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1
Yokoi, Atsushi, Wenjun Bai, and Jörn Diedrichsen. "Restricted transfer of learning between unimanual and bimanual finger sequences." Journal of Neurophysiology 117, no. 3 (2017): 1043–51. http://dx.doi.org/10.1152/jn.00387.2016.
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When training bimanual skills, such as playing piano, people sometimes practice each hand separately and at a later stage combine the movements of the two hands. This poses the critical question of whether motor skills can be acquired by separately practicing each subcomponent or should be trained as a whole. In the present study, we addressed this question by training human subjects for 4 days in a unimanual or bimanual version of the discrete sequence production task. Both groups were then tested on trained and untrained sequences on both unimanual and bimanual versions of the task. Surprisingly, we found no evidence of transfer from trained unimanual to bimanual or from trained bimanual to unimanual sequences. In half the participants, we also investigated whether cuing the sequences on the left and right hand with unique letters would change transfer. With these cues, untrained sequences that shared some components with the trained sequences were performed more quickly than sequences that did not. However, the amount of this transfer was limited to ∼10% of the overall sequence-specific learning gains. These results suggest that unimanual and bimanual sequences are learned in separate representations. Making participants aware of the interrelationship between sequences can induce some transferrable component, although the main component of the skill remains unique to unimanual or bimanual execution. NEW & NOTEWORTHY Studies in reaching movement demonstrated that approximately half of motor learning can transfer across unimanual and bimanual contexts, suggesting that neural representations for unimanual and bimanual movements are fairly overlapping at the level of elementary movement. In this study, we show that little or no transfer occurred across unimanual and bimanual sequential finger movements. This result suggests that bimanual sequences are represented at a level of the motor hierarchy that integrates movements of both hands.
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Lin, Qiang, Hai Li, Yu-Rong Mao, et al. "The Difference of Neural Networks between Bimanual Antiphase and In-Phase Upper Limb Movements: A Preliminary Functional Magnetic Resonance Imaging Study." Behavioural Neurology 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/8041962.
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Most daily movements require some degree of collaboration between the upper limbs. The neural mechanisms are bimanual-condition specific and therefore should be different between different activities. In this study, we aimed to explore intraregional activation and interregional connectivity during bimanual movement by functional magnetic resonance imaging (fMRI). Ten right-handed, normal subjects were recruited. The neural correlates of unimanual (right side) and bimanual (in-phase and antiphase) upper limb movements were investigated. Connectivity analyses were carried out using the psychophysiological interaction (PPI) model. The cerebellum was strongly activated in both unimanual and bimanual movements, and the cingulate motor area (CMA) was the most activated brain area in antiphase bimanual movement. Moreover, compared with unimanual movement, CMA activation was also observed in antiphase bimanual movement, but not in in-phase bimanual movement. In addition, we carried out the PPI model to study the differences of effective connectivity and found that the cerebellum was more connected with the CMA during antiphase bimanual movement than in-phase bimanual movement. Our findings elucidate the differences of the cerebellar-cerebral functional connectivity between antiphase and in-phase bimanual movements, which could be used to facilitate the development of a neuroscience perspective on bimanual movement control in patients with motor impairments.
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Ridderikhoff, Arne, C. (Lieke) E. Peper, and Peter J. Beek. "Unraveling Interlimb Interactions Underlying Bimanual Coordination." Journal of Neurophysiology 94, no. 5 (2005): 3112–25. http://dx.doi.org/10.1152/jn.01077.2004.
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Three sources of interlimb interactions have been postulated to underlie the stability characteristics of bimanual coordination but have never been evaluated in conjunction: integrated timing of feedforward control signals, phase entrainment by contralateral afference, and timing corrections based on the perceived error of relative phase. In this study, the relative contributions of these interactions were discerned through systematic comparisons of five tasks involving rhythmic flexion–extension movements about the wrist, performed bimanually (in-phase and antiphase coordination) or unimanually with or without comparable passive movements of the contralateral hand. The main findings were the following. 1) Contralateral passive movements during unimanual active movements induced phase entrainment to interlimb phasing of either 0° (in-phase) or 180° (antiphase). 2) Entrainment strength increased with the passive movements' amplitude, but was similar for in-phase and antiphase movements. 3) Coordination of unimanual active movements with passive movements of the contralateral hand (kinesthetic tracking) was characterized by similar bilateral EMG activity as observed in active bimanual coordination. 4) During kinesthetic tracking the timing of the movements of the active hand was modulated by afference-based error corrections, which were more pronounced during in-phase coordination. 5) Indications of in-phase coordination being more stable than antiphase coordination were most prominent during active bimanual coordination and marginal during kinesthetic tracking. Together the results indicated that phase entrainment by contralateral afference contributed equally to the stability of in-phase and antiphase coordination, and that differential stability of these patterns depended predominantly on integrated timing of feedforward signals, with only a minor role for afference-based error corrections.
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Donchin, O., A. Gribova, O. Steinberg, A. R. Mitz, H. Bergman, and E. Vaadia. "Single-Unit Activity Related to Bimanual Arm Movements in the Primary and Supplementary Motor Cortices." Journal of Neurophysiology 88, no. 6 (2002): 3498–517. http://dx.doi.org/10.1152/jn.00335.2001.
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Single units were recorded from the primary motor (MI) and supplementary motor (SMA) areas of Rhesus monkeys performing one-arm (unimanual) and two-arm (bimanual) proximal reaching tasks. During execution of the bimanual movements, the task related activity of about one-half the neurons in each area (MI: 129/232, SMA: 107/206) differed from the activity during similar displacements of one arm while the other was stationary. The bulk of this “bimanual-related” activity could not be explained by any linear combination of activities during unimanual reaching or by differences in kinematics or recorded EMG activity. The bimanual-related activity was relatively insensitive to trial-to-trial variations in muscular activity or arm kinematics. For example, trials where bimanual arm movements differed the most from their unimanual controls did not correspond to the ones where the largest bimanual neural effects were observed. Cortical localization established by using a mixture of surface landmarks, electromyographic recordings, microstimulation, and sensory testing suggests that the recorded neurons were not limited to areas specifically involved with postural muscles. By rejecting this range of alternative explanations, we conclude that neural activity in MI as well as SMA can reflect specialized cortical processing associated with bimanual movements.
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Heitger, Marcus H., Marc J. M. Macé, Jan Jastorff, Stephan P. Swinnen, and Guy A. Orban. "Cortical regions involved in the observation of bimanual actions." Journal of Neurophysiology 108, no. 9 (2012): 2594–611. http://dx.doi.org/10.1152/jn.00408.2012.
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Although we are beginning to understand how observed actions performed by conspecifics with a single hand are processed and how bimanual actions are controlled by the motor system, we know very little about the processing of observed bimanual actions. We used fMRI to compare the observation of bimanual manipulative actions with their unimanual components, relative to visual control conditions equalized for visual motion. Bimanual action observation did not activate any region specialized for processing visual signals related to this more elaborated action. On the contrary, observation of bimanual and unimanual actions activated similar occipito-temporal, parietal and premotor networks. However, whole-brain as well as region of interest (ROI) analyses revealed that this network functions differently under bimanual and unimanual conditions. Indeed, in bimanual conditions, activity in the network was overall more bilateral, especially in parietal cortex. In addition, ROI analyses indicated bilateral parietal activation patterns across hand conditions distinctly different from those at other levels of the action-observation network. These activation patterns suggest that while occipito-temporal and premotor levels are involved with processing the kinematics of the observed actions, the parietal cortex is more involved in the processing of static, postural aspects of the observed action. This study adds bimanual cooperation to the growing list of distinctions between parietal and premotor cortex regarding factors affecting visual processing of observed actions.
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Poitras, Isabelle, Jade Clouâtre, Alexandre Campeau-Lecours, and Catherine Mercier. "Accelerometry-Based Metrics to Evaluate the Relative Use of the More Affected Arm during Daily Activities in Adults Living with Cerebral Palsy." Sensors 22, no. 3 (2022): 1022. http://dx.doi.org/10.3390/s22031022.
