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Billen LS, Corneil BD, Weerdesteyn V. Evidence for an Intricate Relationship Between Express Visuomotor Responses, Postural Control and Rapid Step Initiation in the Lower Limbs. Neuroscience 2023; 531:60-74. [PMID: 37709004 DOI: 10.1016/j.neuroscience.2023.07.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 09/16/2023]
Abstract
Recent work has described express visuomotor responses (EVRs) on the upper limb. EVRs are directionally-tuned bursts of muscle activity that occur within 100 ms of visual stimulus appearance, facilitating rapid reaching. Rapid stepping responses are also important in daily life, and while there is evidence of EVR expression on lower limbs, it is unknown whether lower-limb EVRs are influenced by increased postural demands. Here, we investigate the interaction between stepping-related EVRs and anticipatory postural adjustments (APAs) that typically precede step initiation. 16 healthy young subjects rapidly stepped towards visual targets presented in front of the left or right foot. We recorded bilateral surface EMG of gluteus medius (GM), a muscle involved in both APAs and stepping, and bilateral ground reaction forces. Two conditions were introduced: an anterolateral or anteromedial stepping condition with reduced or increased postural demands, respectively. In the anterolateral stepping condition, EVRs were robustly and strongly present in stance-side GM, and ground reaction forces revealed strongly decreased expression of APAs. Larger EVRs preceded shorter RTs, consistent with EVRs facilitating step initiation. In contrast, in the anteromedial stepping condition, EVRs were largely absent, and ground reaction forces revealed the consistent expression of APAs. When occasionally present, EVRs in the anteromedial stepping condition preceded larger APAs and longer RTs. Thus, while EVRs in lower limbs can facilitate rapid stepping, their expression is normally suppressed when postural stability is low. Failing to appropriately suppress EVRs in such situations disrupts postural stability, necessitating larger compensatory APAs and leading to longer stepping RTs.
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Affiliation(s)
- Lucas S Billen
- Department of Rehabilitation - Donders Institute for Brain, Cognition & Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Brian D Corneil
- Department of Physiology & Pharmacology, Western University, London, Canada; Robarts Research Institute, London, Canada
| | - Vivian Weerdesteyn
- Department of Rehabilitation - Donders Institute for Brain, Cognition & Behavior, Radboud University Medical Center, Nijmegen, The Netherlands; Sint Maartenskliniek Research, Nijmegen, The Netherlands
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Contemori S, Loeb GE, Corneil BD, Wallis G, Carroll TJ. Express Visuomotor Responses Reflect Knowledge of Both Target Locations and Contextual Rules during Reaches of Different Amplitudes. J Neurosci 2023; 43:7041-7055. [PMID: 37714709 PMCID: PMC10586536 DOI: 10.1523/jneurosci.2069-22.2023] [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: 11/06/2022] [Revised: 07/24/2023] [Accepted: 08/31/2023] [Indexed: 09/17/2023] Open
Abstract
When humans reach to visual targets, extremely rapid (∼90 ms) target-directed responses can be observed in task-relevant proximal muscles. Such express visuomotor responses are inflexibly locked in time and space to the target and have been proposed to reflect rapid visuomotor transformations conveyed subcortically via the tecto-reticulo-spinal pathway. Previously, we showed that express visuomotor responses are sensitive to explicit cue-driven information about the target, suggesting that the express pathway can be modulated by cortical signals affording contextual prestimulus expectations. Here, we show that the express visuomotor system incorporates information about the physical hand-to-target distance and contextual rules during visuospatial tasks requiring different movement amplitudes. In one experiment, we recorded the activity from two shoulder muscles as 14 participants (6 females) reached toward targets that appeared at different distances from the reaching hand. Increasing the reaching distance facilitated the generation of frequent and large express visuomotor responses. This suggests that both the direction and amplitude of veridical hand-to-target reaches are encoded along the putative subcortical express pathway. In a second experiment, we modulated the movement amplitude by asking 12 participants (4 females) to deliberately undershoot, overshoot, or stop (control) at the target. The overshoot and undershoot tasks impaired the generation of large and frequent express visuomotor responses, consistent with the inability of the express pathway to generate responses directed toward nonveridical targets as in the anti-reach task. Our findings appear to reflect strategic, cortically driven modulation of the express visuomotor circuit to facilitate rapid and effective response initiation during target-directed actions.SIGNIFICANCE STATEMENT Express (∼90 ms) arm muscle responses that are consistently tuned toward the location of visual stimuli suggest a subcortical contribution to target-directed visuomotor behavior in humans, potentially via the tecto-reticulo-spinal pathway. Here, we show that express muscle responses are modulated appropriately to reach targets at different distances, but generally suppressed when the task required nonveridical responses to overshoot/undershoot the real target. This suggests that the tecto-reticulo-spinal pathway can be exploited strategically by the cerebral cortex to facilitate rapid initiation of effective responses during a visuospatial task.
