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Science 13 February 2009:
Vol. 323. no. 5916, pp. 940 - 943
DOI: 10.1126/science.1166112
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Reports

A Neural Mechanism for Microsaccade Generation in the Primate Superior Colliculus

Ziad M. Hafed,1* Laurent Goffart,2 Richard J. Krauzlis1

During fixation, the eyes are not still but often exhibit microsaccadic movements. The function of microsaccades is controversial, largely because the neural mechanisms responsible for their generation are unknown. Here, we show that the superior colliculus (SC), a retinotopically organized structure involved in voluntary-saccade target selection, plays a causal role in microsaccade generation. Neurons in the foveal portion of the SC increase their activity before and during microsaccades with sizes of only a few minutes of arc and exhibit selectivity for the direction and amplitude of these movements. Reversible inactivation of these neurons significantly reduces microsaccade rate without otherwise compromising fixation. These results, coupled with computational modeling of SC activity, demonstrate that microsaccades are controlled by the SC and explain the link between microsaccades and visual attention.

1 Systems Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
2 Institut de Neurosciences Cognitives de la Méditerranée, Equipe Dynamique de la Perception Visuelle et de l'Action, UMR 6193, CNRS–Aix-Marseille Universités, 13402 Marseille, France.

* To whom correspondence should be addressed. E-mail: zhafed{at}salk.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Response Properties of Fixation Neurons and Their Location in the Frontal Eye Field in the Monkey.
Y. Izawa, H. Suzuki, and Y. Shinoda (2009)
J Neurophysiol 102, 2410-2422
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A Microsaccadic Rhythm Modulates Gamma-Band Synchronization and Behavior.
C. A. Bosman, T. Womelsdorf, R. Desimone, and P. Fries (2009)
J. Neurosci. 29, 9471-9480
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Electrical Microstimulation of the Fastigial Oculomotor Region in the Head-Unrestrained Monkey.
J. Quinet and L. Goffart (2009)
J Neurophysiol 102, 320-336
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Firing Patterns in Superior Colliculus of Head-Unrestrained Monkey during Normal and Perturbed Gaze Saccades Reveal Short-Latency Feedback and a Sluggish Rostral Shift in Activity.
W. Y. Choi and D. Guitton (2009)
J. Neurosci. 29, 7166-7180
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E-Letters:

Read all E-Letters

A Neural Mechanism for Fixation Instability
Martin Rolfs
Science Online, 2 Jun 2009 [Full text]
Reply to M. Rolfs' E-Letter
Ziad M. Hafed, et al.
Science Online, 2 Jun 2009 [Full text]

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