The sense of touch is critical for interacting with the physical world. In order to respond to complex tactile stimuli, the nervous system must integrate patterns of spikes across populations of primary mechanoreceptor neurons. However, the mechanisms used by the nervous system to detect complex mechanical stimuli are not known. In order to understand how the central nervous system processes peripheral mechanosensory information, I propose to study the central coding of touch in the genetic model organism, Drosophila. As in mammals, the fly's body surface is covered with primary mechanosensory organs. Among these mechanoreceptors, the tactile bristles are particularly amenable to investigation because they can be stimulated independently of each other and are sufficient to drive postural reflexes and grooming behavior. Little is known, however, about the neural coding of touch stimuli within bristles or in downstream circuits. I will perform experiments to address two specific questions: 1) what classes of central neurons integrate signals from mechanosensory bristles and 2) how do these central neurons process their inputs to detect specific patterns of bristle stimulation? To answer the first question, I will screen genetic drive lines for central neurons that receive direct input from mechanosensory bristles. I will then use whole-cell patch-clamp electrophysiology to investigate specific mechanisms of spatial and temporal integration. By tracing the flow of sensory signals from primary receptor neurons to synaptic integration in the central nervous system, I hope to identify fundamental mechanisms of neural coding that are highly relevant for central disorders of mechanosensory processing in humans, such as chronic pain and itch.
Abnormalities in the neural processing of touch are among the most common medical disorders experienced by Americans;for example, approximately 30% of people in the US suffer from chronic pain. Studies in Drosophila have already contributed greatly to our understanding of how the peripheral nervous system detects mechanical and noxious stimuli. Further investigation of the basic neural computations that underlie touch processing may lead to interventions and therapies for mechanosensory disorders, such as deep brain stimulation for treating neuropathic pain.