Asymmetry in kinematic generalization between visual and passive lead-in movements are consistent with a forward model in the sensorimotor system

2022

PLoS Comput Biol

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The separation of distinct motor memories by contextual cues is a well known and well studied phenomenon of feedforward human motor control. However, there is no clear evidence of such context-induced separation in feedback control. Here we test both experimentally and computationally if context-dependent switching of feedback controllers is possible in the human motor system. Specifically, we probe visuomotor feedback responses of our human participants in two different tasks—stop and hit—and under two different schedules. The first, blocked schedule, is used to measure the behaviour of stop and hit controllers in isolation, showing that it can only be described by two independent controllers with two different sets of control gains. The second, mixed schedule, is then used to compare how such behaviour evolves when participants regularly switch from one task to the other. Our results support our hypothesis that there is contextual switching of feedback controllers, further extending the accumulating evidence of shared features between feedforward and feedback control.

Section: Discussionmentioning

confidence: 99%

Contextual cues are not unique for motor learning: Task-dependant switching of feedback controllers

Česonis

2022

PLoS Comput Biol

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“…It has been shown that our planned trajectory is based on the visual geometric information of the entire system, not just the endpoint, by using a novel mapping between finger movements and the object movement (Danziger and Mussa-Ivaldi 2012). In terms of adapting simultaneously to two opposing force fields, certain types of visual feedback can be used as a contextual cue to separate the learning of these dynamics (Forano et al 2021; Howard et al 2020; Howard et al 2012; Howard et al 2013; Howard et al 2015). The fact that only specific types of contextual information allows the learning of two opposing force fields, suggests that only specific signals trigger a switch between or access specific motor memories in a given task.…”

Section: Discussionmentioning

confidence: 99%

“…Further studies would be needed to confirm whether these visual cues are used within state estimation as we suggest with our model. One possible test of this would be to investigate the role of these online visual cues in dual adaptation paradigms (Howard et al 2013) as we have suggested that strength of contextual cues depends on their use within state estimation (Forano et al 2021; Howard and Franklin 2016; 2015; Howard et al 2020; Howard et al 2012). While we can only speculate on the mechanism which drives this increase in adaptation, it is clear that congruent visual cues increase the adaptation to novel dynamics compared with either incongruent or the absence of visual cues.…”

Section: Discussionmentioning

confidence: 99%

“…In terms of adapting simultaneously to two opposing force fields, certain types of visual feedback can be used as a contextual cue to separate the learning of these dynamics (Forano et al 2021;Howard et al 2020;Howard et al 2012;Howard et al 2013;. The fact that only specific types of contextual information allows the learning of two opposing force fields, suggests that only specific signals trigger a switch between or access specific motor memories in a given task.…”

Section: Discussionmentioning

confidence: 99%

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Congruent visual cues speed dynamic motor adaptation

Leib

Dimitriou

et al. 2023

Preprint

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Motor adaptation to novel dynamics occurs rapidly using sensed errors to update the current motor memory. This adaption is strongly driven by proprioceptive and visual signals, that indicate errors in the motor memory. Here we extend this previous work by investigating whether the presence of additional visual cues could increase the rate of motor adaptation, specifically when the visual motion cue is congruent with the dynamics. Six groups of participants performed reaching movements while grasping the handle of a robotic manipulandum while an additional cue (red object) was connected to the cursor. After a baseline, either a unidirectional (3 groups) or bidirectional (3 groups) velocity dependent force field was applied during the reach. For each group, the movement of the red object relative to the cursor was either congruent with the force field dynamics, incongruent with the force field dynamics or constant (fixed distance). Participants adapted more to the unidirectional force fields than to the bidirectional force field groups. However, across both force fields, groups in which the visual cues matched the type of force field (congruent visual cue) exhibited higher final adaptation level at the end of learning compared to either the control or incongruent conditions. In all groups, we observed an additional congruent cue assisted the formation of the motor memory of the external dynamics. We then demonstrate that a state estimation based model that integrates proprioceptive and visual information can successfully replicate the experimental data.

“…Such adaptation can be examined using a dual-adaptation paradigm in which participants adapt simultaneously to two different dynamics, each signalled by a contextual cue.When appropriate contextual cues are provided, humans are able to select, recall and adapt the respective model memory for each task [38][39][40][41][42][43][44][45][46]. Dual-adaptation has been shown to occur when the contextual cue is different in the physical or visual hand state [42,43], workspace visual location [43,47], bimanual or unimanual arm movements [40,48], some body postures [49] or for lead-in or follow-through movements [41,[50][51][52]. In contrast, other cues such as color provides only a weak or ineffective contextual cue for dual-adaptation [43,53], despite some studies showing a small effect [54-56].…”

mentioning

confidence: 99%

Reward actively engages both implicit and explicit components in dual force field adaptation

Forano¹,

2023

Preprint

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Motor learning occurs through multiple mechanisms, including unsupervised, supervised (error-based) and reinforcement (reward-based) learning. Although studies have shown that reward leads to an overall better motor adaptation, the specific processes by which reward influences adaptation are still unclear. Here, we examine how the presence of reward affects dual-adaptation to novel dynamics, and distinguish its influence on implicit and explicit learning. Participants adapted to two opposing force fields in an adaptation/de-adaptation/error-clamp paradigm, where five levels of reward (a score and a digital face) were provided as participants reduced their lateral error. Both reward and control (no reward provided) groups simultaneously adapted to both opposing force fields, exhibiting a similar final level of adaptation, which was primarily implicit. Triple-rate models fit to the adaptation process found higher learning rates in the fast and slow processes, and a slightly increased fast retention rate for the reward group. While differences in the slow learning rate were only driven by implicit learning, the large difference in the fast learning rate was mainly explicit. Overall, we confirm previous work showing that reward increases learning rates, extending this to dual-adaptation experiments, and demonstrating that reward influences both implicit and explicit adaptation. Specifically, we show that reward acts primarily explicitly on the fast learning rate and implicitly on the slow learning rates.