high or low levels of light, respectively. In addition, we investigated reorganization of the brainstem following spinal cord injury in order to determine the effect of the timing and extent of injury on anatomical changes supporting the sense of touch. Our major findings indicate a mosaic of changes in visual cortex microstructure across primate evolution that is broadly correlated with visual acuity and behavioral foraging ecology, and we also show the differential effect of the timing of injury upon regional and neuronal atrophy in the cuneate nucleus following deafferentation. Together, these observations provide initial indices of the structural requirements associated with broad changes in visual behavior and the anatomical changes that follow spinal cord injury.