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Adults living with cerebral palsy (CP) report bimanual and unimanual difficulties that interfere with their participation in activities of daily living (ADL). There is a lack of quantitative methods to assess the impact of these motor dysfunctions on the relative use of each arm. The objective of this study was to evaluate the concurrent and discriminative validity of accelerometry-based metrics when used to assess bimanual and unimanual functions. Methods: A group of control subjects and hemiplegic adults living with CP performed six ADL tasks, during which they were wearing an Actigraph GT9X on each wrist and being filmed. Four bimanual and unimanual metrics were calculated from both accelerometry-based and video-based data; these metrics were then compared to one other with an intraclass correlation coefficient (ICC). Some of these metrics were previously validated in other clinical population, while others were novel. The discriminative validity was assessed through comparisons between groups and between tasks. Results: The concurrent validity was considered as good to excellent (ICC = 0.61–0.97) depending on the experience of the raters. The tasks made it possible to discriminate between groups. Conclusion: The proposed accelerometry-based metrics are a promising tool to evaluate bimanual and unimanual functions in adults living with CP.
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Öttl, Anton, Jonathan D. Kim, Dawn M. Behne, Pascal Gygax, Jukka Hyönä, and Ute Gabriel. "Exploring the comparative adequacy of a unimanual and a bimanual stimulus-response setup for use with three-alternative choice response time tasks." PLOS ONE 18, no. 3 (2023): e0281377. http://dx.doi.org/10.1371/journal.pone.0281377.
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Research often conceptualises complex social factors as being distinct binary categories (e.g., female vs male, feminine vs masculine). While this can be appropriate, the addition of an ‘overlapping’ category (e.g., non-binary, gender neutral) can contextualise the ‘binary’, both for participants (allowing more complex conceptualisations of the categories than the ‘either/or’ conceptualisation in binary tasks), and for the results (by providing a neutral baseline for comparison). However, it is not clear what the best response setup for such a task would be. In this study, we explore this topic through comparing a unimanual (N = 34) and a bimanual response setup (N = 32) for use with a three-alternative choice response time task. Crucially, one of the stimulus categories (‘mixed’) was composed of stimulus elements from the other two stimulus categories used in that task (Complex Task). A reference button task was included to isolate the motoric component of response registration (Simple Task). The results of the simple task indicated lower motoric costs for the unimanual compared to the bimanual setup. However, when statistically controlling for these motoric costs in the complex task, the bimanual setup had a lower error rate and faster response times than the unimanual setup. Further, in the complex task error rates and response times were higher for the mixed than the matched stimuli, indicating that responding to mixed stimuli is more challenging for encoding and/or decision making processes. This difference was more pronounced in the unimanual than the bimanual setup. Taken together these results indicate that the unimanual setup is more adequate for the reference button task, whereas the intricacy of overlapping categories in the complex task is better contained in the bimanual setup, i.e. when some response alternatives are allocated to one hand and other alternatives to the other hand.
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Azaad, Shaheed, and Simon M. Laham. "Sidestepping spatial confounds in object-based correspondence effects: The Bimanual Affordance Task (BMAT)." Quarterly Journal of Experimental Psychology 72, no. 11 (2019): 2605–13. http://dx.doi.org/10.1177/1747021819852216.
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Tucker and Ellis found that when participants made left/right button-presses to indicate whether objects were upright or inverted, responses were faster when the response hand aligned with the task-irrelevant handle orientation of the object. The effect of handle orientation on response times has been interpreted as evidence that individuals perceive grasp affordances when viewing briefly presented objects, which in turn activate grasp-related motor systems. Although the effect of handle alignment has since been replicated, there remains doubt regarding the extent to which the effect is indeed driven by affordance perception. Objects that feature in affordance-compatibility paradigms are asymmetrical and have laterally protruding handles (e.g., mugs) and thus confound spatial and affordance properties. Research has attempted to disentangle spatial compatibility and affordance effects with varying results. In this study, we present a novel paradigm with which to study affordance perception while sidestepping spatial confounds. We use the Bimanual Affordance Task (BMAT) to test whether object affordances in symmetrical objects facilitate response times. Participants ( N = 36) used one of three (left unimanual/right unimanual/bimanual) responses to indicate the colour of presented objects. Objects afforded either a unimanual (e.g., handbag) or a bimanual (e.g., laundry hamper) grasp. Responses were faster when the afforded grasp corresponded with the response type (unimanual vs. bimanual), suggesting that affordance effects exist independent of spatial compatibility.
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Patel, Shivangi shaileshkumar, and Jahanvi barot. "Effect of Unimanual Versus Bimanual Training on Impairment, Disability and Quality of Life Among Post Stroke Individuals: A Comparative Study." International Journal of Physiotherapy and Research 12, no. 5 (2024): 4777–83. http://dx.doi.org/10.16965/ijpr.2024.124.
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Background: Stroke is a significant global health issue caused by sudden interruptions in blood flow to the brain, leading to neurological dysfunction that can result in ischemic or hemorrhagic conditions. Effective rehabilitation approaches, such as unilateral and bilateral training, play a vital role in restoring upper limb function and overall recovery through targeted neural adaptations. Evaluation tools like the (SIS) provide critical insights into post-stroke recovery and improvements in quality of life, underscoring the need for comprehensive care and early intervention in managing this complex medical condition. Aim: To find out the effectiveness of unimanual and bimanual training on impairment, disability, and quality of life among post stroke individuals. Study design: comparative study Method: Firstly, ethical clearance was taken from the committee for comparative study. Samples were collected by lottery allotment sampling method. Thirty participants were selected based on inclusion and exclusion criteria. The details of the treatment were explained and written consent was taken from the participants. Experimental group treated with unimanual training and bimanual training for 5 days a week for 4 weeks. Outcome measure: Stroke impact scale Results: Data was analysed using SPSS Version29. According to statistical analysis, improvement seen in group B compared to group A. Conclusions: Bimanual training showed greater effective in impairment, disability and quality of life compared to unimanual training. KEYWORDS: Bimanual training, Unimanual training, stroke impact scale, quality of life, stroke.
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Panday, Virjanand, Wouter M. Bergmann Tiest, and Astrid M. L. Kappers. "Bimanual and unimanual length perception." Experimental Brain Research 232, no. 9 (2014): 2827–33. http://dx.doi.org/10.1007/s00221-014-3974-1.
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Chen, Jen-Tse, Yung-Yang Lin, Din-E. Shan, Zin-An Wu, Mark Hallett, and Kwong-Kum Liao. "Effect of Transcranial Magnetic Stimulation on Bimanual Movements." Journal of Neurophysiology 93, no. 1 (2005): 53–63. http://dx.doi.org/10.1152/jn.01063.2003.
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Transcranial magnetic stimulation (TMS) of the motor cortex can interrupt voluntary contralateral rhythmic limb movements. Using the method of “resetting index” (RI), our study investigated the TMS effect on different types of bimanual movements. Six normal subjects participated. For unimanual movement, each subject tapped either the right or left index finger at a comfortable rate. For bimanual movement, index fingers of both hands tapped in the same (in-phase) direction or in the opposite (antiphase) direction. TMS was applied to each hemisphere separately at various intensities from 0.5 to 1.5 times motor threshold (MT). TMS interruption of rhythm was quantified by RI. For the unimanual movements, TMS disrupted both contralateral and ipsilateral rhythmic hand movements, although the effect was much less in the ipsilateral hand. For the bimanual in-phase task, TMS could simultaneously reset the rhythmic movements of both hands, but the effect on the contralateral hand was less and the effect on the ipsilateral hand was more compared with the unimanual tasks. Similar effects were seen from right and left hemisphere stimulation. TMS had little effect on the bimanual antiphase task. The equal effect of right and left hemisphere stimulation indicates that neither motor cortex is dominant for simple bimanual in-phase movement. The smaller influence of contralateral stimulation and the greater effect of ipsilateral stimulation during bimanual in-phase movement compared with unimanual movement suggest hemispheric coupling. The antiphase movements were resistant to TMS disruption, and this suggests that control of rhythm differs in the 2 tasks. TMS produced a transient asynchrony of movements on the 2 sides, indicating that both motor cortices might be downstream of the clocking command or that the clocking is a consequence of the 2 hemispheres communicating equally with each other.
