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Mineo Takagi, Haruki Abe, Shigeru Hasegawa, Tomoaki Usui, Hiruma Hasebe, Atsushi Miki, David S. Zee; Context-Specific Adaptation of Pursuit Initiation in Humans. Invest. Ophthalmol. Vis. Sci. 2000;41(12):3763-3769.
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purpose. To determine if multiple states for the initiation of pursuit, as
assessed by acceleration in the “open-loop” period, can be learned
and gated by context.
methods. Four normal subjects were studied. A modified step-ramp paradigm for
horizontal pursuit was used to induce adaptation. In an increasing paradigm, target velocity doubled 230 msec
after onset; in a decreasing paradigm, it was halved. In
the first experiment, vertical eye position (±5°) was used as the
context cue, and the training paradigm (increasing or decreasing)
changed with vertical eye position. In the second experiment, with
vertical position constant, when the target was red, training was
decreasing, and when green, increasing. The average eye acceleration in
the first 100 msec of tracking was the index of open-loop pursuit
results. With vertical position as the cue, pursuit adaptation differed between
up and down gaze. In some cases, the direction of adaptation was in
exact accord with the training stimuli. In others, acceleration
increased or decreased for both up and down gaze but always in correct
relative proportion to the training stimuli. In contrast, multiple
adaptive states were not induced with color as the cue.
conclusions. Multiple values for the relationship between the average eye
acceleration during the initiation of pursuit and target velocity could
be learned and gated by context. Vertical position was an effective
contextual cue but not target color, implying that useful contextual
cues must be similar to those occurring naturally, for example, orbital
position with eye muscle weakness.
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