Bimanual Motor Research Articles

Discovering the sense of touch: protocol for a randomised controlled trial examining the efficacy of a somatosensory discrimination intervention for children with hemiplegic cerebral palsy

BackgroundOf children with hemiplegic cerebral palsy, 75% have impaired somatosensory function, which contributes to learned non-use of the affected upper limb. Currently, motor learning approaches are used to improve upper-limb motor skills in these children, but few studies have examined the effect of any intervention to ameliorate somatosensory impairments. Recently, Sense© training was piloted with a paediatric sample, seven children with hemiplegic cerebral palsy, demonstrating statistically and clinically significant change in limb position sense, goal performance and bimanual hand-use. This paper describes a protocol for a Randomised Controlled Trial of Sense© for Kids training, hypothesising that its receipt will improve somatosensory discrimination ability more than placebo (dose-matched Goal Directed Therapy via Home Program). Secondary hypotheses include that it will alter brain activation in somatosensory processing regions, white-matter characteristics of the thalamocortical tracts and improve bimanual function, activity and participation more than Goal Directed Training via Home Program.Methods and designThis is a single blind, randomised matched-pair, placebo-controlled trial. Participants will be aged 6–15 years with a confirmed description of hemiplegic cerebral palsy and somatosensory discrimination impairment, as measured by the sense©_assess Kids. Participants will be randomly allocated to receive 3h a week for 6 weeks of either Sense© for Kids or Goal Directed Therapy via Home Program. Children will be matched on age and severity of somatosensory discrimination impairment. The primary outcome will be somatosensory discrimination ability, measured by sense©_assess Kids score. Secondary outcomes will include degree of brain activation in response to a somatosensory task measured by functional MRI, changes in the white matter of the thalamocortical tract measured by diffusion MRI, bimanual motor function, activity and participation.DiscussionThis study will assess the efficacy of an intervention to increase somatosensory discrimination ability in children with cerebral palsy. It will explore clinically important questions about the efficacy of intervening in somatosensation impairment to improve bimanual motor function, compared with focusing on motor impairment directly, and whether focusing on motor impairment alone can affect somatosensory ability.Trial registrationThis trial is registered with the Australian New Zealand Clinical Trials Registry, registration number: ACTRN12618000348257. World Health Organisation universal trial number: U1111–1210-1726.

Parietal, but Not Motor Cortex, HD-atDCS Deteriorates Learning Transfer of a Complex Bimanual Coordination Task

The non-invasive brain stimulation technique, transcranial direct current stimulation (tDCS), is thought to alter cortical excitability and induce neuroplastic changes. When anodal tDCS is applied in association with motor practice, it has frequently been shown to modulate motor performance and motor skill learning. However, the majority of evidence comes from research on tDCS effects on unimanual motor tasks. Despite the abundance of activities of daily life that require complex bimanual motor skills, systematic explorations of the effects of tDCS on the modulation of bimanual motor performance and learning remain sparse. Therefore, the objective of this study was to investigate the effects of anodal high-definition tDCS (HD-atDCS) on motor performance, motor skill learning, and transfer of a complex bimanual coordination task. Twenty-seven healthy right-handed volunteers, divided into three groups, participated in this double-blind study on five separate days. Between a pre- and posttest, participants practiced the bimanual task on 3 days (training days) and concurrently received either bilateral HD-atDCS over the primary motor cortex, parietal cortex, or a sham stimulation. On the fourth day, a retention test was performed, and a second took place after additional 5 to 7 days. Neither motor nor parietal HD-atDCS improved the performance or learning of the bimanual coordination task. Unexpectedly, we found a detrimental effect of parietal HD-atDCS on a transfer task, which was most pronounced during consolidation. Therefore, further research is needed to prove the potential of tDCS to modulate bimanual motor skills and elaborate optimized stimulation protocols for application, such as in the recovery of neurological impairments of the upper limbs.

