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Shawn Xu

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Primary Appointment: Life Sciences Institute-Admin
Primary PIBS Dept.: Molecular and Integrative Physiology
Other PIBS Depts.: Neuroscience
PubMed Name: xu x z shawn
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  We are interested in understanding some of the fundamental questions in neuroscience: How are sensory inputs perceived by the nervous system? How do neural circuits process information to generate behavior? How do genes and drugs of abuse regulate these processes? ? We also investigate how sensory cues and genes modulate aging and longevity. To address these questions, we use the genetic model organism C. elegans because of its simple and well characterized nervous system. We take a multidisciplinary approach combining molecular genetics, cell biology, behavioral analysis, functional imaging, and electrophysiology.

Sensory transduction and behavior:

The environment has a profound impact on animal behavior. The ability to sense environmental cues to adjust its behavior is essential for an animalís life. There are five common sensory modalities in mammals: vision, smell, taste, hearing and touch. In addition, we rely on proprioception, which is often referred to as the sixth sense, to control body posture, balance and movement. Among the most common sensory stimuli are chemicals (smell and taste), mechanical forces (touch, hearing and proprioception), light (vision), and temperature. We are particularly interested in understanding how sensory neurons detect and transduce mechanical, chemical, and light signals to generate behavioral output, and how gene networks (e.g. receptors, ion channels and signaling molecules) regulate these processes.

Neural circuits and synaptic mechanisms underlying behavior and drug addiction:

One of the ultimate goals of neuroscience research is to understand how the nervous system controls behavior. As neural circuits are the functional units of the nervous system, mapping the functional components of neural circuits and dissecting the synaptic mechanisms by which the circuits process information hold the key to understanding the neural basis of behavior and addiction. C. elegans has recently emerged as an excellent model for approaching these questions because of its simple and very well characterized nervous system. We have developed novel tools to quantify behavior and record neural circuit and synaptic activities, which would greatly facilitate the dissection of neural circuit and synaptic mechanisms underlying behavior. We currently focus on sensory behaviors and drug dependent behaviors. To do so, we take a multidisciplinary approach combining functional imaging, molecular genetics, behavioral analysis, and electrophysiology.

Sensory and genetic modulation of aging and longevity:

Sensory cues not only regulate an animalís behavior but also its physiology, for example, aging and longevity. In addition to nutrients, other environmental cues, such as thermo- and chemo-sensory inputs, have a profound impact on aging and longevity. For example, both cold- and warm-blooded animals live longer at lower body temperatures, highlighting a general role of temperature in lifespan regulation. However, the underlying mechanisms remain largely unknown. We have recently identified TRPA1, a cold-sensitive ion channel, as a thermo-sensor that detects temperature decreases in the environment to extend lifespan, demonstrating that genes actively promote longevity at cold temperatures. This calls into question the century-old view that cold-dependent lifespan extension is a passive thermodynamic process. We are interested in identifying new genes and pathways that mediate temperature-dependent lifespan regulation in C. elegans. Ultimately, we would like to derive a thorough understanding of how sensory cues modulate aging and longevity.