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Steffen Klingenhoefer, Markus Wittenberg, Thomas Wachtler, Frank Bremmer; Spatial representation during saccade adaptation in macaque areas V1 and V4. Journal of Vision 2009;9(8):758. doi: 10.1167/9.8.758.
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© ARVO (1962-2015); The Authors (2016-present)
The saccadic system is capable of rapidly adapting to changes in the oculo-motor system (e.g. changes in the mechanics of the eyeball) that otherwise would lead to movement inaccuracy and poor vision - an effect usually referred to as saccade adaptation. This adaptation challenges the mechanisms that guarantee visual perceptual stability across eye-movements - the neural basis of which is currently unknown. We hypothesized that perceptual stability during saccade adaptation would require a modulation of the visual RFs with respect to the fovea to compensate for the mismatch between sensory and motor signals. In our current study we therefore mapped visual receptive fields (RFs) in areas V1 and V4 of the macaque monkey during a saccade adaptation task.
RFs were mapped by presenting Gaussian luminance patches at random positions under three different conditions: during fixation, in a classical saccade task and during saccade adaptation. Saccade adaptation was elicited by a perisaccadic displacement of the saccade target against the direction of the eye movement (Backward adaptation). To obtain spatiotemporal RFs we analyzed multi-unit activity using a stimulus response correlation technique.
Preliminary data suggest that, in both areas RF positions were different during saccade adaptation trials as compared to fixation or non-adapted saccade trials. In adaptation trials, RF locations calculated from stimuli presented immediately after saccade offset were shifted in the direction of the saccade (i.e. opposite to the direction of the target displacement) compared to control trials. This displacement was larger for RFs mapped in V4 than in V1. In both areas, however, the magnitude of RF shift decreased slightly during the course of adaptation.
We conclude that eye movement signals do have an influence on spatial information processing in areas V1 and V4 - a mechanism probably involved in the maintenance of perceptual stability across saccadic eye movements.
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