Simon-Task Reveals Balanced Visuomotor Control in Experienced Video-Game Players

Both short and long-term video-game play may result in superior performance on visual and attentional tasks. To further these findings, we compared the performance of experienced male video-game players (VGPs) and non-VGPs on a Simon-task. Experienced-VGPs began playing before the age of 10, had a minimum of 8 years of experience and a minimum play time of over 20 h per week over the past 6 months. Our results reveal a significantly reduced Simon-effect in experienced-VGPs relative to non-VGPs. However, this was true only for the right-responses, which typically show a greater Simon-effect than left-responses. In addition, experienced-VGPs demonstrated significantly quicker reaction times and more balanced left-versus-right-hand performance than non-VGPs. Our results suggest that experienced-VGPs can resolve response-selection conflicts more rapidly for right-responses than non-VGPs, and this may in part be underpinned by improved bimanual motor control.

Using Robotics to Quantify Impairments in Sensorimotor Ability, Visuospatial Attention, Working Memory, and Executive Function After Traumatic Brain Injury.

To investigate the use of a robotic assessment tool to quantify sensorimotor, visuospatial attention, and executive function impairments in individuals with traumatic brain injury (TBI). Foothills Hospital (Calgary, Canada). Twenty-three subjects with first-time TBI in the subacute to chronic phase participated in this study. Normative data were collected from 275 to 494 neurologically intact control subjects for each robotic task. A prospective observational case series. Subjects with TBI completed brief clinical cognitive and motor assessments followed by robotic assessments of upper limb reaching, position sense, bimanual motor ability, attention, and visuospatial skills. Scores of subjects with TBI were compared with normative data. Robotic task performance was computed for each subject on each task, as well as performance on specific task parameters. Clinical assessments included the Montreal Cognitive Assessment, Fugl-Meyer upper extremity assessment, and Purdue Peg Board. Subjects with TBI demonstrated a variety of deficits on robotic tasks. The proportion of TBI subjects who were significantly different from controls ranged from 36% (dominant arm reaching) to 60% (bimanual object hitting task). Robotic measures allowed us to quantify a range of impairments specific to each subject, and offer an objective tool with which to examine these abilities after TBI.

S149. Improved bimanual control in elderly after motor cortex stimulation

Introduction Accompanying the natural advancing of age is a decline in cognitive and motor functions, which may be the result of altered neuroplasticity, due to changes in synaptic function and neurotransmission. Successful performance of routine, but complex motor tasks such as bimanual movements may require optimal synchronization of motor cortical areas, which decline with ageing. On the other hand, recent work has shown that transcranial direct current stimulation (tDCS) may be a useful tool to restitute these altered mechanisms, and improve performance of motor skills. Presently, we address the question of identifying physiological markers of age-related differences during acquisition of new bimanual motor control tasks, based on induced oscillatory changes, using EEG. Second, we assess whether performance of complex bimanual skills can be improved in the elderly using tDCS. Methods Experiment 1 : 43 healthy subjects (21 elderly) performed the bimanual tracking task (BTT), which is a complex task requiring multiple cognitive domains, as well as the skilled use of in-phase and anti-phase movements, at various frequencies. Three blocks of the task were performed (180 total trials) while EEG was recorded to measure task-induced power changes. Experiment 2 : An additional 40 subjects (20 elderly) were recruited for evaluating whether right M1 anodal tDCS (1.0 mA, 20 min) may improve performance in the task, particularly in the non-dominant left hand. The study was double-blinded, sham-controlled, and employed a randomized crossover design in order to assess tDCS-induced performance and task-induced synchronization differences between young and elderly groups. Results Experiment 1: Overall task performance in younger subjects was more accurate than in elderly. Younger subjects showed significantly stronger desynchronization in the mu and beta band, whereas older subjects showed greater gamma band activity in motor cortical areas. In addition, these patterns were also found to correlate inter-individually with accurate performance in the task. Experiment 2: ANOVA revealed a main effect of stimulation, which was significant between active and sham tDCS conditions in the elderly but not in young. Further exploratory analyses revealed significant improvements in both left and right hand coordination in active stimulation conditions for both groups of subjects, with the greatest improvement found in left-hand dominant motor movements in the elderly group. Conclusion We show that both task-induced oscillatory synchronization and inter-limb kinematics underlying bimanual motor coordination are different between the young and elderly. Further, a single session of tDCS applied to the motor cortex could significantly improve bimanual performance in the elderly. Although further studies are needed to optimize tDCS parameters for enhanced and prolonged effects, tDCS may be a viable tool in restituting the learning of complex motor functions in the aging or other vulnerable populations.

