Intermanual Coordination Research Articles

Visuomotor Coupling during Two-Handed Tasks: An Investigation of Bimanual and Intermanual Coordination

This study investigated previously observed differences in speed when completing a two-handed task using either the bimanual coordination mode (i.e., an individual completing a two-handed task) or the intermanual coordination mode (i.e., two people completing a two-handed task). When comparing these coordination modes, various research domains have reported an intermanual “mode effect” of speed. Research suggests that the difference in performance may depend on fundamental characteristics of each coordination mode that facilitate or impede speed during two-handed tasks. To further investigate this intermanual speed advantage, a task was constructed to exploit a hypothesized bimanual limitation that may underlie this mode effect: bimanual visuomotor coupling. Results replicated the intermanual speed advantage and showed a higher degree of visuomotor coupling during bimanual performance. Subsequent analyses suggest that speed during two-handed tasks may be a function of visuomotor coupling, regardless of coordination mode.

Bimanual Coupling and the Intermanual Speed Advantage

This study investigated previously observed differences in speed when completing a two-handed task either bimanually (i.e., the normal, two-handed mode) or intermanually (i.e., when such tasks are performed with different peoples’ hands). When comparing these two manual “coordination modes,” a phenomena referred to as the intermanual speed advantage has been observed. While various research domains have reported the intermanual speed advantage (i.e., a “mode effect”), recent research suggests that the observed difference in performance may depend on fundamental bimanual limitations that are not observed when using the intermanual coordination mode. To investigate the intermanual speed advantage, a task was constructed to exploit a hypothesized bimanual limitation that may underlie this mode effect: bimanual coupling. Results showed a replication of the intermanual speed advantage and higher between-hand coupling during bimanual performance. Subsequent analyses suggests that speed during two-handed tasks may be facilitated by decoupled movement of the limbs, regardless of coordination mode.

Is there a link between sensorimotor coordination and inter-manual coordination? Differential effects of auditory and/or visual rhythmic stimulations.

The purpose of this study was to test how the sensory modality of rhythmic stimuli affects the production of bimanual coordination patterns. To this aim, participants had to synchronize the taps of their two index fingers with auditory and visual stimuli presented separately (auditory or visual) or simultaneously (audio-visual). This kind of task requires two levels of coordination: (1) sensorimotor coordination, which can be measured by the mean asynchrony between the beat of the stimulus and the corresponding tap and by mean asynchrony stability, and (2) inter-manual coordination, which can be assessed by the accuracy and stability of the relative phase between the right-hand and left-hand taps. Previous studies show that sensorimotor coordination is better during the synchronization with auditory or audio-visual metronomes than with visual metronome, but it is not known whether inter-manual coordination is affected by stimulation modalities. To answer this question, 13 participants were required to tap their index fingers in synchrony with the beat of auditory and/or visual stimuli specifying three coordination patterns: two preferred inphase and antiphase patterns and a non-preferred intermediate pattern. A first main result demonstrated that inphase tapping had the best inter-manual stability, but the worst asynchrony stability. The second main finding revealed that for all patterns, audio-visual stimulation improved the stability of sensorimotor coordination but not of inter-manual coordination. The combination of visual and auditory modalities results in multisensory integration, which improves sensorimotor coordination but not inter-manual coordination. Both results suggest that there is dissociation between processes underlying sensorimotor synchronization (anticipation or reactivity) and processes underlying inter-manual coordination (motor control). This finding opens new perspectives to evaluate separately the possible sensorimotor and inter-manual coordination deficits present in movement disorders.

Effects of eye dominance (left vs. right) and cannabis use on intermanual coordination and negative symptoms in schizophrenia patients.

Based on the previous findings, it has been assumed that in schizophrenia patients, eye dominance and cannabis use will affect negative symptoms and intermanual coordination (IMC), an index of interhemispheric communication. But eye dominance, specifically the clinical findings for it, has been neglected in schizophrenia research. We therefore investigated its effects in 52 right-handed (36 right-eyed and 16 left-eyed) and 51 left-handed (35 left-eyed and 16 right-eyed) schizophrenia in-patients without and with drug use. Eye dominance affected IMC in all schizophrenia patients. When comparing right- and left-handers, we found that this result was only significant in the right-handed patients and in the smaller subgroup without drug use. In the right-handers, left eye dominance-like left-handedness-was associated with higher values in IMC and less pronounced manifestation of negative symptoms, right eye dominance was not. Thus, left-eyed right-handers may be more closely related to left-handers than to right-handers. In accordance with the results from the literature, we suggest that these findings are due to better interhemispheric connections and less impairment of white matter structures, especially in right-hemispheric regions. Moreover, cannabis use was related to higher scores in IMC and less pronounced negative symptoms, but only in the right-eyed and not in the left-eyed right-handers or in the left-handers. Hence, differences in eye dominance and handedness may be partially responsible for different results in interhemispheric connections among cannabis users. In conclusion, both eye dominance and use of cannabis should be taken into account when assessing clinical symptoms in schizophrenia patients.

