title: Tactile modulation of whisking via the brainstem loop: statechart modeling and experimental validation.
abstract: Rats repeatedly sweep their facial whiskers back and forth in order to explore their environment. Such explorative whisking appears to be driven by central pattern generators (CPGs) that operate independently of direct sensory feedback. Nevertheless, whisking can be modulated by sensory feedback, and it has been hypothesized that some of this modulation already occurs within the brainstem. However, the interaction between sensory feedback and CPG activity is poorly understood. Using the visual language of statecharts, a dynamic, bottom-up computerized model of the brainstem loop of the whisking system was built in order to investigate the interaction between sensory feedback and CPG activity during whisking behavior. As a benchmark, we used a previously quantified closed-loop phenomenon of the whisking system, touched-induced pump (TIP), which is thought to be mediated by the brainstem loop. First, we showed that TIPs depend on sensory feedback, by comparing TIP occurrence in intact rats with that in rats whose sensory nerve was experimentally cut. We then inspected several possible feedback mechanisms of TIPs using our model. The model ruled out all hypothesized mechanisms but one, which adequately simulated the corresponding motion observed in the rat. Results of the simulations suggest that TIPs are generated via sensory feedback that activates extrinsic retractor muscles in the mystacial pad. The model further predicted that in addition to the touching whisker, all whiskers found on the same side of the snout should exhibit a TIP. We present experimental results that confirm the predicted movements in behaving rats, establishing the validity of the hypothesized interaction between sensory feedback and CPG activity we suggest here for the generation of TIPs in the whisking system.
authors: Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel ; Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
authors: Dana
authors: D
authors: Sherman
authors: Tess
authors: T
authors: Oram
authors: Dudi
authors: D
authors: Deutsch
authors: Goren
authors: G
authors: Gordon
authors: Ehud
authors: E
authors: Ahissar
authors: David
authors: D
authors: Harel
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001933:Brain Stem / Q000502:physiology*; D056228:Feedback, Sensory; D008954:Models, Biological; D051381:Rats; D014738:Vibrissae / Q000502:physiology*