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Ko, Do-Kyung, and Nyeonju Kang. "Aging Impairs Unimanual and Bimanual Hand-Grip Force Control Capabilities." Applied Sciences 14, no. 11 (2024): 4408. http://dx.doi.org/10.3390/app14114408.
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This study examined age-related changes in unimanual and bimanual hand-grip force control capabilities by focusing on absolute and relative outcome measures. Thirty-two older adults and thirty-two younger adults performed isometric hand-grip force control tasks across three hand conditions (unimanual dominant, unimanual non-dominant, and bimanual) and two submaximal targeted levels (10% and 40% of maximal voluntary contraction). Force control performances were evaluated by calculating absolute and relative variables on force accuracy and variability. Furthermore, to determine which force control variables and experimental conditions effectively indicate age-related sensorimotor control deficits, we conducted receiver operating characteristic curve analyses. Older adults demonstrated impaired force control capabilities at 10% of maximal voluntary contraction collapse across the three hand conditions compared with younger adults, and these deficits were identified by both relative force accuracy and relative force variability. Moreover, relative force accuracy showed a good diagnostic quality at 10% of maximal voluntary contraction. These findings suggested that aging may induce unimanual and bimanual hand-grip force control deficits at a lower targeted level, and these motor impairments were sensitively estimated by quantifying relative force control outcome measures that may reflect age-related muscle weakness as compared with absolute measurements.
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Lee-Miller, Trevor, Marco Santello, and Andrew M. Gordon. "Hand forces and placement are modulated and covary during anticipatory control of bimanual manipulation." Journal of Neurophysiology 121, no. 6 (2019): 2276–90. http://dx.doi.org/10.1152/jn.00760.2018.
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Dexterous object manipulation relies on the feedforward and feedback control of kinetics (forces) and kinematics (hand shaping and digit placement). Lifting objects with an uneven mass distribution involves the generation of compensatory moments at object lift-off to counter object torques. This is accomplished through the modulation and covariation of digit forces and placement, which has been shown to be a general feature of unimanual manipulation. These feedforward anticipatory processes occur before performance-specific feedback. Whether this adaptation is a feature unique to unimanual dexterous manipulation or general across unimanual and bimanual manipulation is not known. We investigated the generation of compensatory moments through hand placement and force modulation during bimanual manipulation of an object with variable center of mass. Participants were instructed to prevent object roll during the lift. Similar to unimanual grasping, we found modulation and covariation of hand forces and placement for successful performance. Thus this motor adaptation of the anticipatory control of compensatory moment is a general feature across unimanual and bimanual effectors. Our results highlight the involvement of high-level representation of manipulation goals and underscore a sensorimotor circuitry for anticipatory control through a continuum of force and placement modulation of object manipulation across a range of effectors. NEW & NOTEWORTHY This is the first study, to our knowledge, to show that successful bimanual manipulation of objects with asymmetrical centers of mass is performed through the modulation and covariation of hand forces and placements to generate compensatory moments. Digit force-to-placement modulation is thus a general phenomenon across multiple effectors, such as the fingers of one hand, and both hands. This adds to our understanding of integrating low-level internal representations of object properties into high-level task representations.
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Laha, Bireswar, Jeremy N. Bailenson, Andrea Stevenson Won, and Jakki O. Bailey. "Evaluating Control Schemes for the Third Arm of an Avatar." Presence: Teleoperators and Virtual Environments 25, no. 2 (2016): 129–47. http://dx.doi.org/10.1162/pres_a_00251.
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Recent research on immersive virtual environments has shown that users can not only inhabit and identify with novel avatars with novel body extensions, but also learn to control novel appendages in ways beneficial to the task at hand. But how different control schemas might affect task performance and body ownership with novel avatar appendages has yet to be explored. In this article, we discuss the design of control schemas based on the theory and practice of 3D interactions applied to novel avatar bodies. Using a within-subjects design, we compare the effects of controlling a third arm with three different control schemas (bimanual, unimanual, and head-control) on task performance, simulator sickness, presence, and user preference. Both the unimanual and the head-control were significantly faster, elicited significantly higher body ownership, and were preferred over the bimanual control schema. Participants felt that the bimanual control was significantly more difficult than the unimanual control, and elicited less appendage agency than the head-control. There were no differences in reported simulator sickness. We discuss the implications of these results for interface design.
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Razali, Haziq, and Yiannis Demiris. "Forecasting Bimanual Object Manipulation Sequences from Unimanual Observations." Proceedings of the AAAI Conference on Artificial Intelligence 38, no. 5 (2024): 4659–66. http://dx.doi.org/10.1609/aaai.v38i5.28266.
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Learning to forecast bimanual object manipulation sequences from unimanual observations has broad applications in assistive robots and augmented reality. This challenging task requires us to first infer motion from the missing arm and the object it would have been manipulating were the person bimanual, then forecast the human and object motion while maintaining hand-object contact during manipulation. Previous attempts model the hand-object interactions only implicitly, and thus tend to produce unrealistic motion where the objects float in air. We address this with a novel neural network that (i) identifies and forecasts the pose for only the objects undergoing motion through an object motion module and (ii) refines human pose predictions by encouraging hand-object contact during manipulation through an ensemble of human pose predictors. The components are also designed to be generic enough for use in both unimanual and bimanual contexts. Our approach outperforms the state-of-the-art pose forecasting methods on bimanual manipulation datasets.
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Hinder, Mark R., Timothy J. Carroll, and Jeffery J. Summers. "Transfer of ballistic motor skill between bilateral and unilateral contexts in young and older adults: neural adaptations and behavioral implications." Journal of Neurophysiology 109, no. 12 (2013): 2963–71. http://dx.doi.org/10.1152/jn.00535.2012.
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Bilateral movement rehabilitation is gaining popularity as an approach to improve the recovery not only of bimanual function but also of unilateral motor tasks. While the neural mechanisms mediating the transfer of bilateral training gains into unimanual contexts are not fully understood, converging evidence from behavioral, neurophysiological, and imaging studies suggests that bimanual movements are not simply the superposition of unimanual tasks undertaken with both (upper) limbs. Here we investigated the neural responses in both hemispheres to bilateral ballistic motor training and the extent to which performance improvements transferred to a unimanual task. Since aging influences interhemispheric interactions during movement production, both young ( n = 9; mean age 19.4 yr; 6 women, 3 men) and older ( n = 9; 66.3 yr; 7 women, 2 men) adults practiced a bilateral motor task requiring simultaneous “fast-as-possible” abductions of their left and right index fingers. Changes in bilateral and unilateral performance, and in corticospinal excitability and intracortical inhibition, were assessed. Strong transfer was observed between bimanual and unimanual contexts for both age groups. However, in contrast to previous reports of substantial bilateral cortical adaptations following unilateral training, increases in corticospinal excitability following bilateral training were not statistically reliable, and a release of intracortical inhibition was only observed for older adults. The results indicate that the neural mechanisms of motor learning for bilateral ballistic tasks differ from those that underlie unimanual ballistic performance improvement but that aging results in a greater overlap of the neural mechanisms mediating bilateral and unilateral ballistic motor performance.
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Dounskaia, Natalia, Keith G. Nogueira, Stephan P. Swinnen, and Elizabeth Drummond. "Limitations on Coupling of Bimanual Movements Caused by Arm Dominance: When the Muscle Homology Principle Fails." Journal of Neurophysiology 103, no. 4 (2010): 2027–38. http://dx.doi.org/10.1152/jn.00778.2009.
