Posts Tagged cross education

[ARTICLE] Using Virtual Reality to Transfer Motor Skill Knowledge from One Hand to Another – Full Text


As far as acquiring motor skills is concerned, training by voluntary physical movement is superior to all other forms of training (e.g. training by observation or passive movement of trainee’s hands by a robotic device). This obviously presents a major challenge in the rehabilitation of a paretic limb since voluntary control of physical movement is limited. Here, we describe a novel training scheme we have developed that has the potential to circumvent this major challenge. We exploited the voluntary control of one hand and provided real-time movement-based manipulated sensory feedback as if the other hand is moving. Visual manipulation through virtual reality (VR) was combined with a device that yokes left-hand fingers to passively follow right-hand voluntary finger movements. In healthy subjects, we demonstrate enhanced within-session performance gains of a limb in the absence of voluntary physical training. Results in healthy subjects suggest that training with the unique VR setup might also be beneficial for patients with upper limb hemiparesis by exploiting the voluntary control of their healthy hand to improve rehabilitation of their affected hand.


Physical practice is the most efficient form of training. Although this approach is well established1, it is very challenging in cases where the basic motor capability of the training hand is limited2. To bypass this problem, a large and growing body of literature examined various indirect approaches of motor training.

One such indirect training approach uses physical practice with one hand to introduce performance gains in the other (non-practiced) hand. This phenomenon, known as cross-education (CE) or intermanual transfer, has been studied extensively 3,4,5,6,7,8,9 and used to enhance performance in various motor tasks 10,11,12. For instance, in sport skill settings, studies have demonstrated that training basketball dribbling in one hand transfers to increased dribbling capabilities in the other, untrained hand 13,14,15.

In another indirect approach, motor learning is facilitated through the use of visual or sensory feedback. In learning by observation, it has been demonstrated that significant performance gains can be obtained simply by passively observing someone else perform the task16,17,18,19,20. Similarly, proprioceptive training, in which the limb is passively moved, was also shown to improve performance on motor tasks 12,21,22,23,24,25,26.

Together, these lines of research suggest that sensory input plays an important role in learning. Here, we demonstrate that manipulating online sensory feedback (visual and proprioceptive) during physical training of one limb results in augmented performance gain in the opposite limb. We describe a training regime that yields optimal performance outcome in a hand, in the absence of its voluntary physical training. The conceptual novelty of the proposed method resides in the fact that it combines the three different forms of learning – namely, learning by observation, CE, and passive movement. Here we examined whether the phenomenon of CE, together with mirrored visual feedback and passive movement, can be exploited to facilitate learning in healthy subjects in the absence of voluntary physical movement of the training limb.

The concept in this setup differs from direct attempts to physically train the hand. At the methodological level – we introduce a novel setup including advanced technologies such as 3D virtual reality, and custom built devices that allow manipulating visual and proprioceptive input in a natural environmental setting. Demonstrating improved outcome using the proposed training has key consequences for real-world learning. For example, children use sensory feedback in a manner that is different from that of adults27,28,29 and in order to optimize motor learning, children may require longer periods of practice. The use of CE together with manipulated sensory feedback might reduce training duration. Furthermore, acquisition of sport skills might be facilitated using this kind of sophisticated training. Finally, this can prove beneficial for the development of a new approach for rehabilitation of patients with unilateral motor deficits such as stroke.[…]

Continue —> Using Virtual Reality to Transfer Motor Skill Knowledge from One Hand to Another

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[Thesis] The Effects of Limb Dominance on Cross-Education in a Four Week Resistance Training Program – Full Text PDF


Cross-education is known as the phenomenon of strength transfer from the trained side of the body to the untrained side of the body by unilateral resistance training. Research has shown that limb dominance has an effect on the amount of strength that is gained on the untrained side. Studies have found that there is a greater cross over effect in strength from the dominant side of the body to the non-dominant side of the body than vice versa. The present study examined this effect by taking 12 college females and splitting them into three groups: dominant training, nondominant training, and control group. The hypothesis was that the dominant training group would have a greater increase in peak grip strength in the untrained, non-dominant arm than the arm of the untrained, dominant group of the non-dominant training group. The dominant training group only trained their dominant arm with a hand dynamometer, while the non-dominant training group only trained their non-dominant arm with the same hand dynamometer. Both groups went through a 4-week, 13 sessions of grip strength training on the handy dynamometer.
They performed 3 sets of 6 maximal squeezes with a 2-minute rest in between sets. Pre-and post tests were taken of maximum grip strength squeeze. There was no significance difference in peak grip strength between the untrained arms of both groups. Also, there was no significance  difference in peak grip strength between the trained arms of both groups however there was a
trend in data in the untrained arm of the dominant training group showing a slight increase in  strength from baseline measurements. These findings do not directly support the hypothesis however, if the number of subjects’ value was greater, the trend in data in the dominant training group might have found significant effect from limb dominance.