Brain Oscillatory and Hemodynamic Activity in a Bimanual Coordination Task Following Transcranial Alternating Current Stimulation (tACS): A Combined EEG-fNIRS Study.

Motor control is associated with synchronized oscillatory activity at alpha (8–12 Hz) and beta (12–30 Hz) frequencies in a cerebello-thalamo-cortical network. Previous studies demonstrated that transcranial alternating current stimulation (tACS) is capable of entraining ongoing oscillatory activity while also modulating motor control. However, the modulatory effects of tACS on both motor control and its underlying electro- and neurophysiological mechanisms remain ambiguous. Thus, the purpose of this study was to contribute to gathering neurophysiological knowledge regarding tACS effects by investigating the after-effects of 10 Hz tACS and 20 Hz tACS at parietal brain areas on bimanual coordination and its concurrent oscillatory and hemodynamic activity. Twenty-four right-handed healthy volunteers (12 females) aged between 18 and 30 (M = 22.35 ± 3.62) participated in the study and performed a coordination task requiring bimanual movements. Concurrent to bimanual motor training, participants received either 10 Hz tACS, 20 Hz tACS or a sham stimulation over the parietal cortex (at P3/P4 electrode positions) for 20 min via small gel electrodes (3,14 cm2 Ag/AgCl, amperage = 1 mA). Before and three time-points after tACS (immediately, 30 min and 1 day), bimanual coordination performance was assessed. Oscillatory activities were measured by electroencephalography (EEG) and hemodynamic changes were examined using functional near-infrared spectroscopy (fNIRS). Improvements of bimanual coordination performance were not differently between groups, thus, no tACS-specific effect on bimanual coordination performance emerged. However, physiological measures during the task revealed significant increases in parietal alpha activity immediately following 10 Hz tACS and 20 Hz tACS which were accompanied by significant decreases of Hboxy concentration in the right hemispheric motor cortex compared to the sham group. Based on the physiological responses, we conclude that tACS applied at parietal brain areas provoked electrophysiological and hemodynamic changes at brain regions of the motor network which are relevant for bimanual motor behavior. The existence of neurophysiological alterations immediately following tACS, especially in the absence of behavioral effects, are elementary for a profound understanding of the mechanisms underlying tACS. The lack of behavioral modifications strengthens the need for further research on tACS effects on neurophysiology and behavior using combined electrophysiological and neuroimaging methods.

Effects of tDCS on Bimanual Motor Skills: A Brief Review.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that allows the modulation of cortical excitability as well as neuroplastic reorganization using a weak constant current applied through the skull on the cerebral cortex. TDCS has been found to improve motor performance in general and motor learning in particular. However, these effects have been reported almost exclusively for unimanual motor tasks such as serial reaction time tasks, adaptation tasks, or visuo-motor tracking. Despite the importance of bimanual actions in most activities of daily living, only few studies have investigated the effects of tDCS on bimanual motor skills. The objectives of this review article are: (i) to provide a concise overview of the few existing studies in this area; and (ii) to discuss the effects of tDCS on bimanual motor skills in healthy volunteers and patients suffering from neurological diseases. Despite considerable variations in stimulation protocols, the bimanual tasks employed, and study designs, the data suggest that tDCS has the potential to enhance bimanual motor skills. The findings imply that the effects of tDCS vary with task demands, such as complexity and the level of expertise of the participating volunteers. Nevertheless, optimized stimulation protocols tailored to bimanual tasks and individual performance considering the underlying neural substrates of task execution are required in order to probe the effectiveness of tDCS in greater detail, thus creating an opportunity to support motor recovery in neuro-rehabilitation.

