Spatiotemporal Structure of Sensory Acquisition Behaviors: Experiments on the Rat Vibrissal System

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When you explore an object using your hands, or you change your footsteps based on the type of surface you are walking on, your sense of touch is seamlessly combined with the movements you make. How does your brain accomplish this feat? This is a large, open question that is difficult to answer using human studies alone. This project will investigate this question by studying the rat whisker (vibrissal) system. Rats move their whiskers back and forth to touch and explore different objects, much as humans use their hands. The tactile information is conveyed from the base of the whiskers through a series of processing stages in the brain. This research project focuses on understanding the processing that occurs in the second stage, in a brain structure called "spinal trigeminal nucleus interpolaris" (SpVi). In the first part of the project, computer simulations and robotic models will be used to test the plausibility of the different types of processing that might occur in SpVi. In the second part of the project, technology to measure the precise contact times and locations of a rat's whiskers with different objects will be developed. Finally, in the third part of the project, electrical signals from neurons in SpVi, will be recorded and correlated with the animal's ongoing behavior as it touches different objects. The results that emerge will allow the testing of three different hypotheses for the processing that occurs in SpVi. Regardless of which hypothesis(es) is/are found to be correct, the results will improve the understanding of how the brain combines sensing and movement to allow animals to perceive the world. This project will contribute to the interdisciplinary training of two graduate students and to ongoing graduate-level course development at Northwestern University. It will also provide meaningful research opportunities in engineering for at least six undergraduates, with a specific effort made to include women and underrepresented minorities.