Effect of the slow transient phenomenon of a synaptic modification on vestibulo-ocular reflex adaptation

Abstract

According to the experimental studies, the duration of the transient phenomenon of the synaptic modification involved in vestibulo-ocular reflex (VOR) adaptation lasts considerably long after the synaptic inputs. In the present article, effect of the transient phenomenon on VOR adaptation is studied by incorporating the transient phenomenon into the cerebellar model proposed by Fujita. In the present extended model, it is assumed that the synaptic modification is a modification of the concentrations of reactants and products for a certain reaction. The synaptic efficacy is given by the concentration of products. The model of reaction includes the supply of reactants and flux of reactants and products out of the reaction system. The supply of reactants is induced by correlation between two different types of input signals, which has been considered to be proportional to the amount of the synaptic modification at the moment. The flux produces natural recovery of the synaptic modification, which was observed in experiments. The simulation results suggest that VOR adaptation takes two types of courses according to the efficiency of the reactant supply to the synaptic inputs under the slow transient phenomenon of the synaptic modification. The present extended model gives approaches to control mechanisms of VOR adaptation.