Reach adaptation and proprioceptive recalibration following terminal visual feedback of the hand

Abstract

We have shown that when subjects reach with continuous, misaligned visual feedback of their hand, their reaches are adapted and proprioceptive sense of hand position is recalibrated to partially match the visual feedback (Salomonczyk et al., 2011). It is unclear if similar changes arise after reaching with visual feedback that is provided only at the end of the reach (i.e., terminal feedback), when there are shorter temporal intervals for subjects to experience concurrent visual and proprioceptive feedback. Subjects reached to targets with an aligned hand-cursor that provided visual feedback at the end of each reach movement across a 99-trial training block, and with a rotated cursor over three successive blocks of 99 trials each. After each block, no cursor reaches, to measure aftereffects, and felt hand positions were measured. Felt hand position was determined by having subjects indicate the position of their unseen hand relative to a reference marker. We found that subjects adapted their reaches following training with rotated terminal visual feedback, yet slightly less (i.e., reach aftereffects were smaller), than subjects from a previous study who experienced continuous visual feedback. Nonetheless, current subjects recalibrated their sense of felt hand position in the direction of the altered visual feedback, but this proprioceptive change increased incrementally over the three rotated training blocks. Final proprioceptive recalibration levels were comparable to our previous studies in which subjects performed the same task with continuous visual feedback. Thus, compared to reach training with continuous, but altered visual feedback, subjects who received terminal altered visual feedback of the hand produced significant but smaller reach aftereffects and similar changes in hand proprioception when given extra training. Taken together, results suggest that terminal feedback of the hand is sufficient to drive motor adaptation, and also proprioceptive recalibration.

Visual and proprioceptive recalibrations after exposure to a visuomotor rotation

“…The procedures used in the present study to assess proprioceptive and visual recalibration were different from various other procedures reported in the literature (e.g., Barkley et al., ; Cameron, Franks, Inglis, & Chua, ; Clayton et al., ; Cressman & Henriques, , ; Cressman, Salomonczyk, & Henriques, ; Izawa et al., ; Mostafa et al., , ; Nourouzpour et al., ; Salomonczyk et al., ; Simani et al., ; Synofzik et al., ; Van Beers et al., ; Zbib et al., ). Namely, our participants matched the perceived position of the exposed hand at the end of a center‐out movement (as a stimulus to be judged) by the position of the exposed hand on a circular path (as a reference).…”

“…The violation is known as the “El Greco fallacy” (Firestone, ), and the principle holds that the perceived position of the exposed hand should be compared with a neutral reference, that is, the perceived position of something (non‐exposed hand, visual stimulus, body midline, etc.) that is not affected by adaptation (e.g., Barkley, Salomonczyk, Cressman, & Henriques, ; Clayton et al., ; Cressman & Henriques, , ; Izawa, Criscimagna‐Hemminger, & Shadmehr, ; Mostafa, Kamran‐Disfani, Bahari‐Kashani, Cressman, & Henriques, ; Mostafa et al., ; Nourouzpour et al., ; Salomonczyk, Cressman, & Henriques, ; Simani et al., ; Synofzik et al., ; Van Beers et al., ; Zbib et al., ). As soon as the putative neutral reference is not neutral but also recalibrated, the procedures should fail to identify proprioceptive recalibration.…”

The effect of age on visuomotor learning processes

“…Adaptation leads not only to implicit motor changes that persist even when the perturbation is removed, but also changes in proprioceptive estimates of hand location. Proprioceptive estimates of hand position have been robustly shown to shift, or be recalibrated, following both visuomotor adaptation [15, [32][33][34][35][36][37][38] and force field adaptation [39,40]. In the case of visuomotor adaptation, estimates of the unseen hand's location shift in the direction of the visual representation of the hand during training, usually bỹ 20% of the visuomotor distortion [15,[32][33][34][35][36][37]41].…”

“…Proprioceptive estimates of hand position have been robustly shown to shift, or be recalibrated, following both visuomotor adaptation [15, [32][33][34][35][36][37][38] and force field adaptation [39,40]. In the case of visuomotor adaptation, estimates of the unseen hand's location shift in the direction of the visual representation of the hand during training, usually bỹ 20% of the visuomotor distortion [15,[32][33][34][35][36][37]41]. In turn, this visually-induced change in hand proprioception appears to contribute to changes in motor performance, particularly reach aftereffects [13, [42][43][44][45].…”

Visuomotor learning is dependent on direction-specific error saliency

“…Previous studies have established that uncertainty of error feedback slows down adaptation (Burge et al 2008;He et al 2016;Körding and Wolpert 2004;Wei and Körding 2010). In contrast, providing more sensory feedback with continuous cursor display, as compared with intermittent display at the end of the movement, would lead to more adaptation (Barkley et al 2014) and generalization (Shabbott and Sainburg 2010). Thus visuomotor adaptation and generalization are sensitive to the quality of visual errors, and this type of error-based learning is closely related to the cerebellum (Shadmehr 2004).…”