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Studies of bimanual movements typically report interference between motions of the two arms and preference to perform mirror-symmetrical patterns. However, recent studies have demonstrated that the two arms differ in the ability to control interaction torque (INT). This predicts limitations in the capability to perform mirror-symmetrical movements. Here, two experiments were performed to test this prediction. The first experiment included bimanual symmetrical and asymmetrical circle drawing at two frequency levels. Unimanual circle drawing was also recorded. The increases in cycling frequency caused differences between the two arms in movement trajectories in both bimanual modes, although the differences were more pronounced in the asymmetrical compared with the symmetrical mode. Based on torque analysis, the differences were attributed to the nondominant arm's decreased capability to control INT. The intraarm differences during the symmetrical pattern of bimanual movements were similar (although more pronounced) to those during unimanual movements. This finding was verified in the second experiment for symmetrical bimanual oval drawing. Four oval orientations were used to provide variations in INT. Similar to the first experiment, increases in cycling frequency caused spontaneous deviations from perfect bimanual symmetry associated with inefficient INT control in the nondominant arm. This finding supports the limitations in performing mirror-symmetrical bimanual movements due to differences in joint control between the arms. Based on our results and previous research, we argue that bimanual interference occurs during specification of characteristics of required motion, whereas lower-level generation of muscle forces is independent between the arms. A hierarchical model of bimanual control is proposed.
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Plantin, Jeanette, Marion Verneau, Alison K. Godbolt, et al. "Recovery and Prediction of Bimanual Hand Use After Stroke." Neurology 97, no. 7 (2021): e706-e719. http://dx.doi.org/10.1212/wnl.0000000000012366.
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ObjectiveTo determine similarities and differences in key predictors of recovery of bimanual hand use and unimanual motor impairment after stroke.MethodIn this prospective longitudinal study, 89 patients with first-ever stroke with arm paresis were assessed at 3 weeks and 3 and 6 months after stroke onset. Bimanual activity performance was assessed with the Adult Assisting Hand Assessment Stroke (Ad-AHA), and unimanual motor impairment was assessed with the Fugl-Meyer Assessment (FMA). Candidate predictors included shoulder abduction and finger extension measured by the corresponding FMA items (FMA-SAFE; range 0–4) and sensory and cognitive impairment. MRI was used to measure weighted corticospinal tract lesion load (wCST-LL) and resting-state interhemispheric functional connectivity (FC).ResultsInitial Ad-AHA performance was poor but improved over time in all (mild-severe) impairment subgroups. Ad-AHA correlated with FMA at each time point (r > 0.88, p < 0.001), and recovery trajectories were similar. In patients with moderate to severe initial FMA, FMA-SAFE score was the strongest predictor of Ad-AHA outcome (R2 = 0.81) and degree of recovery (R2 = 0.64). Two-point discrimination explained additional variance in Ad-AHA outcome (R2 = 0.05). Repeated analyses without FMA-SAFE score identified wCST-LL and cognitive impairment as additional predictors. A wCST-LL >5.5 cm3 strongly predicted low to minimal FMA/Ad-AHA recovery (≤10 and 20 points respectively, specificity = 0.91). FC explained some additional variance to FMA-SAFE score only in unimanual recovery.ConclusionAlthough recovery of bimanual activity depends on the extent of corticospinal tract injury and initial sensory and cognitive impairments, FMA-SAFE score captures most of the variance explained by these mechanisms. FMA-SAFE score, a straightforward clinical measure, strongly predicts bimanual recovery.ClinicalTrials.gov IdentifierNCT02878304.Classification of EvidenceThis study provides Class I evidence that the FMA-SAFE score predicts bimanual recovery after stroke.
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Wang, Chaoyi, and Charles H. Shea. "Bimanual control strategies." Quarterly Journal of Experimental Psychology 72, no. 4 (2018): 966–78. http://dx.doi.org/10.1177/1747021818781772.
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Two tasks (A and B) were designed which required participants to sequentially move through four target positions in a Lissajous display. Task A was designed so that participants could complete the task using either unimanual or bimanual control strategies. Task B was designed so that participants could complete the task using relatively simple or more complex bimanual control strategies. The purpose of this study was to determine which control strategy the participant utilises to complete the two tasks when Lissajous displays are provided and to determine the degree to which the size of the targets influences the control strategy chosen under these conditions. The movement amplitude between two adjacent targets and the target size resulted in an Index of Difficulty (ID) of 2 and 4 for each task. For both tasks, participants practised 15 trials (30 s per trial) for each ID and then was administered a test trial. The results for both Tasks A and B indicated that the ID2 condition resulted in a circular path, whereas the ID4 condition resulted in a straight-line path on the Lissajous plot. This suggests that at the low ID condition participants produced a continuous 1:1 with 90° phase offset bimanual coordination pattern. At the high ID condition, the participants consistently chose to switch to a more stable unimanual left and right movements in Task A and to transition between in-phase and anti-phase bimanual coordination patterns in Task B. In addition, both limbs’ movements were more harmonic in the low ID condition than in the high ID condition.
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Pollok, Bettina, Markus Butz, Joachim Gross, and Alfons Schnitzler. "Intercerebellar Coupling Contributes to Bimanual Coordination." Journal of Cognitive Neuroscience 19, no. 4 (2007): 704–19. http://dx.doi.org/10.1162/jocn.2007.19.4.704.
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Compared to unimanual task execution, simultaneous bimanual tapping tasks are associated with a significantly reduced intertap variability. It has been suggested that this bimanual advantage is based on the integration of timing signals which otherwise control each hand independently. Although its functional and anatomic foundations are poorly understood, functional coupling between cerebellar hemispheres might be behind this process. Because the execution of fast alternating fingertaps increases intertap variability, it is hypothesized that intercerebellar coupling is reduced in such tasks. To shed light on the functional significance of intercerebellar coupling, 14 right-handed subjects performed unimanual right, bimanual simultaneous, and bimanual alternating synchronization tasks with respect to a regular auditory pacing signal. In all conditions, within-hand intertap interval was 500 msec. Continuous neuromagnetic activity, using a 122-channel wholehead neuromagnetometer and surface electromyograms of the first dorsal interosseus muscle of both hands, were recorded. For data analysis, we used the analysis tool Dynamic Imaging of Coherent Sources, which provides a tomographic map of cerebromuscular and cerebrocerebral coherence. Analysis revealed a bilateral cerebello-thalamo-cortical network oscillating at alpha (8–12 Hz) and beta (13–24 Hz) frequencies associated with bimanual synchronization. In line with our hypothesis, coupling between cerebellar hemispheres was restricted to simultaneous task execution. This result implies that intercerebellar coupling is key for the execution of simultaneous bimanual movements. Although the criticality of a specific magneto-encephalography pattern for behavioral changes should be interpreted with caution, data suggest that intercerebellar coupling possibly represents the functional foundation of the bimanual advantage.
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Blinch, Jarrod, Brendan D. Cameron, Erin K. Cressman, Ian M. Franks, Mark G. Carpenter, and Romeo Chua. "Comparing movement preparation of unimanual, bimanual symmetric, and bimanual asymmetric movements." Experimental Brain Research 232, no. 3 (2014): 947–55. http://dx.doi.org/10.1007/s00221-013-3807-7.
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Goerres, Gerhard W., Michael Samuel, I. Harri Jenkins, and David J. Brooks. "Cerebral control of unimanual and bimanual movements." NeuroReport 9, no. 16 (1998): 3631–38. http://dx.doi.org/10.1097/00001756-199811160-00014.
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Stinear, Cathy M., Melanie K. Fleming, and Winston D. Byblow. "Lateralization of unimanual and bimanual motor imagery." Brain Research 1095, no. 1 (2006): 139–47. http://dx.doi.org/10.1016/j.brainres.2006.04.008.
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Robert, Maxime T., Jennifer Gutterman, Claudio L. Ferre, et al. "Corpus Callosum Integrity Relates to Improvement of Upper-Extremity Function Following Intensive Rehabilitation in Children With Unilateral Spastic Cerebral Palsy." Neurorehabilitation and Neural Repair 35, no. 6 (2021): 534–44. http://dx.doi.org/10.1177/15459683211011220.
