The remapping phenomenon demonstrates the necessary temporal properties for monkeys to solve the double step task

(Batista et al., 1999; Colby et al., 1996; Duhamel et al., 1992; Kusunoki and Goldberg, 2003; Sommer and Wurtz, 2006). Receptive field remapping must be driven Target Selective Inhibitor Library screening by a corollary discharge of the motor command because it can occur before the eye movement. It therefore avoids the perisaccadic errors that would arise if the brain used a gain-field mechanism to calculate target position. That the brain depends upon a corollary discharge of the first saccade to perform the double-step saccade is shown by two studies: (1) the corollary discharge signal www.selleckchem.com/products/abt-199.html that shifts receptive fields in the frontal eye field around the time of a saccade arises from the superior colliculus via the medial dorsal nucleus

of the thalamus. Reversible lesions in the medial dorsal nucleus of the thalamus impair the monkeys’ performance in the double-step task (Sommer and Wurtz, 2002). (2) Humans with parietal lesions cannot perform the double-step task accurately because they cannot compensate when the first saccade is made in the direction contralateral to the lesion (Wardak et al., 2002). These findings demonstrate the important role of corollary discharge and receptive field remapping in maintaining the spatial accuracy of saccade targets across eye movements. It is possible that receptive field remapping contributed to the inaccuracy of perisaccadic modulation of visual responses by eye position. We mapped the receptive

fields carefully at the center of gaze, but placed the probe only at the most effective stimulus location in the two- and three-saccade tasks. If receptive field geometry changed as a function of the conditioning saccade, the probe might stimulate a less effective portion of the receptive field mafosfamide and appear to evoke a gain-field effect. This is, however, unlikely to explain the observed patterns of immediate postsaccadic responses for two reasons. The first is that although perisaccadic remapping can modulate receptive field shapes immediately after the saccade (Kusunoki and Goldberg, 2003), this effect is over by 150 ms, a time at which all consistent and inconsistent cells still exhibit spatially inaccurate visual responses. V4, which has a robust projection to LIP (Baizer et al., 1991), exhibits similar perisaccadic receptive field shifts, but these too resolve by 150 ms after the saccade (Tolias et al., 2001). The second is that the majority of cells gave increased responses immediately after conditioning saccades in at least one direction. Receptive field shifts could evoke this consistent high-to-low response pattern only if we erroneously mapped the receptive fields of most cells, missing their most effective locations.