Hand-Arm Bimanual Intensive Therapy Improves Prefrontal Cortex Activation in Children With Hemiplegic Cerebral Palsy.

To determine the changes in the prefrontal cortical (PFC) activation following hand-arm bimanual intensive therapy (HABIT) in children with hemiplegic cerebral palsy (HCP). Nine children with HCP and 15 children who were developing typically participated in the study. Children with HCP received 50 hours of HABIT. We assessed pre- and post-HABIT PFC activation using functional near-infrared spectroscopy neuroimaging. Bimanual coordination and motor task performance were assessed using the Assisting Hand Assessment (AHA), the average number of shapes matched, the shape matching errors, the reaction time, the 9-hole peg test, and the box and blocks test. The PFC activation decreased following HABIT and became similar to what was seen in the children who were developing typically. Post-HABIT PFC activation improvements paralleled with the improvements seen in the AHA and the behavioral outcomes. HABIT potentially improves the PFC's involvement in the action planning of the upper extremity movements in children with HCP.

O-2-40. Comparisons of functional EEG network during performing different bimanual motor tasks using graph theoretical analysis

Graph theoretical approach is emerging as a powerful tool for analyzing brain functional network. To compare functional electroencephalography (EEG) network between inphase and anti-phase of bimanual hand movement, 10 healthy subjects were carried out experiments. In the clustering coefficient (CC), the alpha band of dominant motor area (C3) and the beta band of non-dominant motor area (C4) during anti-phase movement were higher than those of in-phase movement. In the betweenness centrality (BC), the alpha band of C3 during anti-phase movement was lower than those of in-phase movement. On the other hand, the gamma band of C4 during anti-phase movement was higher than those of in-phase movement. Additional analysis revealed that patient with stroke in the left middle cerebral artery infraction tended to low CC both movement and low BC during anti-phase movement. Our findings suggest that task-specific functional network alterations reflect on these graph theoretical parameters. In conclusion, the graph theoretical analysis applied to EEG network during bimanual hand movement has a potential to evaluate the brain network function.

Interhemispheric Cortical Inhibition Is Reduced in Young Adults With Developmental Coordination Disorder.

While the etiology of developmental coordination disorder (DCD) is yet to be established, brain-behavior modeling provides a cogent argument that neuropathology may subserve the motor difficulties typical of DCD. We argue that a number of the core behavioral features of the DCD profile (such as poor surround inhibition, compromised motor inhibition, and the presence of mirror movements) are consistent with difficulties regulating inhibition within the primary motor cortex (M1). This study aimed to be the first account of the integrity of cortical inhibition in motor cortices in DCD. The sample consisted of eight adults with DCD aged (18-30 years) and 10 aged matched neurotypical controls. Participants received a common battery of single and paired-pulse transcranial magnetic stimulation from which a series of neurophysiological measures classically used to measure intra- [e.g., short-interval cortical inhibition (SICI), long-interval cortical inhibition (LICI), and cortical silent period] and inter hemispheric [e.g., ipsilateral silent period (ISP)] cortical inhibition of the M1 at rest were recorded. While no group differences were observed for any measure of intrahemispheric cortical inhibition, individuals with DCD demonstrated significantly reduced interhemispheric cortical inhibition relative to controls, shown by consistently lower ISPratios. Our findings are consistent with the view that regulation of cortical inhibition of M1 activity may be atypical in individuals with DCD, indicating differential GABAergic operation. This effect, however, appears to be select to cortical inhibition. Importantly, our data support the notion that reduced interhemispheric M1 cortical inhibition may at least partly explain commonly reported difficulties with bimanual motor control in DCD. The neurochemical implications and limitations of this evidence will be discussed.

