Microsaccade
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{{Otheruses|Eye movement (disambiguation)}}
'''Microsaccades''' are a kind of [[fixational eye movement]]. They
are small, jerk-like, involuntary [[eye movements]], similar to
miniature versions of voluntary [[saccade]]s. They typically occur
during prolonged visual [[fixation (visual)|fixation]] (of at least several seconds),
not only in humans, but also in other animals, especially those with
[[fovea]]l vision ([[primate]]s, [[cat]]s, etc.). Microsaccade
amplitudes vary from 2 to 120 [[arcminute]]s.
The role of microsaccades in [[visual perception]] has been a highly
debated topic which is still largely unresolved. It has been proposed
that microsaccades correct displacements in eye position produced by drifts, although non-corrective
microsaccades also occur. Microsaccades were also believed to prevent
the [[retina]]l image from fading, but they do not occur often enough
for that purpose, considering that perfectly [[stabilize]]d images can
disappear from perception in a few seconds or less. The current
consensus is that all fixational eye movements are important for
the maintenance of visibility.
Experiments in [[neurophysiology]] from different laboratories showed
that fixational eye movements, particularly microsaccades,
strongly modulate the activity of [[neurons]] in the visual areas of
the [[macaque]] [[brain]]. In the [[lateral geniculate nucleus]] (LGN)
and the [[primary visual cortex]] (V1), microsaccades can move a
stationary stimulus in and out of a [[neuron]]'s [[receptive field]],
thereby producing transient neural responses. Microsaccades might
account for much of the response variability of neurons in visual area
V1 of the awake monkey.
Current research in visual [[neuroscience]] and [[psychophysics]] is
investigating how microsaccades relate to fixation correction, control
of binocular [[fixation disparity]] and [[attention]]al shifts.
== See also ==
* [[Rapid eye movement sleep]]
* [[Saccade]]
==References==
=== Notes ===
{{reflist|colwidth=40em}}
=== Bibliography ===
{{refbegin}}
* R. H. S. Carpenter. ''Movements of the Eyes'' (Pion, London, 1988).
* Susana Martinez-Conde, Stephen L. Macknik & David H. Hubel. The role of fixational eye movements in visual perception. ''Nature Reviews Neuroscience'' 5(3):229-240 (2004). [http://dx.doi.org/10.1038/nrn1348 doi:10.1038/nrn1348]
{{refend}}
[[Category:Eye]]
[[de:Mikrosakkade]]