Sensitivity to touch is known to be different between "passive" touch when an object simply touches the skin, and "active" touch when an object is felt by moving touch. We know very little about the mechanisms in the brain that underlie these differences. This project exploits a novel approach recently developed using rodent whiskers as a model system. Rodents actively explore surfaces using characteristic "whisking" movements of their array of whiskers called facial vibrissae. Recent work has shown that texture discrimination by rats using their vibrissae is excellent, comparable to primates using their fingertips, and that the behavioral strategies for discrimination are similar. The rat whisker system is particularly well-suited for study because a lot is known about its elegant anatomical orderly projection to the brain, and because the whiskers are easily accessible for harmless manipulation and observation. This project uses a novel combination of animal training, computer-assisted movement analysis, and electrophysiological recordings from single nerve cells to investigate this active touch. The relationship between whisking contact, activity in peripheral neurons and activity in central cortical neurons is compared, and the role of multiple whiskers and of sensory experience is explored. Results from this work will have an impact beyond somatosensory neuroscience toward better understanding how animals use actively driven sensory behavior in general, how sensory experience and learning enhance discrimination, and more generally how the brain acquires and processes information.