Changes in Tactile Function During Intensive Bimanual Training in Children With Unilateral Spastic Cerebral Palsy.

Recently, an intensive bimanual intervention using sensory enriched materials resulted in improved tactile function in children with unilateral spastic cerebral palsy (USCP), raising the question of whether the observed tactile function improvement was due to the sensory enriched environment or the bimanual intervention per se. The present study investigates whether a bimanual intensive intervention improves tactile function. Nineteen children with USCP received 90 hours of bimanual training without enriched environment. Primary outcomes: Manual Form Perception Test/MFPT, Grating Orientation Task/GOT. Children were assessed before, after the training, and at the 4-month follow-up. Significant improvements were observed in MFPT for the more affected hand ( P = .015). Larger stereognosis/MFPT improvements correlated with poorer baseline motor function. Intensive bimanual training alone was sufficient to improve stereognosis, though no improvement in GOT was observed. Present and previously published findings suggest that environmental tactile enrichment incorporated into a bimanual motor training may be needed to improve spatial discrimination/GOT in children with USCP.

Coherence and interlimb force control: Effects of visual gain

Neural coupling across hemispheres and homologous muscles often appears during bimanual motor control. Force coupling in a specific frequency domain may indicate specific bimanual force coordination patterns. This study investigated coherence on pairs of bimanual isometric index finger force while manipulating visual gain and task asymmetry conditions. We used two visual gain conditions (low and high gain = 8 and 512 pixels/N), and created task asymmetry by manipulating coefficient ratios imposed on the left and right index finger forces (0.4:1.6; 1:1; 1.6:0.4, respectively). Unequal coefficient ratios required different contributions from each hand to the bimanual force task resulting in force asymmetry. Fourteen healthy young adults performed bimanual isometric force control at 20% of their maximal level of the summed force of both fingers. We quantified peak coherence and relative phase angle between hands at 0–4, 4–8, and 8–12 Hz, and estimated a signal-to-noise ratio of bimanual forces. The findings revealed higher peak coherence and relative phase angle at 0–4 Hz than at 4–8 and 8–12 Hz for both visual gain conditions. Further, peak coherence and relative phase angle values at 0–4 Hz were larger at the high gain than at the low gain. At the high gain, higher peak coherence at 0–4 Hz collapsed across task asymmetry conditions significantly predicted greater signal-to-noise ratio. These findings indicate that a greater level of visual information facilitates bimanual force coupling at a specific frequency range related to sensorimotor processing.

Two Processes in Early Bimanual Motor Skill Learning.

Most daily activities are bimanual and their efficient performance requires learning and retention of bimanual coordination. Despite in-depth knowledge of the various stages of motor skill learning in general, how new bimanual coordination control policies are established is still unclear. We designed a new cooperative bimanual task in which subjects had to move a cursor across a complex path (a circuit) as fast and as accurately as possible through coordinated bimanual movements. By looking at the transfer of the skill between different circuits and by looking at training with varying circuits, we identified two processes in early bimanual motor learning. Loss of performance due to the switch in circuit after 15 min of training amounted to 20%, which suggests that a significant portion of improvements in bimanual performance is specific to the used circuit (circuit-specific skill). In contrast, the loss of performance due to the switch in circuit was 5% after 4 min of training. This suggests that learning the new bimanual coordination control policy dominates early in the training and is independent of the used circuit. Finally, switching between two circuits throughout training did not affect the early stage of learning (i.e., the first few minutes), but did affect the later stage. Together, these results suggest that early bimanual motor skill learning includes two different processes. Learning the new bimanual coordination control policy predominates in the first minutes whereas circuit-specific skill improvements unfold later in parallel with further improvements in the bimanual coordination control policy.

Investigating bimanual motor performance on daily bimanual tasks in children with hemiplegic cerebral palsy

Background: Most activities of daily living require the cooperative use of both hands. Children with hemiplegic cerebral palsy (CP) usually have difficulties in bimanual coordination, which would further influence their daily function. However, there was limited research investigating the differences between performance of affected hand and unaffected hand in daily bilateral tasks.

