E.J. Tehovnik, W.M. Slocum and P.H.
Schiller, 2005
Soc Neurosci. Abstr., 509.14.
Abstract
Electrical microstimulation of macaque primary visual cortex (area V1) results
in a significant delay in the execution of saccadic eye movements made to a
punctate visual target located in the receptive field of the stimulated neurons
(Tehovnik et al., 2004). In the current study we examined the spatial extent
of this interference effect by placing a visual target systematically at various
locations relative to the receptive field of the stimulated neurons. A 100-ms
train of stimulation comprised of anode-first pulses (presented at 200 Hz using
currents at or less than 100 uA) was delivered to V1 immediately before a monkey
generated a saccade to the visual target. The size of the target was 0.2 degrees
of visual angle. All stimulations were performed between 1 and 2 mm below the
cortical surface. At the current levels used, the estimated region of tissue
activated was within 0.5 mm from the electrode tip. The size of the visual field
affected by the stimulation increased as the stimulation site was further from
the foveal representation of V1. The size of this field varied from 0.1 to 0.6
degrees of visual angle. The shape of this field was roughly circular. These
results are consistent with the finding that phosphenes evoked by stimulating
near the foveal representation of human V1 tend to be smaller than those evoked
from the peripheral representation. Also phosphenes tend to exhibit a circular
configuration.
Support Contributed By: NIH EY014884
Citation: E.J. Tehovnik, W.M. Slocum, P.H. Schiller. USING ELECTRICALLY EVOKED INTERFERENCE IN MACAQUE V1 TO STUDY THE PROPERTIES OF PHOSPHENES Program No. 509.14. 2005 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2005. Online.