Brian W. Quist, Ph.D. - US grants

DESCRIPTION (provided by applicant): The vibrissal-trigeminal system of the rodent is one of the most important model systems in neuroscience to examine how animals integrate sensory and motor information to form a perception. Each year, hundreds of neuroscience studies examine neural responses to various patterns of whisker stimulation. Unfortunately, the interpretation of these studies is severely limited. Are the patterns of whisker stimulation behaviorally appropriate? Are the sequences of velocities and applied torques consistent with those that would occur during natural exploratory behavior? What are the spatiotemporal patterns that should be used in anesthetized experiments to mimic natural behavior? In order to understand the general functional principles that govern the trigeminal neural circuits mediating whisker sensing and control, these questions must be answered. This proposal fills this large gap in our knowledge. The objective of this proposal is to develop an anatomically and dynamically-accurate computer simulation of the mechanics of the entire whisker array, and to use the model to predict the natural spatiotemporal patterns of whisker contact and bending. The construction of this "digital rat" will involve three aims that gradually build up the answer to this important question, from the isolated whisker to the full array. In Aim 1, I will quantify the contribution of dynamics to free-air whisking and whisker/object contact in the isolated whisker. This will result in a dynamically-accurate model of the whisker. In Aim 2, I will use an unrestrained rat whisking in free-air to quantify the natural motion of the base of each whisker in the array. I will then determine the boundary condition at the base that best matches natural whisking motion using the dynamic model. In Aim 3, unrestrained rats will be trained to whisk across a platform into a custom-built wall instrumented to signal contact timing and location. This data will be compared to a full dynamic simulation of the vibrissal array (the "digital rat"). The focus of Aim 3 is to determine the necessary degrees of freedom at the whisker base to predict natural spatiotemporal patterns of whisker-object contact. The final outcome of the proposed work - an accurate 3D dynamic model of the rat head and vibrissal array - will be of tremendous use to researchers studying all levels of the trigeminal pathway, as well as to researchers constructing models of antennal movements in invertebrates. PUBLIC HEALTH RELEVANCE: Doctors could help many more people with brain injury and stroke if there were a better understanding of the relationship between movement and the sense of touch. The rat whisker system is one of the best studied models for understanding this relationship. However, researchers have not yet characterized how whiskers interact with objects. The proposed work will develop a general tool that permits whisker-object patterns to be quantified, in turn permitting researchers to better understand the signals processed by the parts of the brain that deal with sensing and movement.