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Affiliation(s)
- Samuele Contemori
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Human Movement Studies Building, University of Queensland, Brisbane, 4067 Queensland, Australia
| | - Gerald E Loeb
- Alfred E. Mann Department of Biomedical Engineering, University of Southern California-Los Angeles, Los Angeles, California 90089-1112
| | - Brian D Corneil
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Department of Psychology, Western University, London, Ontario N6A 5C2, Canada
- Robarts Research Institute, London, Ontario N6A 3K7, Canada
| | - Guy Wallis
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Human Movement Studies Building, University of Queensland, Brisbane, 4067 Queensland, Australia
| | - Timothy J Carroll
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Human Movement Studies Building, University of Queensland, Brisbane, 4067 Queensland, Australia
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Cecala AL, Kozak RA, Pruszynski JA, Corneil BD. Done in 65 ms: Express Visuomotor Responses in Upper Limb Muscles in Rhesus Macaques. eNeuro 2023; 10:ENEURO.0078-23.2023. [PMID: 37507227 PMCID: PMC10449271 DOI: 10.1523/eneuro.0078-23.2023] [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: 03/07/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
How rapidly can the brain transform vision into action? Work in humans has established that the transformation for visually-guided reaching can be remarkably rapid, with the first phase of upper limb muscle recruitment, the express visuomotor response, beginning within less than 100 ms of visual target presentation. Such short-latency responses limit the opportunities for extensive cortical processing, leading to the hypothesis that they are generated via the subcortical tecto-reticulo-spinal pathway. Here, we examine whether nonhuman primates (NHPs) exhibit express visuomotor responses. Two male macaques made visually-guided reaches in a behavioral paradigm known to elicit express visuomotor responses in humans, while we acquired intramuscular recordings from the deltoid muscle. Across several variants of this paradigm, express visuomotor responses began within 65 ms (range: 48-91 ms) of target presentation. Although the timing of the express visuomotor response did not co-vary with reaction time, larger express visuomotor responses tended to precede shorter latency reaches. Further, we observed that the magnitude of the express visuomotor response could be muted by contextual context, although this effect was quite variable. Overall, the response properties in NHPs resemble those in humans. Our results establish a new benchmark for visuomotor transformations underlying visually-guided reaches, setting the stage for experiments that can directly compare the role of cortical and subcortical areas in reaching when time is of the essence.
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Affiliation(s)
- Aaron L Cecala
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5B7, Canada
- Robarts Research Institute, London, Ontario N6A 5B7, Canada
| | - Rebecca A Kozak
- Graduate Program in Neuroscience, Western University, London, Ontario N6A 5B7, Canada
| | - J Andrew Pruszynski
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5B7, Canada
- Robarts Research Institute, London, Ontario N6A 5B7, Canada
| | - Brian D Corneil
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5B7, Canada
- Robarts Research Institute, London, Ontario N6A 5B7, Canada
- Department of Psychology, Western University, London, Ontario N6A 5B7, Canada
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Selen LPJ, Corneil BD, Medendorp WP. Single-Trial Dynamics of Competing Reach Plans in the Human Motor Periphery. J Neurosci 2023; 43:2782-2793. [PMID: 36898839 PMCID: PMC10089241 DOI: 10.1523/jneurosci.1640-22.2023] [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: 08/29/2022] [Revised: 01/31/2023] [Accepted: 02/08/2023] [Indexed: 03/12/2023] Open
Abstract
Contemporary motor control theories propose competition between multiple motor plans before the winning command is executed. While most competitions are completed before movement onset, movements are often initiated before the competition has been resolved. An example of this is saccadic averaging, wherein the eyes land at an intermediate location between two visual targets. Behavioral and neurophysiological signatures of competing motor commands have also been reported for reaching movements, but debate remains about whether such signatures attest to an unresolved competition, arise from averaging across many trials, or reflect a strategy to optimize behavior given task constraints. Here, we recorded EMG activity from an upper limb muscle (m. pectoralis) while 12 (8 female) participants performed an immediate response reach task, freely choosing between one of two identical and suddenly presented visual targets. On each trial, muscle recruitment showed two distinct phases of directionally tuned activity. In the first wave, time-locked ∼100 ms of target presentation, muscle activity was clearly influenced by the nonchosen target, reflecting a competition between reach commands that was biased in favor of the ultimately chosen target. This resulted in an initial movement intermediate between the two targets. In contrast, the second wave, time-locked to voluntary reach onset, was not biased toward the nonchosen target, showing that the competition between targets was resolved. Instead, this wave of activity compensated for the averaging induced by the first wave. Thus, single-trial analysis reveals an evolution in how the nonchosen target differentially influences the first and second wave of muscle activity.SIGNIFICANCE STATEMENT Contemporary theories of motor control suggest that multiple motor plans compete for selection before the winning command is executed. Evidence for this is found in intermediate reach movements toward two potential target locations, but recent findings have challenged this notion by arguing that intermediate reaching movements reflect an optimal response strategy. By examining upper limb muscle recruitment during a free-choice reach task, we show early recruitment of a suboptimal averaged motor command to the two targets that subsequently transitions to a single motor command that compensates for the initially averaged motor command. Recording limb muscle activity permits single-trial resolution of the dynamic influence of the nonchosen target through time.