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[Thesis] Clinicians’ Perspectives on Cross-Education in Stroke Rehabilitation – Full Text PDF


Purpose: Cross-education is a neural phenomenon where an untrained limb improves after unilateral training of the opposite homologous limb. It has been extensively studied in the healthy population and shows promise for post-stroke rehabilitation. Despite this promise, cross-education has not been adopted into clinical rehabilitation practice. Cross-education is contrary to current best practice for upper extremity post-stroke rehabilitation which is focused on training the affected limb. The objective of this study was to understand: current post-stroke upper extremity rehabilitation practice, clinician’s perspectives on cross-education, and facilitators and barriers to implementation of a cross-education intervention.

Methods: An Interpretive Description framework guided this study. Twenty- two occupational therapists and 2 physiotherapists were interviewed in 4 focus groups and 1 individual interview in a rehabilitation hospital and 3 acute care hospitals. After transcription, line-by-line coding was done by 2 investigators. A third investigator, who was not part of data collection, reviewed the process and agreed on the primary categories.

Results: Cross-education is antithetical yet promising was the lone theme which was reiterated in every data collection session. The primary theme was captured in 3 descriptive categories. The therapists described working in a (1) forced-use paradigm, yet they also described how that paradigm did not meet the needs of all of their patients. They recognized this as a (2) gap in current practice. They also hypothesized that (3) cross-education used as an adjunct could be quite effective within their current practice for specific patients. The primary theme weaves between the 3 categories.

Conclusions: Therapists perceived that cross-education would be most appropriate for patients with a severely impaired upper extremity. They suggested that educational materials for clinicians, patients, and patient families would be essential to the success of cross-education in order to explain training the less affected limb. This study provides important foundational information about clinician perspectives that will help transition cross-education into clinical stroke rehabilitation research and eventually practice.

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[ARTICLE] Neural Network Underlying Intermanual Skill Transfer in Humans- Full Text




Unimanual training also enhances performance in the untrained hand (cross-education)

Real-time manipulation of visual feedback enhances magnitude of cross-education
Yoking movement of untrained to trained hand further increases cross-education
Functional connectivity with SPL during training predicts cross-education


Physical practice with one hand results in performance gains of the other (un-practiced) hand, yet the role of sensory feedback and underlying neurophysiology is unclear. Healthy subjects learned sequences of finger movements by physical training with their right hand while receiving real-time movement-based visual feedback via 3D virtual reality devices as if their immobile left hand was training. This manipulation resulted in significantly enhanced performance gain with the immobile hand, which was further increased when left-hand fingers were yoked to passively follow right-hand voluntary movements. Neuroimaging data show that, during training with manipulated visual feedback, activity in the left and right superior parietal lobule and their degree of coupling with motor and visual cortex, respectively, correlate with subsequent left-hand performance gain. These results point to a neural network subserving short-term motor skill learning and may have implications for developing new approaches for learning and rehabilitation in patients with unilateral motor deficits.


It is common wisdom that “practice makes perfect”; however, what constitutes an optimal practice regime when learning a new skill is not clear. In the domain of motor skills, for example, when learning to dribble a basketball, physical training with the relevant effector obviously plays a crucial role. Nonetheless, research over the past decades has recognized that sensory feedback and mental imagery play a significant role in the learning process (Nyberg et al., 2006, Sigrist et al., 2013, Wolpert et al., 2011). In the case of vision, it has been shown that even in the absence of physical training, mere observation of someone else performing a motor task is sufficient to introduce significant gains in subsequent performance of the observer (Bird et al., 2005, Cross et al., 2009, Kelly et al., 2003, Mattar and Gribble, 2005, Nojima et al., 2015, Vogt and Thomaschke, 2007, Ossmy and Mukamel, 2016). Furthermore, passive limb movement has also been shown to facilitate learning (Beets et al., 2012, Darainy et al., 2013, Vahdat et al., 2014, Wong et al., 2012). Finally, physical training with one hand is known to result in significant performance gains in the opposite (untrained) hand—a phenomenon termed intermanual transfer or cross-education (Ruddy and Carson, 2013). Intermanual transfer has been reported as early as 1894, showing that unilateral strength training of a single limb increases the strength of the contralateral (untrained) homologous muscle group (Scripture et al., 1894). Since then, this effect has been demonstrated across multiple motor tasks (Anguera et al., 2007, Brass et al., 2001, Camus et al., 2009, Carroll et al., 2006, Criscimagna-Hemminger et al., 2003, Farthing et al., 2007, Lee et al., 2010, Malfait and Ostry, 2004, Perez and Cohen, 2008, Perez et al., 2007, Sainburg and Wang, 2002) and is suggested to occur through plastic changes in the brain that are not confined to the specific neural networks controlling the physically trained effector (e.g., plastic changes also in motor cortex ipsilateral to the active hand [Duque et al., 2008, Hortobágyi et al., 2003, Muellbacher et al., 2000, Obayashi, 2004]). Enhancing the behavioral effect of intermanual transfer and elucidating its underlying neural mechanism has important implications for rehabilitation of patients with unimanual deficits (Hendy et al., 2012, Ramachandran and Altschuler, 2009) in which direct training of the affected hand is difficult.

