Proprioception and the production of adaptation and intermanual transfer to prismatic displacement

Abstract

Proprioceptive adaptation to prismatic displacement and resultant intermanual transfer were investigated in two experiments. In Experiment 1, magnitude of adaptation and transfer were assessed as a result of the reduction of felt sensation via hypnotic anesthesia in an adapting limb. Such anesthesia reduced the magnitude of adaptation in that limb and resultant transfer in the nonadapting limb to a nonsignificant level. Such was not the case when the adapting limb was nonanesthetic. In Experiment 2, adaptation and transfer magnitude were assessed as the result of anesthetic induction in a nonadapting limb. When this was the case, adaptation was produced in the adapting limb but not in the anesthetized, nonadapting limb. The results of the two experiments generally point to proprioception as being the major source of input to the production of intermanual transfer in a prismatic adaptation task. 113 When subjects adapt to a prismatically displaced environment, a portion of the adaptation magnitude is represented by a component responsible for felt limb location or orientation (Harris, 1963, 1965; Hay & Pick, 1966; Redding, 1978; Redding & Wallace, 1976, 1978; Wallace, 1977; Wallace & Redding, 1979; Wilkinson, 1971). This adaptation component is gen­ erally assessed in a head-hand coordination task where subjects are required to localize the straight­ ahead position in space with an unseen limb before and after an exposure to prismatic displacement. The preexposure-postexposure localization difference value is termed a proprioceptive shift (PS) and post­ exposurepointing is typically in the direction opposite the exposure, prism-base orientation (Harris, 1965; Welch, 1974, 1978). Recently, it has been shown that PS is amenable to intermanual transfer (Choe & Welch, 1974; McLaughlin & Bower, 1965; Wallace, 1978; Wallace & Redding 1979; Melamed, Beckett, & Hill, Note 1). Specifically, PS can be measured for a nonadapting limb as well as for an adapting limb. As such, the recalibrated proprioceptive input appears to influence control of the unexposed limb. The experimental paradigm which appears to max­ imize intermanual transfer involves a situation where a subject is required to observe a limb perform a terminal, ballistic movement while being permitted some head movement to observe the pointing action (Wallace, 1978; Wallace & Redding, 1979). Terminal,