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The Journal of Neurophysiology Vol. 84 No. 5 November 2000, pp. 2691-2694
Copyright ©2000 by the American Physiological Society
RAPID COMMUNICATION
Department of Physiological Optics, University of Alabama at Birmingham, Birmingham, Alabama 35294
Gawne, Timothy J. and
Julie M. Martin.
Activity of Primate V1 Cortical Neurons During Blinks. J. Neurophysiol. 84: 2691-2694, 2000. Every
time we blink our eyes, the image on the retina goes almost completely
dark. And yet we hardly notice these interruptions, even though an
external darkening is startling. Intuitively it would seem that
if our perception is continuous, then the neuronal activity on which
our perceptions are based should also be continuous. To explore this
issue, we compared the responses of 63 supragranular V1 neurons
recorded from two awake monkeys for four conditions: 1)
constant stimulus, 2) during a reflex
blink, 3) during a gap in
the visual stimulus, and 4) during an external
darkening when an electrooptical shutter occluded the entire
scene. We show here that the activity of neurons in visual cortical
area V1 is essentially shut off during a blink. In the 100-ms epoch
starting 70 ms after the stimulus was interrupted, the firing rate was
27.2 ± 2.7 spikes/s (SE) for a constant stimulus, 8.2 ± 0.9 spikes/s for a reflex blink, 17.3 ± 1.9 spikes/s for a gap, and
12.7 ± 1.4 spikes/s for an external darkening. The responses
during a blink are less than during an external darkening
(P < 0.05, t-test). However, many
of these neurons responded with a transient burst of activity to the
onset of an external darkening and not to a blink, suggesting that it
is the suppression of this transient which causes us to ignore blinks.
This is consistent with other studies where the presence of transient
bursts of activity correlates with the perceived visibility of a stimulus.
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