MODELING LEARNING IN BRAIN-STEM AND CEREBELLAR SITES RESPONSIBLE FOR VOR PLASTICITY

A simple model of vestibuloocular reflex (VOR) function was used to an alyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway a nd an indirect path via the cerebellum. An optimization analysis of th is model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simu lation results suggests that the preferred error correction signal con trolling gain modification of the VOR is the direct output of the acce ssory optic system (AOS) to the vestibular nuclei vs, a signal relayed through the cerebellum via floccular Purkinje cells. The potential an atomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VO R response. (C) 1998 Elsevier Science Inc.