Abstract
The oculomotor system compensates for errors in saccades by a dynamic adaptive process that involves both the motor system and visual representation of space. To study the interaction between the visual and motor representations we designed a saccadic adaptation paradigm where the two representations were in opposite directions. We adaptively increased saccadic amplitudes for rightward saccades (outward adaptation), then measured the landing point for leftward saccades aimed at a target in the same spatial location as that used during adaptation training. These leftward saccades decreased rather than increased in amplitude, to land in the same spatial position as during adaptation, implicating visual signals play a part in saccadic error correction. To examine the coordinate system of the visual signals, we designed a memory double-saccade task that dissociated retinal from spatiotopic coordinates. When the second saccadic target was presented to the same spatial but different retinal position, saccade landing showed strong adaptation; but when presented to the same retinal but different screen position, saccade targeting was unaffected by adaptation. These results suggest that saccadic adaptation fields are strongly influenced by the position of the target in the external world; and conversely, saccadic adaptation changes the memory representation of the visual field, which is in encoded in spatiotopic coordinates.
This study has been funded by the EC project STANIB (FP7-ERC).