The reference frames in saccade adaptation 3 4

4 Eckart Zimmermann 5 Cognitive Neuroscience Section, Institute of Neuroscience and Medicine (INM-3), 6 Research Center Jülich, Germany 7 [email protected] 8 9 Abstract 10 11 Saccade adaptation is a mechanism which adjusts saccade landing positions if they systematically 12 fail to reach their intended target. In the laboratory, saccades can be shortened or lengthened if the 13 saccade target is displaced during execution of the saccade. Here, saccades were performed from 14 different positions to an adapted saccade target to dissociate adaptation to a spatiotopic position in 15 external space from a combined retinotopic and spatiotopic coding. The presentation duration of 16 the saccade target before saccade execution was systematically varied during adaptation and 17 during test-trials, with a delayed saccade paradigm. Spatiotopic shifts in landing positions 18 depended on a certain preview duration of the target before saccade execution. When saccades 19 were performed immediately to a suddenly appearing target, no spatiotopic adaptation was 20 observed. These results suggest that a spatiotopic representation of the visual target signal builds 21 up as a function of the duration the saccade target is visible before saccade execution. Different 22 coordinate frames might explain the separate adaptability of reactive and voluntary saccades. 23 Spatiotopic effects were found only in outward adaptation but not in inward adaptation, which is 24 consistent with the idea that outward adaptation takes place at a the level of the visual target 25 representation, while inward adaptation is achieved at a purely motor level. 26 27 Articles in PresS. J Neurophysiol (January 16, 2013). doi:10.1152/jn.00743.2012