Animals perceive their surroundings both through sensory systems that transduce environmental features and through motor systems that control how those features are received. This perception, distinct from its building blocks of sensation and motion, is constructed in the nervous system by the integration of modalities. While the neural substrates of this construct are often studied by reducing perceptual systems into more simple sensory and motor components, this dissertation takes the complementary approach of studying such active sensory processes by considering the simple rat vibrissa model system in which these components are integrated to create spatial perception. We develop a conceptual and behavioral framework for the study of these integration processes in three main parts. ChapterĨI introduces the rat vibrissae and divides earlier behavioral experiments in the system into two categories of environmental features, texture and location. After brief observations on texture processing, we focus on the question of spatial perception and build on previous work demonstrating that sensory and motor streams are intermixed in the vibrissa system. We then develop a quantitative approximation of vibrissa motion to categorize potential algorithms for decoding the position of environmental objects. ChapterĨII presents an aside in which we consider evidence for frequency mixing in the rat and other nervous systems. We describe an algorithm that can isolate particular components from the mixing that results from neuronal thresholds. This mixing computation is offered as a potential substrate for the phase difference algorithms described in ChapterĨI. ChapterĨV develops the main experimental work of the dissertation. Rats are challenged with a psychophysical test of their ability to discriminate object location using only vibrissa tactile cues through a single vibrissa. The ability of animals to perform this task with this restricted sensory apparatus constrains the algorithms discussed in ChapterĨI and argues that the rat brain in fact integrates sensory and motor streams to inform perception. ChapterṼ concludes the dissertation with a brief demonstration of electrophysiological techniques that characterize neural activity over cortical large areas. Through experiments such as these, our single vibrissa results can be related to the function of the complete vibrissa array

While investigating a signal of adaptive evolution in humans at the gene LARGE, we encountered an intriguing finding by Dr. Stefan Kunz that the gene plays a critical role in Lassa virus binding and entry. This led us to pursue field work to test our hypothesis that natural selection acting on LARGE-detected in the Yoruba population of Nigeria-conferred resistance to Lassa Fever in some West African populations. As we delved further, we conjectured that the emerging nature of recently discovered diseases like Lassa fever is related to a newfound capacity for detection, rather than a novel viral presence, and that humans have in fact been exposed to the viruses that cause such diseases for much longer than previously suspected. Dr. Stefan Kunzs critical efforts not only laid the groundwork for this discovery, but also inspired and catalyzed a series of events that birthed Sentinel, an ambitious and large-scale pandemic prevention effort in West Africa. Sentinel aims to detect and characterize deadly pathogens before they spread across the globe, through implementation of its three fundamental pillars: Detect, Connect, and Empower. More specifically, Sentinel is designed to detect known and novel infections rapidly, connect and share information in real time to identify emerging threats, and empower the public health community to improve pandemic preparedness and response anywhere in the world. We are proud to dedicate this work to Stefan Kunz, and eagerly invite new collaborators, experts, and others to join us in our efforts.