Given that visual input, physical training, and passive movement play a significant role in performance and intermanual transfer of motor skills, research in recent years examined the behavioral and neural consequences of training with manipulated visual feedback (Halsband and Lange, 2006). In particular, unimanual training with mirrored visual feedback (as if the opposite, passive hand, is training) has been shown to enhance transfer to the opposite hand and increase excitability of primary motor cortex (M1) ipsilateral to the physically trained hand (Garry et al., 2005, Hamzei et al., 2012, Nojima et al., 2012). Nonetheless, much less is known at the whole-brain network level and how inter-regional coupling during such training correlates with subsequent behavioral changes in performance. Additionally, at the behavioral level, the interaction between manipulated visual feedback and passive movement during training is unknown.

In the present study, we examined intermanual transfer using a novel setup employing 3D virtual reality (VR) devices to control visual feedback of finger movements during unimanual training of healthy adults (experiment 1). By using a novel device, we also examined whether the addition of passive finger movement of the non-physically training hand further enhances the intermanual transfer effect (experiment 2). Finally, we used whole-brain functional magnetic resonance imaging (fMRI) to probe the relevant brain regions engaged during such training and examined their degree of inter-regional coupling with respect to subsequent behavioral changes in performance of individual subjects (experiment 3).

Continue —>  Neural Network Underlying Intermanual Skill Transfer in Humans: Cell Reports

(A) Schematic illustration of one experimental condition. A unique sequence of five digits was presented together with a sketch of the mapped fingers (instructions). Subjects performed the sequence as accurately and rapidly as possible using their right hand (RH) and their left hand (LH) separately for initial evaluation of performance. Next, subjects were trained under a specific training type and finally repeated the evaluation test again. (B) Subjects wore a headset and motion sensitive gloves and received visual feedback of virtual hands. The VR devices allowed visual manipulation of online visual feedback. A camera mounted on the headset allowed embedding the virtual hands and subject’s view inside a natural environment. (C) Experiment 1 results. Physical training with the right hand while receiving online visual feedback as if the left hand is moving (RH-LH) resulted in highest left-hand performance gains relative to all other training conditions. Error bars indicate SEM across subjects. For condition acronyms, see Table 1.

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[ARTICLE] High-intensity, unilateral resistance training of a non-paretic muscle group increases active range of motion in a severely paretic upper extremity muscle group after stroke – Full Text PDF

Limited rehabilitation strategies are available for movement restoration when paresis is too severe following stroke. Previous research has shown that high-intensity resistance training of  one muscle group enhances strength of the homologous, contralateral muscle group in  neurologically-intact adults. How this “cross education” phenomenon might be exploited to  moderate severe weakness in an upper extremity muscle group after stroke is not well understood.

The primary aim of this study was to examine adaptations in force-generating  capacity of severely paretic wrist extensors resulting from high-intensity, dynamic contractions  of the non-paretic wrist extensors. A secondary, exploratory aim was to probe neural adaptations  in a subset of participants from each sample using a single-pulse, transcranial magnetic  stimulation protocol. Separate samples of neurologically-intact controls (n=7) and individuals >4 months post stroke (n=6) underwent 16 sessions of training. Following training, one-repetition  maximum of the untrained wrist extensors in the control group and active range of motion of the  untrained, paretic wrist extensors in the stroke group were significantly increased. No changes in  corticospinal excitability, intracortical inhibition or interhemispheric inhibition were observed in  control participants. Both stroke participants who underwent TMS testing, however, exhibited  increased voluntary muscle activation following the intervention. In addition, motor-evoked  potentials that were unobtainable prior to the intervention were readily elicited afterwards in a  stroke participant.

Results of this study demonstrate that high-intensity resistance training of a  non-paretic upper extremity muscle group can enhance voluntary muscle activation and force-  generating capacity of a severely paretic muscle group after stroke. There is also preliminary  evidence that corticospinal adaptations may accompany these gains.

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