Pre-motor Neural Circuits for Exploratory Movement Abstract Movements performed by animals in order to explore external objects are called "exploratory movements". Humans use delicate and complex movements of fingers/fingertips to discern the texture, shape and other physical properties of objects, and to manipulate tools. Rodents explore their physical environment through rhythmic sweeping of their vibrissae ("whisking"), and thus serve as a major model for studying neural circuits controlling exploratory touch movements. The final common control of the tactile vibrissae is provided by motor neurons located in the lateral facial nucleus (vFMNs). The objective of this proposal is to discover and characterize the "premotor circuitry" that directly regulates the activities of vFMNs. We will identify the "connectivity maps" of premotor neurons that provide monosynaptic input for the different vFMNs controlling vibrissa protraction and retraction. We wil also determine the "neurotransmitter phenotypes" of identified premotor neurons, and characterize the functional inputs of different premotor neurons onto vFMNs using electrophysiological and optogenetic approaches. Furthermore, we will determine how developmental changes in the vFMN premotor circuitry enable the postnatal emergence of bilaterally coordinated and often synchronized exploratory whisking behavior. Identifying the structural and functional wiring diagram of these premotor neural circuits is a critical step for investigating the generation and voluntary control f exploratory movements. Results from this study will also provide new foundations for understanding motor control of hand and finger movements in humans, and thus can help lead to the design of superior neuroprosthetics devices to restore exploratory movements following paralysis or amputation.
This proposal uses newly developed monosynaptic rabies virus based trans-synaptic tracing methods combined with electrophysiology and optogenetics to precisely identify and characterize the premotor neural circuits that control exploratory activ touch movements in mouse. Understanding neural circuits generating and controlling active touch movements will help design better neuroprosthetics for amputated or paralyzed patients. It is also expected that results obtained from this study will lead to the discovery of neural circuits for sensorimotor integration underlying complex movements, which is relevant to treating a wider range of neurological disorders in which the sensorimotor loop is damaged.
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