[Abstract Title]. - Society for Neuroscience

Authors: *A. ROITMAN 1 , S. G. LISBERGER 1,2,3 ;
1 Dept Physiol, Univ. Calif San Francisco, San Francisco, CA; 2 HHMI, San Francisco, CA; 3 Keck
Ctr. for Integrative Neurosciences, San Francisco, CA
Abstract: Both the cerebellum and the FEFsem are involved in controlling smooth pursuit eye
movements. We have analyzed the activity of Purkinje cells (PCs) in the floccular complex of
the cerebellum during the smooth eye movements evoked by micro-stimulation in the FEFsem.
The monkey pursued step-ramp target motion to the left or the right. In half the trials (randomly
interleaved), a 200-ms train of 50-uA pulses was delivered to the FEFsem 400 ms after the onset
of target motion. The responses of PCs during stimulation of the FEFsem were quite different
from those expected on the basis of the evoked smooth eye velocities. The observed Purkinje cell
responses could not be explained by inputs related to either retinal image motion or efference
copy of the eye movement. The previously reported enhancement of the stimulation effect on the
eye velocity during pursuit compared to that during fixation was confirmed. However, the
enhancement was markedly absent in the PC responses. We suggest that the floccular responses
reflect the gain control signal that emanates from the FEFsem.
The population response to electrical stimulation of the FEFsem provided a command signal that
followed the time course of the evoked eye velocity, but was considerably smaller than predicted
given the responses of the same PCs during smooth eye movement in the absence of the
stimulation. We conclude that the signals from FEFsem may activate another structure, besides
the floccular complex, that also drives smooth eye velocity.
Disclosures: A. Roitman, None; S.G. Lisberger, None.
Poster
264. Eye Movements: Smooth Pursuit
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 264.7/DD24
Topic: D.06.b. Cortex and thalamus
Support: NIH Grant EY12212
Aginsky Estate
NSF Graduate Research Fellowship
Title: Target selection for smooth pursuit eye movements in the frontal pursuit area