[Abstract Title]. - Society for Neuroscience

input to the pursuit system and neurons in MT are tuned for both direction and speed of motion.
Therefore MT is an ideal candidate area to be a source of sensory variation. If pursuit variation
arises from MT, then there should be significant trial-by-trial correlations between the variation
in individual MT responses and the associated pursuit eye velocity vector. We recorded from
single neurons in macaque area MT during a standard step-ramp pursuit task. The pursuit target,
a patch of coherently moving random dots, appeared in the receptive field of a neuron and
moved in a given direction at a given speed. For each neuron, we tested different directions
and/or speeds and each condition was balanced with equal numbers of target motions in the
opposite direction to minimize anticipatory responses. We found significant trial-by-trial
correlations between the firing rate of MT neurons and eye velocity. The correlations appeared
consistently and were uniformly positive in many trial conditions across many neurons at the
onset of the transient neural response. Whether firing rate and velocity were correlated depended
on the stimulus rather than the neuron under study. The correlation values were greater for trial
conditions that evoked higher firing rates. At times later in the neural response but still in the
first 100 ms of pursuit, we found trial-by-trial correlations with statistical significance in excess
of chance, but with equal numbers of positive and negative correlations. Our results show that
neurons as early in the pursuit pathway as visual area MT contribute to variation in the initiation
of smooth pursuit eye movements. The patterns of correlations can help us constrain how
downstream areas decode the population response in MT to guide pursuit eye movements.
Disclosures: S.S. Hohl, None; S.G. Lisberger, None.
Poster
264. Eye Movements: Smooth Pursuit
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 264.5/DD22
Topic: D.06.d. Saccades and Pursuit
Support: NIH Grant EY013308
RR00165
Title: Neural activity in MSTd during short perturbations of ongoing smooth pursuit eye
movements
Authors: *U. R. BUTTNER 1 , S. ONO 2 , M. J. MUSTARI 2 , S. GLASAUER 1 , U. NUDING 1 ;
1 Dept Neurol Klinik Grosshadern, Univ. Munchen, 81377 Munchen, Germany; 2 Yerkes Natl.
Primate Res. Center, Emory Univ., Atlanta, GA