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Roth AM, Lokesh R, Tang J, Buggeln JH, Smith C, Calalo JA, Sullivan SR, Ngo T, Germain LS, Carter MJ, Cashaback JGA. Punishment Leads to Greater Sensorimotor Learning But Less Movement Variability Compared to Reward. Neuroscience 2024; 540:12-26. [PMID: 38220127 PMCID: PMC10922623 DOI: 10.1016/j.neuroscience.2024.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 01/05/2024] [Accepted: 01/09/2024] [Indexed: 01/16/2024]
Abstract
When a musician practices a new song, hitting a correct note sounds pleasant while striking an incorrect note sounds unpleasant. Such reward and punishment feedback has been shown to differentially influence the ability to learn a new motor skill. Recent work has suggested that punishment leads to greater movement variability, which causes greater exploration and faster learning. To further test this idea, we collected 102 participants over two experiments. Unlike previous work, in Experiment 1 we found that punishment did not lead to faster learning compared to reward (n = 68), but did lead to a greater extent of learning. Surprisingly, we also found evidence to suggest that punishment led to less movement variability, which was related to the extent of learning. We then designed a second experiment that did not involve adaptation, allowing us to further isolate the influence of punishment feedback on movement variability. In Experiment 2, we again found that punishment led to significantly less movement variability compared to reward (n = 34). Collectively our results suggest that punishment feedback leads to less movement variability. Future work should investigate whether punishment feedback leads to a greater knowledge of movement variability and or increases the sensitivity of updating motor actions.
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Affiliation(s)
- Adam M Roth
- Department of Mechanical Engineering, University of Delaware, United States
| | - Rakshith Lokesh
- Department of Biomedical Engineering, University of Delaware, United States
| | - Jiaqiao Tang
- Department of Kinesiology, McMaster University, Canada
| | - John H Buggeln
- Department of Biomedical Engineering, University of Delaware, United States
| | - Carly Smith
- Department of Biomedical Engineering, University of Delaware, United States
| | - Jan A Calalo
- Department of Mechanical Engineering, University of Delaware, United States
| | - Seth R Sullivan
- Department of Biomedical Engineering, University of Delaware, United States
| | - Truc Ngo
- Department of Biomedical Engineering, University of Delaware, United States
| | | | | | - Joshua G A Cashaback
- Department of Mechanical Engineering, University of Delaware, United States; Department of Biomedical Engineering, University of Delaware, United States; Kinesiology and Applied Physiology, University of Delaware, United States; Interdisciplinary Neuroscience Graduate Program, University of Delaware, United States; Biomechanics and Movement Science Program, University of Delaware, United States; Department of Kinesiology, McMaster University, Canada.
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Roth AM, Calalo JA, Lokesh R, Sullivan SR, Grill S, Jeka JJ, van der Kooij K, Carter MJ, Cashaback JGA. Reinforcement-based processes actively regulate motor exploration along redundant solution manifolds. Proc Biol Sci 2023; 290:20231475. [PMID: 37848061 PMCID: PMC10581769 DOI: 10.1098/rspb.2023.1475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 09/06/2023] [Indexed: 10/19/2023] Open
Abstract
From a baby's babbling to a songbird practising a new tune, exploration is critical to motor learning. A hallmark of exploration is the emergence of random walk behaviour along solution manifolds, where successive motor actions are not independent but rather become serially dependent. Such exploratory random walk behaviour is ubiquitous across species' neural firing, gait patterns and reaching behaviour. The past work has suggested that exploratory random walk behaviour arises from an accumulation of movement variability and a lack of error-based corrections. Here, we test a fundamentally different idea-that reinforcement-based processes regulate random walk behaviour to promote continual motor exploration to maximize success. Across three human reaching experiments, we manipulated the size of both the visually displayed target and an unseen reward zone, as well as the probability of reinforcement feedback. Our empirical and modelling results parsimoniously support the notion that exploratory random walk behaviour emerges by utilizing knowledge of movement variability to update intended reach aim towards recently reinforced motor actions. This mechanism leads to active and continuous exploration of the solution manifold, currently thought by prominent theories to arise passively. The ability to continually explore muscle, joint and task redundant solution manifolds is beneficial while acting in uncertain environments, during motor development or when recovering from a neurological disorder to discover and learn new motor actions.
