Early visual evoked potentials are modulated by eye position in humans induced by whole body rotations.
BACKGROUND
To reach and grasp an object in space on the basis of its image cast on the retina requires different coordinate transformations that take into account gaze and limb positioning. Eye position in the orbit influences the image's conversion from retinotopic (eye-centered) coordinates to an egocentric frame necessary for guiding action. Neuroimaging studies have revealed eye position-dependent activity in extrastriate visual, parietal and frontal areas that is along the visuo-motor pathway. At the earliest vision stage, the role of the primary visual area (V1) in this process remains unclear. We used an experimental design based on pattern-onset visual evoked potentials (VEP) recordings to study the effect of eye position on V1 activity in humans.


RESULTS
We showed that the amplitude of the initial C1 component of VEP, acknowledged to originate in V1, was modulated by the eye position. We also established that putative spontaneous small saccades related to eccentric fixation, as well as retinal disparity cannot explain the effects of changing C1 amplitude of VEP in the present study.


CONCLUSIONS
The present modulation of the early component of VEP suggests an eye position-dependent activity of the human primary visual area. Our findings also evidence that cortical processes combine information about the position of the stimulus on the retinae with information about the location of the eyes in their orbit as early as the stage of primary visual area.
Andersson
Frédéric
F
Groupe d'Imagerie Neurofonctionnelle (GIN) UMR6194, CNRS-CEA-University of Caen and Paris 5, GIP CYCERON, BP5229, Bd. Becquerel, 14074 Caen, France. andersson@cyceron.fr
Etard
Olivier
O
Denise
Pierre
P
Petit
Laurent
L
D000328:Adult; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D012399:Rotation; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology; D014794:Visual Fields / Q000502:physiology