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Abstract:
Abstract: A distinguishing feature of smooth pursuit eye
movements is that they usually require the presence of a moving
visual target, unlike other voluntary eye movements. One notable
exception is anticipatory pursuit, where the past history of or
expectation about upcoming target motion can lead to an eye
movement before a target starts to move. Current models describe
only the visually-guided portion of the smooth pursuit movement. We
have developed a model that can trigger anticipatory pursuit based
upon the activity of neurons recorded in the supplementary eye
field (SEF) that are active in advance of target motion (Heinen and
Liu, 1997), as well as the finding that extinguishing the fixation
point before the target moves produces greater anticipatory eye
velocity (Heinen and Chaipat, 1999). In the model, an excitatory
anticipation signal and an inhibitory fixation signal are
implemented together in a push-pull arrangement. Simulations from
the model predict an optimal gap for anticipatory pursuit, and can
explain the paradoxical excitatory/inhibitory effect on pursuit
observed when stimulating certain sites in the SEF of primates
(Heinen, 1996).
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