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Background The corpus callosum (CC) plays an important role in upper extremity (UE) function. The impact on UE function in children with unilateral spastic cerebral palsy (USCP) and improvements following intensive interventions remain unknown. Objectives To examine the (1) relationship between UE function and CC integrity and (2) relationship between CC integrity and changes in UE function following intensive interventions. Methods We retrospectively analyzed clinical and neuroimaging data from a sample of convenience of 44 participants (age 9.40 ± 3.10 years) from 2 larger trials. Participants received 90 hours of Hand-Arm Bimanual Intensive Therapy (HABIT) or Constraint-Induced Movement Therapy (CIMT). Unimanual dexterity (Jebsen-Taylor Test of Hand Function [JTTHF]) and bimanual performance (Assisting Hand Assessment [AHA]) were assessed preintervention and postintervention. CC tractography was reconstructed with diffusion tensor imaging (DTI) and segmented into 3 regions (genu, midbody, splenium). Pearson correlations and regression were used to assess the relationship between outcomes and DTI parameters (ie, fractional anisotropy [FA], number of streamlines, and mean, radial, and axial diffusivity). Results Both groups improved in bimanual performance ( P < .01). The CIMT group improved in unimanual dexterity ( P < .01). Baseline unimanual dexterity and bimanual performance correlated with FA and number of streamlines for most CC regions ( P < .05). Following CIMT, pre-post changes in JTTHF were negatively correlated with axial and radial diffusivity of the CC, and AHA with splenium and number of streamlines for the CC, midbody, and splenium (all P < .05). Following HABIT, midbody FA was positively correlated with pre-post AHA changes ( r = 0.417; P = .042). Conclusions CC integrity is important for UE function in children with USCP.
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Fujii, Shinya, Kazutoshi Kudo, Tatsuyuki Ohtsuki, and Shingo Oda. "Intrinsic Constraint of Asymmetry Acting as a Control Parameter on Rapid, Rhythmic Bimanual Coordination: A Study of Professional Drummers and Nondrummers." Journal of Neurophysiology 104, no. 4 (2010): 2178–86. http://dx.doi.org/10.1152/jn.00882.2009.
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Expert musicians show experience-dependent reduced asymmetry in the structure of motor-related brain areas and in the maximum tapping frequency between the hands. Therefore we hypothesized that a reduced hand-skill asymmetry is strongly related to rapid and rhythmical bimanual coordination and developed a dynamical model including a symmetry-breaking parameter Δω, for human bimanual coordination. We conducted unimanual and bimanual drumming experiments to test the following model predictions. 1) The asymmetry in the maximum tapping frequency is more pronounced in nondrummers than that in drummers. If so, 2) a larger number of phase wanderings (i.e., succession of taps by the same hand), 3) larger SD of the relative phase between the hands ( SD ϕ), and 4) larger deviation of mean relative phase (mean ϕ) from 180° would be observed in nondrummers than that in professional drummers during antiphase bimanual drumming at the maximum speed. In a unimanual tapping task, the asymmetry in maximum tapping frequency of nondrummers was more pronounced than that of professional drummers. In a bimanual coordination task, phase wanderings were observed only in nondrummers and SD ϕ of the nondrummers is significantly larger than that of professional drummers. On the other hand, there was no significant difference between the mean ϕ of the two groups. All these observations were successfully reproduced by changing Δω, which corresponded to the asymmetry in the maximum tapping frequency. These results support the hypothesis indicating that the prominent bimanual coordination pattern emerges spontaneously after a nonspecific change in Δω or symmetry restoration of the nonlinear dynamical systems.
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Rahman, S. M. Mizanoor, and Ryojun Ikeura. "Weight-perception-based fixed and variable admittance control algorithms for unimanual and bimanual lifting of objects with a power assist robotic system." International Journal of Advanced Robotic Systems 15, no. 4 (2018): 172988141667813. http://dx.doi.org/10.1177/1729881416678131.
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Weight-perception-based fixed admittance control algorithm and variable admittance control algorithm are proposed for unimanual and bimanual lifting of objects with a power assist robotic system. To include weight perception in controls, the mass parameter for the inertial force is hypothesized as different from that for the gravitational force in the dynamics model for lifting objects with the system. For the bimanual lift, two alternative approaches of force sensor arrangements are considered: a common force sensor and two separate force sensors between object and human hands. Computational models for power assistance, excess in load forces, and manipulation efficiency and precision are derived. The fixed admittance control algorithm is evaluated in a 1-degree-of-freedom power assist robotic system. Results show that inclusion of weight perception in controls produce satisfactory performance in terms of power assistance, system kinematics and kinetics, human–robot interactions, and manipulation efficiency and precision. The fixed admittance control algorithm is then augmented to variable admittance control algorithm as a tool of active compliance to vary the admittance with inertia instead of with gravity. The evaluation shows further improvement in the performance for the variable admittance control algorithm. The evaluation also shows that bimanual lifts outperform unimanual lifts and bimanual lifts with separate force sensors outperform bimanual lifts with a common force sensor. Then, the results are proposed to develop power assist robotic systems for handling heavy objects in industries.
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Srinivasan, Sudha, Patrick Kumavor, and Kristin Morgan. "A Training Program Using Modified Joystick-Operated Ride-on Toys to Complement Conventional Upper Extremity Rehabilitation in Children with Cerebral Palsy: Results from a Pilot Study." Bioengineering 11, no. 4 (2024): 304. http://dx.doi.org/10.3390/bioengineering11040304.
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The pilot study assessed the utility of a training program using modified, commercially available dual-joystick-operated ride-on toys to promote unimanual and bimanual upper extremity (UE) function in children with cerebral palsy (CP). The ride-on-toy training was integrated within a 3-week, intensive, task-oriented training camp for children with CP. Eleven children with hemiplegia between 4 and 10 years received the ride-on-toy training program 20–30 min/day, 5 days/week for 3 weeks. Unimanual motor function was assessed using the Quality of Upper Extremity Skills Test (QUEST) before and after the camp. During ride-on-toy training sessions, children wore activity monitors on both wrists to assess the duration and intensity of bimanual UE activity. Video data from early and late sessions were coded for bimanual UE use, independent navigation, and movement bouts. Children improved their total and subscale QUEST scores from pretest to post-test while increasing moderate activity in their affected UE from early to late sessions, demonstrating more equal use of both UEs across sessions. There were no significant changes in the rates of movement bouts from early to late sessions. We can conclude that joystick-operated ride-on toys function as child-friendly, intrinsically rewarding tools that can complement conventional therapy and promote bimanual motor functions in children with CP.
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Proctor, Robert W., and Yang Seok Cho. "Effects of Response Eccentricity and Relative Position on Orthogonal Stimulus—Response Compatibility with Joystick and Keypress Responses." Quarterly Journal of Experimental Psychology Section A 56, no. 2 (2003): 309–27. http://dx.doi.org/10.1080/02724980244000350.
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When unimanual left—right movement responses are made to up—down stimuli, performance is better with the up—right/down—left mapping when responding in the right hemispace and with the up—left/down—right mapping when responding in the left hemispace. We evaluated whether this response eccentricity effect is explained best in terms of rotational properties of the hand (the end-state comfort hypothesis) or asymmetric coding of the stimulus and response alternatives (the salient features coding hypothesis). Experiment 1 showed that bimanual keypresses yield a response eccentricity effect similar to that obtained with unimanual movement responses. In Experiment 2, an inactive response apparatus was placed to the left or right of the active response apparatus to provide a referent. For half of the participants, the active and inactive apparatuses were joysticks, and for half they were response boxes with keys. For both response types, an up—right/down—left advantage was evident when the relative position of the active response apparatus was right but not when it was left. That bimanual keypresses yield similar eccentricity and relative location effects to those for unimanual movements is predicted by the salient features coding perspective but not by the end-state comfort hypothesis.
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Masumoto, Junya, and Nobuyuki Inui. "Motor control hierarchy in joint action that involves bimanual force production." Journal of Neurophysiology 113, no. 10 (2015): 3736–43. http://dx.doi.org/10.1152/jn.00313.2015.