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Affiliation(s)
- Adam M. Roth
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Jan A. Calalo
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Rakshith Lokesh
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Seth R. Sullivan
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Stephen Grill
- Kinesiology and Applied Physiology, University of Delaware, Newark, DE 19716, USA
| | - John J. Jeka
- Kinesiology and Applied Physiology, University of Delaware, Newark, DE 19716, USA
- Interdisciplinary Neuroscience Graduate Program, University of Delaware, Newark, DE 19716, USA
- Biomechanics and Movement Science Program, University of Delaware, Newark, DE 19716, USA
| | - Katinka van der Kooij
- Faculty of Behavioural and Movement Science, Vrije University Amsterdam, Amsterdam, 1081HV, The Netherlands
| | - Michael J. Carter
- Department of Kinesiology, McMaster University, Room 203, Ivor Wynne Centre, Hamilton, L8S 4L8, Ontario, Canada
| | - Joshua G. A. Cashaback
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
- Kinesiology and Applied Physiology, University of Delaware, Newark, DE 19716, USA
- Interdisciplinary Neuroscience Graduate Program, University of Delaware, Newark, DE 19716, USA
- Biomechanics and Movement Science Program, University of Delaware, Newark, DE 19716, USA
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Calalo JA, Roth AM, Lokesh R, Sullivan SR, Wong JD, Semrau JA, Cashaback JGA. The sensorimotor system modulates muscular co-contraction relative to visuomotor feedback responses to regulate movement variability. J Neurophysiol 2023; 129:751-766. [PMID: 36883741 PMCID: PMC10069957 DOI: 10.1152/jn.00472.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 02/13/2023] [Accepted: 03/01/2023] [Indexed: 03/09/2023] Open
Abstract
The naturally occurring variability in our movements often poses a significant challenge when attempting to produce precise and accurate actions, which is readily evident when playing a game of darts. Two differing, yet potentially complementary, control strategies that the sensorimotor system may use to regulate movement variability are impedance control and feedback control. Greater muscular co-contraction leads to greater impedance that acts to stabilize the hand, while visuomotor feedback responses can be used to rapidly correct for unexpected deviations when reaching toward a target. Here, we examined the independent roles and potential interplay of impedance control and visuomotor feedback control when regulating movement variability. Participants were instructed to perform a precise reaching task by moving a cursor through a narrow visual channel. We manipulated cursor feedback by visually amplifying movement variability and/or delaying the visual feedback of the cursor. We found that participants decreased movement variability by increasing muscular co-contraction, aligned with an impedance control strategy. Participants displayed visuomotor feedback responses during the task but, unexpectedly, there was no modulation between conditions. However, we did find a relationship between muscular co-contraction and visuomotor feedback responses, suggesting that participants modulated impedance control relative to feedback control. Taken together, our results highlight that the sensorimotor system modulates muscular co-contraction, relative to visuomotor feedback responses, to regulate movement variability and produce accurate actions.NEW & NOTEWORTHY The sensorimotor system has the constant challenge of dealing with the naturally occurring variability in our movements. Here, we investigated the potential roles of muscular co-contraction and visuomotor feedback responses to regulate movement variability. When we visually amplified movements, we found that the sensorimotor system primarily uses muscular co-contraction to regulate movement variability. Interestingly, we found that muscular co-contraction was modulated relative to inherent visuomotor feedback responses, suggesting an interplay between impedance and feedback control.
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Affiliation(s)
- Jan A Calalo
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, United States
- Department of Mechanical Engineering, University of Delaware, Newark, Delaware, United States
| | - Adam M Roth
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, United States
- Department of Mechanical Engineering, University of Delaware, Newark, Delaware, United States
| | - Rakshith Lokesh
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, United States
| | - Seth R Sullivan
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, United States
| | - Jeremy D Wong
- Department of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biomedical Engineering, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer A Semrau
- Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
- Biomechanics and Movement Science Program, University of Delaware, Newark, Delaware, United States
- Interdisciplinary Neuroscience Graduate Program, University of Delaware, Newark, Delaware, United States
| | - Joshua G A Cashaback
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, United States
- Department of Mechanical Engineering, University of Delaware, Newark, Delaware, United States
- Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
- Biomechanics and Movement Science Program, University of Delaware, Newark, Delaware, United States
- Interdisciplinary Neuroscience Graduate Program, University of Delaware, Newark, Delaware, United States
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Dimitriou M. Human muscle spindles are wired to function as controllable signal-processing devices. eLife 2022; 11:78091. [PMID: 35829705 PMCID: PMC9278952 DOI: 10.7554/elife.78091] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/29/2022] [Indexed: 12/26/2022] Open
Abstract
Muscle spindles are encapsulated sensory organs found in most of our muscles. Prevalent models of sensorimotor control assume the role of spindles is to reliably encode limb posture and movement. Here, I argue that the traditional view of spindles is outdated. Spindle organs can be tuned by spinal γ motor neurons that receive top-down and peripheral input, including from cutaneous afferents. A new model is presented, viewing γ motor activity as an intermediate coordinate transformation that allows multimodal information to converge on spindles, creating flexible coordinate representations at the level of the peripheral nervous system. That is, I propose that spindles play a unique overarching role in the nervous system: that of a peripheral signal-processing device that flexibly facilitates sensorimotor performance, according to task characteristics. This role is compatible with previous findings and supported by recent studies with naturalistically active humans. Such studies have so far shown that spindle tuning enables the independent preparatory control of reflex muscle stiffness, the selective extraction of information during implicit motor adaptation, and for segmental stretch reflexes to operate in joint space. Incorporation of advanced signal-processing at the periphery may well prove a critical step in the evolution of sensorimotor control theories.
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Affiliation(s)
- Michael Dimitriou
- Physiology Section, Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
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Sutter K, Oostwoud Wijdenes L, van Beers RJ, Medendorp WP. Even well-practiced movements benefit from repetition. J Neurophysiol 2022; 127:1407-1416. [PMID: 35443142 DOI: 10.1152/jn.00003.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Professional golf players spend years practicing, but will still perform one or two practice swings without a ball before executing the actual swing. Why do they do this? In this study we tested the hypothesis that repeating a well-practiced movement leads to a reduction of movement variability. To operationalize this hypothesis, participants were tested in a center-out reaching task with four different targets, on four different days. To probe the effect of repetition they performed random sequences from one to six movements to the same target. Our findings show that, with repetition, movements are not only initiated earlier but their variability is reduced across the entire movement trajectory. Furthermore, this effect is present within and across the four sessions. Together, our results suggest that movement repetition changes the tradeoff between movement initiation and movement precision.
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Affiliation(s)
- Katrin Sutter
- Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Leonie Oostwoud Wijdenes
- Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Robert J van Beers
- Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.,Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - W Pieter Medendorp
- Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
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