Can intensive unimanual and bimanual motor interventions improve visuospatial performance in children with unilateral spastic cerebral palsy? A randomized controlled trial

Can intensive unimanual and bimanual motor interventions improve visuospatial performance in children with unilateral spastic cerebral palsy? A randomized controlled trial

Advantages of melodic over rhythmic movement sonification in bimanual motor skill learning

An important question for skill acquisition is whether and how augmented feedback can be designed to improve the learning of complex skills. Auditory information triggered by learners’ actions, movement sonification, can enhance learning of a complex bimanual coordination skill, specifically polyrhythmic bimanual shape tracing. However, it is not clear whether the coordination of polyrhythmic sequenced movements is enhanced by auditory-specified timing information alone or whether more complex sound mappings, such as melodic sonification, are necessary. Furthermore, while short-term retention of bimanual coordination performance has been shown with movement sonification training, longer term retention has yet to be demonstrated. In the present experiment, participants learned to trace a diamond shape with one hand while simultaneously tracing a triangle with the other to produce a sequenced 4:3 polyrhythmic timing pattern. Two groups of participants received real-time auditory feedback during training: melodic sonification (individual movements triggered a separate note of a melody) and rhythmic sonification (each movement triggered a percussive sound), while a third control group received no augmented feedback. Task acquisition and performance in immediate retention were superior in the melodic sonification group as compared to the rhythmic sonification and control group. In a 24-h retention phase, a decline in performance in the melodic sonification group was reversed by brief playback of the target pattern melody. These results show that melodic sonification of movement can provide advantages over augmented feedback which only provides timing information by better structuring the sequencing of timed actions, and also allow recovery of complex target patterns of movement after training. These findings have important implications for understanding the role of augmented perceptual information in skill learning, as well as its application to real-world training or rehabilitation scenarios.

Effects of High-Definition Anodal Transcranial Direct Current Stimulation Applied Simultaneously to Both Primary Motor Cortices on Bimanual Sensorimotor Performance.

Many daily activities, such as tying one’s shoe laces, opening a jar of jam or performing a free throw in basketball, require the skillful coordinated use of both hands. Even though the non-invasive method of transcranial direct current stimulation (tDCS) has been repeatedly shown to improve unimanual motor performance, little is known about its effects on bimanual motor performance. More knowledge about how tDCS may improve bimanual behavior would be relevant to motor recovery, e.g., in persons with bilateral impairment of hand function. We therefore examined the impact of high-definition anodal tDCS (HD-atDCS) on the performance of a bimanual sequential sensorimotor task. Thirty-two volunteers (age M = 24.25; SD = 2.75; 14 females) participated in this double-blind study and performed sport stacking in six experimental sessions. In sport stacking, 12 specially designed cups must be stacked (stacked up) and dismantled (stacked down) in predefined patterns as fast as possible. During a pretest, posttest and follow-up test, two sport stacking formations (3-6-3 stack and 1-10-1 stack) were performed. Between the pretest and posttest, all participants were trained in sport stacking with concurrent brain stimulation for three consecutive days. The experimental group (STIM-M1) received HD-atDCS over both primary motor cortices (M1), while the control group received a sham stimulation (SHAM). Three-way analysis of variance (ANOVA) revealed a significant main effect of TIME and a significant interaction of TIME × GROUP. No significant effects were found for GROUP, nor for the three-way interaction of TIME × GROUP × FORMATION. Further two-way ANOVAs showed a significant main effect of TIME and a non-significant main effect for GROUP in both sport stacking formations. A significant interaction between TIME × GROUP was found only for the 3-6-3 formation, indicating superior performance gains for the experimental group (STIM-M1). To account and control for baseline influences on the outcome measurements, ANCOVAs treating pretest scores as covariates revealed a significant effect of the stimulation. From this, we conclude that bilateral HD-atDCS over both M1 improves motor performance in a bimanual sequential sensorimotor task. These results may indicate a beneficial use of tDCS for learning and recovery of bimanual motor skills.