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The concept of hierarchical motor control has been viewed as a means of progressively decreasing the number of variables manipulated by each higher control level. We tested the hypothesis that turning an individual bimanual force-production task into a joint (two-participant) force-production task would lead to positive correlation between forces produced by the two hands of the individual participant (symmetric strategy) to enable negative correlation between forces produced by two participants (complementary strategy). The present study consisted of individual and joint tasks that involved both unimanual and bimanual conditions. In the joint task, 10 pairs of participants produced periodic isometric forces, such that the sum of forces that they produced matched a target force cycling between 5% and 10% of maximum voluntary contraction at 1 Hz. In the individual task, individuals attempted to match the same target force. In the joint bimanual condition, the two hands of each participant adopted a symmetric strategy of force, whereas the two participants adopted a complementary strategy of force, highlighting that the bimanual action behaved as a low level of a hierarchy, whereas the joint action behaved as an upper level. The complementary force production was greater interpersonally than intrapersonally. However, whereas the coherence was highest at 1 Hz in all conditions, the frequency synchrony was stronger intrapersonally than interpersonally. Moreover, whereas the bimanual action exhibited a smaller error and variability of force than the unimanual action, the joint action exhibited a less-variable interval and force than the individual action.
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Koeneke, Susan, Kai Lutz, Torsten Wüstenberg, and Lutz Jäncke. "Bimanual versus unimanual coordination: what makes the difference?" NeuroImage 22, no. 3 (2004): 1336–50. http://dx.doi.org/10.1016/j.neuroimage.2004.03.012.
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Serrien, Deborah J. "Coordination constraints during bimanual versus unimanual performance conditions." Neuropsychologia 46, no. 2 (2008): 419–25. http://dx.doi.org/10.1016/j.neuropsychologia.2007.08.011.
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Barral, Jerome, Bettina Debu, and Christina Rival. "Developmental Changes in Unimanual and Bimanual Aiming Movements." Developmental Neuropsychology 29, no. 3 (2006): 415–29. http://dx.doi.org/10.1207/s15326942dn2903_2.
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P., Verbessem, B. Op't Eijnde, Swinnen S., Vangheluwe S., Hespel P., and Dom R. "Unimanual and bimanual voluntary movement in Huntington's disease." Experimental Brain Research 147, no. 4 (2002): 529–37. http://dx.doi.org/10.1007/s00221-002-1270-y.
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Mason, Andrea H. "Performance of Unimanual and Bimanual Multiphased Prehensile Movements." Journal of Motor Behavior 39, no. 4 (2007): 291–305. http://dx.doi.org/10.3200/jmbr.39.4.291-305.
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Hoffmann, Errol R., Alan H. S. Chan, and Steve N. H. Tsang. "Bimanual and Unimanual Convergent Goal-Directed Movement Times." Journal of Motor Behavior 47, no. 3 (2014): 232–45. http://dx.doi.org/10.1080/00222895.2014.974494.
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Squeri, Valentina, Alessandra Sciutti, Monica Gori, Lorenzo Masia, Giulio Sandini, and Juergen Konczak. "Two hands, one perception: how bimanual haptic information is combined by the brain." Journal of Neurophysiology 107, no. 2 (2012): 544–50. http://dx.doi.org/10.1152/jn.00756.2010.
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Humans routinely use both of their hands to gather information about shape and texture of objects. Yet, the mechanisms of how the brain combines haptic information from the two hands to achieve a unified percept are unclear. This study systematically measured the haptic precision of humans exploring a virtual curved object contour with one or both hands to understand if the brain integrates haptic information from the two hemispheres. Bayesian perception theory predicts that redundant information from both hands should improve haptic estimates. Thus exploring an object with two hands should yield haptic precision that is superior to unimanual exploration. A bimanual robotic manipulandum passively moved the hands of 20 blindfolded, right-handed adult participants along virtual curved contours. Subjects indicated which contour was more “curved” (forced choice) between two stimuli of different curvature. Contours were explored uni- or bimanually at two orientations (toward or away from the body midline). Respective psychophysical discrimination thresholds were computed. First, subjects showed a tendency for one hand to be more sensitive than the other with most of the subjects exhibiting a left-hand bias. Second, bimanual thresholds were mostly within the range of the corresponding unimanual thresholds and were not predicted by a maximum-likelihood estimation (MLE) model. Third, bimanual curvature perception tended to be biased toward the motorically dominant hand, not toward the haptically more sensitive left hand. Two-handed exploration did not necessarily improve haptic sensitivity. We found no evidence that haptic information from both hands is integrated using a MLE mechanism. Rather, results are indicative of a process of “sensory selection”, where information from the dominant right hand is used, although the left, nondominant hand may yield more precise haptic estimates.
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Nakajima, Toshi, Haruka Arisawa, Ryosuke Hosaka та Hajime Mushiake. "Intended arm use influences interhemispheric correlation of β-oscillations in primate medial motor areas". Journal of Neurophysiology 118, № 5 (2017): 2865–83. http://dx.doi.org/10.1152/jn.00379.2016.
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To investigate the role of interhemispheric β-synchronization in the selection of motor effectors, we trained two monkeys to memorize and perform multiple two-movement sequences that included unimanual repetition and bimanual switching. We recorded local field potentials simultaneously in the bilateral supplementary motor area (SMA) and pre-SMA to examine how the β-power in both hemispheres and the interhemispheric relationship of β-oscillations depend on the prepared sequence of arm use. We found a significant ipsilateral enhancement of β-power for bimanual switching trials in the left hemisphere and an enhancement of β-power in the right SMA while preparing for unimanual repetition. Furthermore, interhemispheric synchrony in the SMA was significantly more enhanced while preparing unimanual repetition than while preparing bimanual switching. This enhancement of synchrony was detected in terms of β-phase but not in terms of modulation of β-power. Furthermore, the assessment of the interhemispheric phase difference revealed that the β-oscillation in the hemisphere contralateral to the instructed arm use significantly advanced its phase relative to that in the ipsilateral hemisphere. There was no arm use-dependent shift in phase difference in the pairwise recordings within each hemisphere. Both neurons with and without arm use-selective activity were phase-locked to the β-oscillation. These results imply that the degree of interhemispheric phase synchronization as well as phase differences and oscillatory power in the β-band may contribute to the selection of arm use depending on the behavioral conditions of sequential arm use. NEW & NOTEWORTHY We addressed interhemispheric relationships of β-oscillations during bimanual coordination. While monkeys prepared to initiate movement of the instructed arm, β-oscillations in the contralateral hemisphere showed a phase advance relative to the other hemisphere. Furthermore, the sequence of arm use influenced β-power and the degree of interhemispheric phase synchronization. Thus the dynamics of interhemispheric phases and power in β-oscillations may contribute to the specification of motor effectors in a given behavioral context.
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Chen, Siyun, Mengchai Mao, Guangyue Zhu, et al. "Cortical activity in patients with high-functioning ischemic stroke during the Purdue Pegboard Test: insights into bimanual coordinated fine motor skills with functional near-infrared spectroscopy." Neural Regeneration Research 19, no. 5 (2023): 1098–104. http://dx.doi.org/10.4103/1673-5374.385312.
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Abstract JOURNAL/nrgr/04.03/01300535-202405000-00040/inline-graphic1/v/2023-09-28T063346Z/r/image-tiff After stroke, even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity, leading to reduced functional independence. Bilateral arm training has been proposed as a promising intervention to address these deficits. However, the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear, limiting the development of more targeted interventions. To address this gap, our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination. Twenty-four high-functioning patients with ischemic stroke (7 women, 17 men; mean age 64.75 ± 10.84 years) participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test, which measures unimanual and bimanual finger and hand dexterity. We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks, with bimanual tasks inducing higher cortical activation than the assembly subtask. Importantly, patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks. Notably, the observed neural response patterns varied depending on the specific subtask. In the unaffected hand task, the differences were primarily observed in the ipsilesional hemisphere. In contrast, the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task, respectively. While significant correlations were found between cortical activation and unimanual tasks, no significant correlations were observed with bimanual tasks. This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke, highlighting task-dependent neural responses. The findings also suggest that patients who exhibit better bimanual performance demonstrate more efficient cortical activation. Therefore, incorporating bilateral arm training in post-stroke rehabilitation is important for better outcomes. The combination of functional near-infrared spectroscopy with functional motor paradigms is valuable for assessing skills and developing targeted interventions in stroke rehabilitation.
