| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
We investigated correlation between the eye movement and temporal simple-spike (SS) frequency of the Purkinje cell in the cerebellar flocculus middle-zone during optokinetic response (OKR) in alert cats. Time course of the temporal SS-rate at a given time delay (mean, 11 ins) was well reconstructed with coefficient of determination > 0.7 by a linear weighted superposition of the eye acceleration (mean coefficient, 0.076 spikes/s per deg/s2), velocity (5.19 spikes/s per deg/s), position (-2.89 spikes/s per deg), and bias (mean, 35.8 spikes/s), Magnitude of the contribution of each component to the regression was estimated, and three cell types were found : Velocity-Position-Acceleration (VPA) type (n=19), contribution of velocity, position, and acceleration components is significant (P < 0.05) ; Velocity-Position (VP) type (n=9), velocity and position components are significant ; Velocity-Acceleration (VA) type (n=2), velocity and acceleration components are significant. Using a single set of the coefficients for 5 deg/s stimulus velocity, the SS rate during higher (10, 20, and 40 deg/s) stimulus velocities were successfully reconstructed, suggesting generality of the model. The eye-position information encoded in SS-firing during OKR is relative but not absolute in the sense that the magnitude of the position shift contributes to the firing-rate change regardless of the initial eye-position. It is concluded that 1) the temporal SS-firing frequency in the cat middle-zone encodes the velocity and acceleration information for controlling the viscosity- and inertia-forces, respectively, during short-duration horizontal OKR and 2) the position information encoded in the SS-firing is not sufficient for controlling the elastic force during] OKR.
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