| Like humans, non-human primates are frontal eyed animals that rely heavily upon binocular vision to navigate through the environment. Particularly important for humans and nonhuman primates alike is the ability to place the images of important and/or interesting objects on the fovea for detailed viewing. It is thus not surprising that in parallel with the evolution of this sensory specialization is an elaborate system of oculomotor control. Humans make on the order of three rapid (saccadic) eye movements every second during normal viewing with each saccade having the potential to reveal new information about the external environment. Though seemingly made with great haste, saccadic eye movements are not issued randomly. On the contrary, saccades are voluntary and deliberate with decisions about where to look the product of both extrinsic (stimulus based) and intrinsic (behavioral state) factors.; Underlying the generation of saccadic eye movements is a highly distributed neural network consisting of numerous cortical and sub-cortical areas. Presumably, these regions work in parallel to encode sensory information, decide upon a course of action, and issue the motor command to those efferent structures capable of carrying it out. Recent emphasis on the neural correlate of decision-making has naturally led to the study of cortical visuomotor territories. It is clear, however, that cortico-sub cortical loops may play an important role in these and other such high-order computations (e.g., working memory).; Central thalamus, the subject of this thesis, is one sub cortical area that, from an anatomical point of view, seems well positioned to participate in such computational loops. However, as described below, the properties of neurons in this region are largely unknown. This thesis consists of three studies. The first examines the essential visuomotor properties of neurons in central thalamus. The second determines if central thalamic neurons have the potential to participate in the process of visuo-spatial working memory. Finally, the third details results from behavioral experiments designed to examine a prevailing concept relating to the neural basis of perceptual decision-making. |