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Mooshagian, Eric, Cunguo Wang, Afreen Ferdoash, and Lawrence H. Snyder. "Movement order and saccade direction affect a common measure of eye-hand coordination in bimanual reaching." Journal of Neurophysiology 112, no. 3 (2014): 730–39. http://dx.doi.org/10.1152/jn.00234.2014.
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Studies of visually guided unimanual reaching have established that a saccade usually precedes each reach and that the reaction times (RTs) for the saccade and reach are highly correlated. The correlation of eye and hand RT is commonly taken as a measure of eye-hand coordination and is thought to assist visuospatial guidance of the hand. We asked what happens during a bimanual reach task. As with a unimanual reach, a saccade was executed first. Although latencies were fastest on unimanual trials, eye and hand RT correlation was identical whether just one or both hands reached to a single target. The average correlation was significantly reduced, however, when each hand reached simultaneously to a different target. We considered three factors that might explain the drop. We found that correlation strength depended on which hand reached first and on which hand reached to the same target as the saccade. Surprisingly, these two factors were largely independent, and the identity of the hand, left or right, had little effect. Eye-hand correlation was similar to that seen with unimanual reaching only when the hand that moved to the same target as the saccade was also the first hand to move. Thus both timing as well as spatial pattern are important in determining eye-hand coordination.
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Rolán, Katia, Iván Sánchez-Borges, Boris Kogan, et al. "The embodied typist: Bimanual actions are modulated by words’ implied motility and number of evoked limbs." PLOS ONE 18, no. 8 (2023): e0289926. http://dx.doi.org/10.1371/journal.pone.0289926.
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The planning and execution of manual actions can be influenced by concomitant processing of manual action verbs. However, this phenomenon manifests in varied ways throughout the literature, ranging from facilitation to interference effects. Suggestively, stimuli across studies vary randomly in two potentially relevant variables: verb motility and effector quantity (i.e., the amount of movement and the number of hands implied by the word, respectively). Here we examine the role of these factors during keyboard typing, a strategic bimanual task validated in previous works. Forty-one participants read and typed high and low motility items from four categories: bimanual, unimanual, and non-manual action verbs, as well as minimally motoric verbs. Motor planning and execution were captured by first-letter lag (the lapse between word presentation and first keystroke) and whole-word lag (the lapse between the first and last keystroke). We found that verb motility modulated action planning and execution, both stages being delayed by high (relative to low) motility verbs. Effector quantity also influenced both stages, which were facilitated by bimanual verbs relative to unimanual verbs and non-manual verbs (this effect being confined to high motility items during action execution). Accordingly, motor-language coupling effects seem sensitive to words’ implied motility and number of evoked limbs. These findings refine our understanding of how semantics influences bodily movement.
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Studenka, Breanna E., Daisha L. Cummins, and Megan A. Pope. "The role of multiple internal timekeepers and sources of feedback on interval timing." Quarterly Journal of Experimental Psychology 71, no. 9 (2018): 1960–67. http://dx.doi.org/10.1080/17470218.2017.1373835.
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The aim of this experiment was to document the role of multiple internal clock mechanisms and external sources of temporal feedback on reducing timing variability when two fingers tap instead of one (a phenomenon known as the bimanual advantage). Previous research documents a reduction in timed interval variability when two effectors time instead of one. In addition, interval variability decreases with multiple sources of feedback. To date, however, no research has explored the separate roles of feedback and internal timing on the bimanual advantage. We evaluated the bimanual advantage in a task that does not utilise an internal clock (circle drawing). Participants performed both unimanual and bimanual timing while tapping or drawing circles. Both tasks were performed with and without tactile feedback at the timing goal. We document reduced bimanual timing variability only for tasks that utilise internal clock-like timing (tapping). We also document reduced timing variability for timing with greater sensory feedback (tactile vs no-tactile feedback tapping). We conclude that internal clock mechanisms are necessary for bimanual advantage to occur, but that multiple sources of feedback can also serve to improve internal timing, which ties together current theories of bimanual advantage.
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Ghacibeh, Georges A., Ravi Mirpuri, Valeria Drago, Yong Jeong, Kenneth M. Heilman, and William J. Triggs. "Ipsilateral motor activation during unimanual and bimanual motor tasks." Clinical Neurophysiology 118, no. 2 (2007): 325–32. http://dx.doi.org/10.1016/j.clinph.2006.10.003.
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Maslovat, Dana, Faven Teku, Victoria Smith, Neil M. Drummond, and Anthony N. Carlsen. "Bimanual but not unimanual finger movements are triggered by a startling acoustic stimulus: evidence for increased reticulospinal drive for bimanual responses." Journal of Neurophysiology 124, no. 6 (2020): 1832–38. http://dx.doi.org/10.1152/jn.00309.2020.
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The relative contributions of reticulospinal and corticospinal pathways to movement initiation are relatively unknown but appear to depend on the involved musculature. Here, we show that unimanual finger movements, which are predominantly initiated via corticospinal pathways, are not triggered at short latency by a startling acoustic stimulus (SAS), while bimanual finger movements are triggered by the SAS. This distinction is attributed to increased reticulospinal drive for bilateral responses.
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Ranganathan, Rajiv, Rani Gebara, Michael Andary, and Jim Sylvain. "Chronic stroke survivors show task-dependent modulation of motor variability during bimanual coordination." Journal of Neurophysiology 121, no. 3 (2019): 756–63. http://dx.doi.org/10.1152/jn.00218.2018.
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Stroke often results in hemiparesis, leaving one side of the body “affected” relative to the other side. Prior research has shown that the affected arm has higher variability; however, the extent to which this variability can be modulated is unclear. Here we used a shared bimanual task to examine the degree to which participants could modulate the variability in the affected arm after stroke. Participants with chronic stroke ( n = 11) and age-matched controls ( n = 11) performed unimanual and bimanual reaching movements to move a cursor on a screen to different targets. In the unimanual condition, the cursor was controlled only by the movement of a single arm, whereas, in the bimanual condition, the cursor position was “shared” between the two arms by using a weighted average of the two hand positions. Unknown to the participants, we altered the weightings of the affected and unaffected arms to cursor motion and examined how the movement variability on each arm changed depending on its contribution to the task. Results showed that stroke survivors had higher movement variability on the affected arm; however, like age-matched controls, they were able to modulate the variability in both the affected and unaffected arms according to the weighting condition. Specifically, as the weighting on a particular arm increased (i.e., it became more important to the task), the movement variability decreased. These results show that stroke survivors are capable of modulating variability depending on the task context, and this feature may potentially be exploited for rehabilitation paradigms. NEW & NOTEWORTHY We show that chronic stroke survivors, similar to age-matched controls, are able to modulate variability in their affected and unaffected limbs in redundant bimanual tasks as a function of how these limbs contribute to the task. Specifically, in both affected and unaffected limbs, the variability of the limb increases as its contribution to the task decreases. This feature may potentially be exploited in rehabilitation paradigms using bimanual tasks.
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Mutha, Pratik K., and Robert L. Sainburg. "Shared Bimanual Tasks Elicit Bimanual Reflexes During Movement." Journal of Neurophysiology 102, no. 6 (2009): 3142–55. http://dx.doi.org/10.1152/jn.91335.2008.
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Previous research has suggested distinct predictive and reactive control mechanisms for bimanual movements compared with unimanual motion. Recent studies have extended these findings by demonstrating that movement corrections during bimanual movements might differ depending on whether or not the task is shared between the arms. We hypothesized that corrective responses during shared bimanual tasks recruit bilateral rapid feedback mechanisms such as reflexes. We tested this hypothesis by perturbing one arm as subjects performed uni- and bimanual movements. Movements were made in a virtual-reality environment in which hand position was displayed as a cursor on a screen. During bimanual motion, we provided cursor feedback either independently for each arm (independent-cursor) or such that one cursor was placed at the average location between the arms (shared-cursor). On random trials, we applied a 40 N force pulse to the right arm 100 ms after movement onset. Our results show that while reflex responses were rapidly elicited in the perturbed arm, electromyographic activity remained close to baseline levels in the unperturbed arm during the independent-cursor trials. In contrast, when the cursor was shared between the arms, reflex responses were reduced in the perturbed arm and were rapidly elicited in the unperturbed arm. Our results thus suggest that when both arms contribute to achieving the task goal, reflex responses are bilaterally elicited in response to unilateral perturbations. These results agree with and extend recent suggestions that bimanual feedback control might be modified depending on task context.