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Affiliation(s)
- Luc P J Selen
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, 6500 HB, The Netherlands
| | - Brian D Corneil
- Department of Physiology and Pharmacology
- Department of Psychology, Western University, London, Ontario N6A 5B7, Canada
- Robarts Research Institute, London, Ontario, Canada, N6A 5B7
| | - W Pieter Medendorp
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, 6500 HB, The Netherlands
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Contemori S, Loeb GE, Corneil BD, Wallis G, Carroll TJ. Symbolic cues enhance express visuomotor responses in human arm muscles at the motor planning rather than the visuospatial processing stage. J Neurophysiol 2022; 128:494-510. [PMID: 35858112 DOI: 10.1152/jn.00136.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Humans can produce "express" (~100ms) arm muscle responses that are inflexibly locked in time and space to visual target presentations, consistent with subcortical visuomotor transformations via the tecto-reticulo-spinal pathway. These express visuomotor responses are sensitive to explicit cue-driven expectations, but it is unclear at what stage of sensory-to-motor transformation such modulation occurs. Here, we recorded electromyographic activity from shoulder muscles as participants reached toward one of four virtual targets whose physical location was partially predictable from a symbolic cue. In an experiment in which targets could be veridically reached, express responses were inclusive of the biomechanical requirements for reaching the cued locations and not systematically modulated by cue validity. In a second experiment, movements were restricted to the horizontal plane so that the participants could perform only rightward or leftward reaches, irrespective of target position on the vertical axis. Express muscle responses were almost identical for targets that were validly cued in the horizontal direction, regardless of cue validity in the vertical dimension. Together, these findings suggest that the cue-induced enhancements of express responses are dominated by effects at the level of motor plans and not solely via facilitation of early visuospatial target processing. Notably, direct cortico-tectal and cortico-reticular projections exist that are well-placed to modulate pre-stimulus motor preparation state in subcortical circuits. Our results could reflect a neural mechanism by which contextually relevant motor responses to compatible visual inputs are rapidly released via subcortical circuits that are sufficiently along the sensory- to-motor continuum.
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Affiliation(s)
- Samuele Contemori
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
| | - Gerald E Loeb
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - Brian D Corneil
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.,Department of Psychology, Western University, London, Ontario, Canada.,Robarts Research Institute, London, Ontario, Canada
| | - Guy Wallis
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
| | - Timothy J Carroll
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
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Kearsley SL, Cecala AL, Kozak RA, Corneil BD. Express arm responses appear bilaterally on upper-limb muscles in an arm choice reaching task. J Neurophysiol 2022; 127:969-983. [PMID: 35294268 DOI: 10.1152/jn.00494.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
When required, humans can generate very short latency reaches toward visual targets, such as catching a falling cellphone. During such rapid reaches, express arm responses are the first wave of upper limb muscle recruitment, occurring ∼80-100 ms after target appearance. There is accumulating evidence that express arm responses arise from signaling along the tecto-reticulo-spinal tract, but the involvement of the reticulospinal tract has not been well studied. Since the reticulospinal tract projects bilaterally, we studied whether express arm responses would be generated bilaterally. Human participants (n = 14; 7 females) performed visually guided reaches in a modified emerging target paradigm where either arm could intercept the target. We recorded electromyographic activity bilaterally from the pectoralis major muscle. Our analysis focused on target locations where participants reached with the right arm on some trials, and the left arm on others. In support of the involvement of the reticulospinal tract, express arm responses persisted bilaterally regardless of which arm reached to the target. The latency and magnitude of the express arm response did not depend on whether the arm was chosen to reach or not. However, on the reaching arm, the magnitude of the express arm response was correlated to the level of anticipatory activity. The bilateral generation of express arm responses supports the involvement of the reticulospinal tract. We surmise that the correlation between anticipatory activity and the magnitude of express arm responses on the reaching arm arises from convergence of cortically derived signals with a parallel subcortical pathway mediating the express arm response.NEW & NOTEWORTHY Express arm responses have been proposed to arise from the tecto-reticulo-spinal tract originating within the superior colliculus, but the involvement of the reticulospinal tract has not been well studied. Here, we show these responses appear bilaterally in a task where either arm can reach to a newly appearing stimulus. Our results suggest that the most rapid visuomotor transformations for reaching are performed by a subcortical pathway.
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Affiliation(s)
- Sarah L Kearsley
- Graduate Program in Neuroscience, Western University, London, Ontario, Canada.,Robarts Research Institute, Western University, London, Ontario, Canada
| | - Aaron L Cecala
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.,Robarts Research Institute, Western University, London, Ontario, Canada
| | - Rebecca A Kozak
- Graduate Program in Neuroscience, Western University, London, Ontario, Canada.,Robarts Research Institute, Western University, London, Ontario, Canada
| | - Brian D Corneil
- Graduate Program in Neuroscience, Western University, London, Ontario, Canada.,Department of Psychology, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.,Robarts Research Institute, Western University, London, Ontario, Canada
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