Relative cortico-subcortical shift in brain activity but preserved training-induced neural modulation in older adults during bimanual motor learning

To study age-related differences in neural activation during motor learning, functional magnetic resonance imaging scans were acquired from 25 young (mean 21.5-year old) and 18 older adults (mean 68.6-year old) while performing a bimanual coordination task before (pretest) and after (posttest) a 2-week training intervention on the task. We studied whether task-related brain activity and training-induced brain activation changes differed between age groups, particularly with respect to the hyperactivation typically observed in older adults. Findings revealed that older adults showed lower performance levels than younger adults but similar learning capability. At the cerebral level, the task-related hyperactivation in parietofrontal areas and underactivation in subcortical areas observed in older adults were not differentially modulated by the training intervention. However, brain activity related to task planning and execution decreased from pretest to posttest in temporo-parieto-frontal areas and subcortical areas in both age groups, suggesting similar processes of enhanced activation efficiency with advanced skill level. Furthermore, older adults who displayed higher activity in prefrontal regions at pretest demonstrated larger training-induced performance gains. In conclusion, in spite of prominent age-related brain activation differences during movement planning and execution, the mechanisms of learning-related reduction of brain activation appear to be similar in both groups. Importantly, cerebral activity during early learning can differentially predict the amplitude of the training-induced performance benefit between young and older adults.

Learned control of inter-hemispheric connectivity: Effects on bimanual motor performance

Bimanual movements involve the interactions between both primary motor cortices. These interactions are assumed to involve phase-locked oscillatory brain activity referred to as inter-hemispheric functional coupling. So far, inter-hemispheric functional coupling has been investigated as a function of motor performance. These studies report mostly a negative correlation between the performance in motor tasks and the strength of functional coupling. However, correlation might not reflect a causal relationship. To overcome this limitation, we opted for an alternative approach by manipulating the strength of inter-hemispheric functional coupling and assessing bimanual motor performance as a dependent variable. We hypothesize that an increase/decrease of functional coupling deteriorates/facilitates motor performance in an out-of-phase bimanual finger-tapping task. Healthy individuals were trained to volitionally regulate functional coupling in an operant conditioning paradigm using real-time magnetoencephalography neurofeedback. During operant conditioning, two discriminative stimuli were associated with upregulation and downregulation of functional coupling. Effects of training were assessed by comparing motor performance prior to (pre-test) and after the training (post-test). Participants receiving contingent feedback learned to upregulate and downregulate functional coupling. Comparing motor performance, as indexed by the ratio of tapping speed for upregulation versus downregulation trials, no change was found in the control group between pre- and post-test. In contrast, the group receiving contingent feedback evidenced a significant decrease of the ratio implicating lower tapping speed with stronger functional coupling. Results point toward a causal role of inter-hemispheric functional coupling for the performance in bimanual tasks. Hum Brain Mapp 38:4353-4369, 2017. © 2017 Wiley Periodicals, Inc.

Shared and differentiated motor skill impairments in children with dyslexia and/or attention deficit disorder: From simple to complex sequential coordination.

Dyslexia and Attention deficit disorder (AD) are prevalent neurodevelopmental conditions in children and adolescents. They have high comorbidity rates and have both been associated with motor difficulties. Little is known, however, about what is shared or differentiated in dyslexia and AD in terms of motor abilities. Even when motor skill problems are identified, few studies have used the same measurement tools, resulting in inconstant findings. The present study assessed increasingly complex gross motor skills in children and adolescents with dyslexia, AD, and with both Dyslexia and AD. Our results suggest normal performance on simple motor-speed tests, whereas all three groups share a common impairment on unimanual and bimanual sequential motor tasks. Children in these groups generally improve with practice to the same level as normal subjects, though they make more errors. In addition, children with AD are the most impaired on complex bimanual out-of-phase movements and with manual dexterity. These latter findings are examined in light of the Multiple Deficit Model.