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Naito, Eiichi, Filip Scheperjans, Simon B. Eickhoff, et al. "Human Superior Parietal Lobule Is Involved in Somatic Perception of Bimanual Interaction With an External Object." Journal of Neurophysiology 99, no. 2 (2008): 695–703. http://dx.doi.org/10.1152/jn.00529.2007.
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The question of how the brain represents the spatial relationship between the own body and external objects is fundamental. Here we investigate the neural correlates of the somatic perception of bimanual interaction with an external object. A novel bodily illusion was used in conjunction with functional magnetic resonance imaging (fMRI). During fMRI scanning, seven blindfolded right-handed participants held a cylinder between the palms of the two hands while the tendon of the right wrist extensor muscle was vibrated. This elicited a kinesthetic illusion that the right hand was flexing and that the hand-held cylinder was shrinking from the right side. As controls, we vibrated the skin surface over the nearby bone beside the tendon or vibrated the tendon when the hands were not holding the object. Neither control condition elicited this illusion. The significance of the illusion was also confirmed in supplementary experiments outside the scanner on another 16 participants. The “bimanual shrinking-object illusion” activated anterior parts of the superior parietal lobule (SPL) bilaterally. This region has never been activated in previous studies on unimanual hand or hand-object illusion. The illusion also activated left-hemispheric brain structures including area 2 and inferior parietal lobule, an area related to illusory unimanual hand-object interaction between a vibrated hand and a touched object in our previous study. The anterior SPL seems to be involved in the somatic perception of bimanual interaction with an external object probably by computing the spatial relationship between the two hands and a hand-held object.
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Gruevski, Kristina M., Joanne N. Hodder, and Peter J. Keir. "Upper Extremity Muscle Activity During In-Phase and Anti-Phase Continuous Pushing Tasks." Human Factors: The Journal of the Human Factors and Ergonomics Society 59, no. 7 (2017): 1066–77. http://dx.doi.org/10.1177/0018720817714367.
Full textAbstract:
Objective: To determine the effect of anti-phase, in-phase bimanual and unimanual simulated industrial pushing tasks and frequency on upper extremity muscle activity. Background: Research investigating symmetrical (in-phase) and asymmetrical (anti-phase) pushing exertions is limited despite a high prevalence in industry. Methods: Fifteen female participants completed five pushing tasks using a dual handle apparatus at three frequencies: 15 cycles per minute (cpm), 30 cpm, and self-selected. Tasks included two bimanual symmetrical pushes (constrained and unconstrained), two bimanual asymmetrical pushes (reciprocating and continuous), and one right unimanual push. Surface electromyography (EMG) from the right anterior, middle, and posterior deltoid (AD, MD, and PD); right and left trapezius (RT and LT); right pectoralis major (PM); and right and left external obliques (REO and LEO) was collected and normalized to maximum voluntary effort. Results: There was a task by frequency interaction in the AD, MD, PD, and RT ( p < .005), where activity in AD, MD, and PD was highest in the continuous task at 15 cpm, but activity was similar across task in 30 cpm and self-selected. Muscle activity coefficient of variation was lowest during continuous task across all frequencies. Conclusion: Continuous, anti-phase pushes and constrained, in-phase pushes had the highest muscle activity demands and the least amount of variability in muscle activity and therefore may present the greatest risk of injury. Application: Anti-phase pushing is known to have a greater cognitive demand, and this study demonstrated that it also has a greater physical demand when performed continuously.
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Poitras, Isabelle, Ophélie Martinie, Maxime T. Robert, Alexandre Campeau-Lecours, and Catherine Mercier. "Impact of Sensory Deficits on Upper Limb Motor Performance in Individuals with Cerebral Palsy: A Systematic Review." Brain Sciences 11, no. 6 (2021): 744. http://dx.doi.org/10.3390/brainsci11060744.
Full textAbstract:
People living with cerebral palsy (CP) exhibit motor and sensory impairments that affect unimanual and bimanual functions. The importance of sensory functions for motor control is well known, but the association between motor and sensory functions remains unclear in people living with CP. The objective of this systematic review was to characterize the relationship between sensory deficits and upper limb motor function in individuals living with CP. Methods: Five databases were screened. The inclusion criteria were: (1) including people living with CP, (2) reporting measurements of upper limb motor and sensory functions. A qualitative analysis of the studies’ level of evidence was done. Results: Thirty-three articles were included. Twenty-five articles evaluated tactile functions, 10 proprioceptive functions and 7 visual functions; 31 of the articles reported on unimanual functions and 17 of them reported on bimanual functions. Tactile functions showed a moderate to high association; it was not possible to reach definitive conclusions for proprioceptive and visual functions. Conclusions: The heterogeneity of the results limits the ability to draw definitive conclusions. Further studies should aim to perform more comprehensive assessments of motor and sensory functions, to determine the relative contribution of various sensory modalities to simple and more complex motor functions.
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Pinet, Svetlana, Gary S. Dell, and F. Xavier Alario. "Tracking Keystroke Sequences at the Cortical Level Reveals the Dynamics of Serial Order Production." Journal of Cognitive Neuroscience 31, no. 7 (2019): 1030–43. http://dx.doi.org/10.1162/jocn_a_01401.
Full textAbstract:
Response selection is often studied by examining single responses, although most actions are performed within an overarching sequence. Understanding processes that order and execute items in a sequence is thus essential to give a complete picture of response selection. In this study, we investigate response selection by comparing single responses and response sequences as well as unimanual and bimanual sequences. We recorded EEG while participants were typing one- or two-keystroke sequences. Irrespective of stimulus modality (visual or auditory), response-locked analysis revealed distinct contralateral and ipsilateral components previously associated with activation and inhibition of alternative responses. Unimanual sequences exhibited a similar activation/inhibition pattern as single responses, but with the activation component of the pattern expressed more strongly, reflecting the fact that the hand will be used for two strokes. In contrast, bimanual sequences were associated with successive activation of each of the corresponding motor cortices controlling each keystroke and no traceable inhibitory component. In short, the activation component of the two-keystroke sequence EEG pattern can be understood from the addition of activation components of single-stroke sequences; the inhibition of the hand not being used is only evidenced when that hand is not planned for the next stroke.
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Nyyssönen, Taneli, Seppo Helle, Teijo Lehtonen, and Jouni Smed. "A Comparison of One- and Two-Handed Gesture User Interfaces in Virtual Reality—A Task-Based Approach." Multimodal Technologies and Interaction 8, no. 2 (2024): 10. http://dx.doi.org/10.3390/mti8020010.
Full textAbstract:
This paper presents two gesture-based user interfaces which were designed for a 3D design review in virtual reality (VR) with inspiration drawn from the shipbuilding industry’s need to streamline and make their processes more sustainable. The user interfaces, one focusing on single-hand (unimanual) gestures and the other focusing on dual-handed (bimanual) usage, are tested as a case study using 13 tasks. The unimanual approach attempts to provide a higher degree of flexibility, while the bimanual approach seeks to provide more control over the interaction. The interfaces were developed for the Meta Quest 2 VR headset using the Unity game engine. Hand-tracking (HT) is utilized due to potential usability benefits in comparison to standard controller-based user interfaces, which lack intuitiveness regarding the controls and can cause more strain. The user interfaces were tested with 25 test users, and the results indicate a preference toward the one-handed user interface with little variation in test user categories. Additionally, the testing order, which was counterbalanced, had a statistically significant impact on the preference and performance, indicating that learning novel interaction mechanisms requires an adjustment period for reliable results. VR sickness was also strongly experienced by a few users, and there were no signs that gesture controls would significantly alleviate it.