E.J. Tehovnik, W.M. Slocum and P.H.
Schiller, 2006
Soc Neurosci. Abstr., 545.1.
Abstract
Electrical microstimulation of macaque striate cortex (area V1) delays the execution
of saccadic eye movements made to a visual target placed in the receptive field
of the stimulated neurons (Tehovnik et al. 2005). The region of visual space
within which saccades are delayed is called a delay field. We examined the effects
of changing the parameters of stimulation and target size on the size of a delay
field. Rhesus monkeys were required to generate a saccadic eye movement to a
bright punctate visual target presented within or outside the receptive field
of the neurons under study. On 50% of trials, a train of stimulation comprised
of 0.2-ms anode-first pulses was delivered to the neurons before the onset of
the visual target. Stimulations were performed in the operculum at 0.9 to 2.0
mm below the cortical surface. It was found that increases in current (50 to
100 mA), pulse frequency (100 to 300 Hz), or train duration (100 to 300 ms)
increased the size of a delay field and increases in target size (0.1 to 0.2
degrees of visual angle) decreased the size of a delay field. Delay fields varied
in size between 0.1 and 0.6 degrees of visual angle. When electrical stimulation
was delivered at target onset, there was no longer a delay in visually-guided
saccades. We suggest that the delay effect observed by microstimulation of V1
is due to the activation of GABAergic circuits within V1.
Support Contributed by: NIH EY014884
Citation: E.J. Tehovnik, W.M. Slocum and P.H. Schiller Delay fields produced by microstimulation of macaque V1. Program No. 545.1. 2006 Neuroscience Meeting Planner. Atlanta, GA: Society for Neuroscience, 2006. Online.