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Abstract:
Abstract: Human smooth pursuit depends upon cognitive factors
such as those related to memory of previous target motion and
cue-based expectations about upcoming target motion. These factors
enable and shape the anticipatory smooth eye movements that precede
target motion. Most studies of the neural mechanisms that guide
human smooth pursuit have been done using monkeys, yet anticipatory
pursuit in these animals has not been demonstrated. Here we show
that monkeys do in fact anticipate, and that previous target motion
influences the magnitude of anticipatory eye velocity.
Specifically, a longer sequence of prior target motions in a given
direction results in greater anticipatory eye velocity.
Interestingly, the anticipatory influence persists during the
initiation phase of pursuit, a phase which is generally considered
to be visually-guided. Furthermore, removing the visual fixation
point for a brief period before the target appears facilitates
anticipatory pursuit in a fashion similar to that observed in
humans. The results suggest that monkey and human anticipatory
pursuit are dependent upon similar stimulus contingencies, and that
anticipatory pursuit in part is driven by the release of a fixation
mechanism. We introduce a model of anticipatory pursuit based on a
push-pull interaction between these anticipation and fixation
signals.
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