Context-specific adaptation of saccade gain is enhanced with rest intervals between changes in context state.
Dual-state adaptation of motor responses has been known for some time. A more recent development is a form of dual-state adaptation known as "context-specific adaptation," which was explored through the use of saccade gain adaptation. In this model, two different adapted saccade gains are associated with two different states of a context cue, and the gain switches between the two adapted states when the context cue changes state. Such adaptation is imposed by alternating context/adaptation states over the course of an adaptation session. Here, vertical eye position as a context cue for adaptation of horizontal saccade gain is used: gain increase is induced with the eyes up 10 degrees, and gain decrease with the eyes down 10 degrees. This context cue is not very effective: there is interference between context/adaptation conditions such that gain-decrease adaptation with eyes down transfers to the eyes-up (gain-increase) context. It was hypothesized that the juxtaposition in time of the alternating adaptation states exacerbated this interference. In order to test this, one-minute rest breaks were inserted between each change in context/adaptation state. The resulting context-specific adaptation improved dramatically: gain-increase and gain-decrease adaptations were more rapid and more complete. This resembles consolidation of motor learning, which, however, occurs over much longer time spans (hours rather than minutes). Thus, the results may reflect the operation of a novel "short-term" motor consolidation process.
Shelhamer, M; Aboukhalil, A; Clendaniel, R
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