Retention of visuo-proprioceptive recalibration in estimating hand position

The role of feedback in responding to gradual and abrupt visuo-proprioceptive cue conflict

When people observe conflicting visual and proprioceptive cues about their static hand position, visuo-proprioceptive recalibration results. Recalibration also occurs during gradual or abrupt visuomotor adaptation, in response to both the cue conflict and sensory prediction errors experienced as the hand reaches to a target. Here we asked whether creating a cue conflict gradually vs. abruptly, or providing error feedback, affects recalibration in a static hand. We examined participants' responses to a 70 mm visuo-proprioceptive conflict, imposed by shifting the visual cue forward from the proprioceptive cue (static left hand). Participants pointed with their unseen right hand to indicate perceived bimodal and unimodal cue positions. Conflict was introduced gradually (groups 1 and 2) or abruptly (groups 3 and 4), with performance feedback present (groups 2 and 4) or absent (groups 1 and 3). For abrupt groups, most behavioral change occurred immediately after the conflict began. No-feedback groups (1 and 3) showed comparable magnitudes of overall recalibration, indicating that abrupt and gradual conflicts result in similar recalibration but with different timings. Motor adaptation was evident in the indicator hand with performance feedback (groups 2 and 4). However, performance on a static ruler task suggests proprioceptive recalibration also occurred despite the presence of feedback. Control groups confirmed accurate performance on the pointing task despite the visual cue shift. These findings highlight the distinct timing of recalibration mechanisms for gradual versus abrupt cue conflicts and potential smaller contribution of error mechanisms for a static conflict.

The role of explicit knowledge in compensating for a visuo-proprioceptive cue conflict

It is unclear how explicit knowledge of an externally imposed mismatch between visual and proprioceptive cues of hand position affects perceptual recalibration. The Bayesian causal inference framework might suggest such knowledge should abolish the visual and proprioceptive recalibration that occurs when individuals perceive these cues as coming from the same source (their hand), while the visuomotor adaptation literature suggests explicit knowledge of a cue conflict does not eliminate implicit compensatory processes. Here we compared visual and proprioceptive recalibration in three groups with varying levels of knowledge about the visuo-proprioceptive cue conflict. All participants estimated the position of visual, proprioceptive, or combined targets related to their left index fingertip, with a 70 mm visuo-proprioceptive offset gradually imposed. Groups 1, 2, and 3 received no information, medium information, and high information, respectively, about the offset. Information was manipulated using instructional and visual cues. All groups performed the task similarly at baseline in terms of variance, weighting, and integration. Results suggest the three groups recalibrated vision and proprioception differently, but there was no difference in variance or weighting. Participants who received only instructional cues about the mismatch (Group 2) did not recalibrate less, on average, than participants provided no information about the mismatch (Group 1). However, participants provided instructional cues and extra visual cues of their hands during the perturbation (Group 3) demonstrated significantly less recalibration than other groups. These findings are consistent with the idea that instructional cues alone are insufficient to override participants' intrinsic belief in common cause and reduce recalibration.

NSF DARE-transforming modeling in neurorehabilitation: a patient-in-the-loop framework

In 2023, the National Science Foundation (NSF) and the National Institute of Health (NIH) brought together engineers, scientists, and clinicians by sponsoring a conference on computational modelling in neurorehabiilitation. To facilitate multidisciplinary collaborations and improve patient care, in this perspective piece we identify where and how computational modelling can support neurorehabilitation. To address the where, we developed a patient-in-the-loop framework that uses multiple and/or continual measurements to update diagnostic and treatment model parameters, treatment type, and treatment prescription, with the goal of maximizing clinically-relevant functional outcomes. This patient-in-the-loop framework has several key features: (i) it includes diagnostic and treatment models, (ii) it is clinically-grounded with the International Classification of Functioning, Disability and Health (ICF) and patient involvement, (iii) it uses multiple or continual data measurements over time, and (iv) it is applicable to a range of neurological and neurodevelopmental conditions. To address the how, we identify state-of-the-art and highlight promising avenues of future research across the realms of sensorimotor adaptation, neuroplasticity, musculoskeletal, and sensory & pain computational modelling. We also discuss both the importance of and how to perform model validation, as well as challenges to overcome when implementing computational models within a clinical setting. The patient-in-the-loop approach offers a unifying framework to guide multidisciplinary collaboration between computational and clinical stakeholders in the field of neurorehabilitation.

Effect of visuo-proprioceptive mismatch rate on recalibration in hand perception

We estimate our hand's position by combining relevant visual and proprioceptive cues. A cross-sensory spatial mismatch can be created by viewing the hand through a prism or, more recently, rotating a visual cursor that represents hand position. This is often done in the context of target-directed reaching to study motor adaptation, the systematic updating of motor commands in response to a systematic movement error. However, a visuo-proprioceptive mismatch also elicits recalibration in the relationship between the hand's seen and felt position. The principles governing visuo-proprioceptive recalibration are poorly understood, compared to motor adaptation. For example, motor adaptation occurs robustly whether the cursor is rotated quickly or slowly, although the former may involve more explicit processes. Here, we asked whether visuo-proprioceptive recalibration, in the absence of motor adaptation, works the same way. Three groups experienced a 70 mm visuo-proprioceptive mismatch about their hand at a Slow, Medium, or Fast rate (0.84, 1.67, or 3.34 mm every two trials, respectively), with no error feedback. Once attained, the 70 mm mismatch was maintained for the remaining trials. Total recalibration differed significantly across groups, with the Fast, Medium, and Slow groups recalibrating 63.7, 56.3, and 42.8 mm on average, respectively. This suggests a slower mismatch rate may be less effective at eliciting recalibration. In contrast to motor adaptation studies, no further recalibration was observed in the maintenance phase. This may be related to the distinct mechanisms thought to contribute to perceptual recalibration via cross-sensory cue conflict versus sensory prediction errors.