Are Two Hands (From Different People) Better Than One? Mode Effects and Differential Transfer Between Manual Coordination Modes

We report an experiment in which we investigated differential transfer between unimanual (one-handed), bimanual (two-handed), and intermanual (different peoples' hands) coordination modes. People perform some manual tasks faster than others ("mode effects"). However, little is known about transfer between coordination modes. To investigate differential transfer, we draw hypotheses from two perspectives--information based and constraint based--of bimanual and interpersonal coordination and skill acquisition. Participants drove a teleoperated rover around a circular path in sets of two 2-min trials using two of the different coordination modes. Speed and variability of the rover's path were measured. Order of coordination modes was manipulated to examine differential transfer and mode effects. Differential transfer analyses revealed patterns of positive transfer from simpler (localized spatiotemporal constraints) to more complex (distributed spatiotemporal constraints) coordination modes paired with negative transfer in the opposite direction. Mode effects indicated that intermanual performance was significantly faster than unimanual performance, and bimanual performance was intermediate. Importantly, all of these effects disappeared with practice. The observed patterns of differential transfer between coordination modes may be better accounted for by a constraint-based explanation of differential transfer than by an information-based one. Mode effects may be attributable to anticipatory movements based on dyads' access to mutual visual information. Although people may be faster using more-complex coordination modes, when operators transition between modes, they may be more effective transitioning from simpler (e.g., bimanual) to more complex (e.g., intermanual) modes than vice versa. However, this difference may be critical only for novel or rarely practiced tasks.

Are Two Hands (from Different People) Better than One? Transfer between Unimanual, Bimanual, and Intermanual Coordination Modes

We report an experiment investigating transfer effects between unimanual (one-handed), bimanual (two-handed), and intermanual (different peoples’ hands) coordination modes. From an information-based perspective, coordination at the individual level should positively transfer to coordination at the interpersonal level, and vise versa. From a constraint-based perspective, simpler coordination tasks (e.g., at the individual level) should positively transfer to a more complex one (e.g., at the interpersonal level), but not vise versa. Participants drove a teleoperated rover using different manual coordination modes in a within-subjects design, and their speed was measured. The resulting pattern of transfer effects across coordination modes is better accounted for by a constraint-based explanation. However, those transfer effects disappear rapidly with practice. The current results lead us to conclude that team motor skills are not immediately transferable to individual motor skills.

Neural Activation and Functional Connectivity during Motor Imagery of Bimanual Everyday Actions

Bimanual actions impose intermanual coordination demands not present during unimanual actions. We investigated the functional neuroanatomical correlates of these coordination demands in motor imagery (MI) of everyday actions using functional magnetic resonance imaging (fMRI). For this, 17 participants imagined unimanual actions with the left and right hand as well as bimanual actions while undergoing fMRI. A univariate fMRI analysis showed no reliable cortical activations specific to bimanual MI, indicating that intermanual coordination demands in MI are not associated with increased neural processing. A functional connectivity analysis based on psychophysiological interactions (PPI), however, revealed marked increases in connectivity between parietal and premotor areas within and between hemispheres. We conclude that in MI of everyday actions intermanual coordination demands are primarily met by changes in connectivity between areas and only moderately, if at all, by changes in the amount of neural activity. These results are the first characterization of the neuroanatomical correlates of bimanual coordination demands in MI. Our findings support the assumed equivalence of overt and imagined actions and highlight the differences between uni- and bimanual actions. The findings extent our understanding of the motor system and may aid the development of clinical neurorehabilitation approaches based on mental practice.

Effects of handedness (left vs right) and cannabis abuse on intermanual coordination and negative symptoms in schizophrenic patients of the paranoid type

Intermanual coordination as an index of interhemispheric transfer and negative symptoms were investigated in 50 left- and 42 right-handed schizophrenic inpatients of the paranoid type, also including drug abusers. The primary objective was to show that there were higher values in intermanual coordination and fewer manifestations of negative symptoms in the left-handed compared to the right-handed patients. This assumption was based on previous studies. Most importantly, right- and left-handed patients showed a different behaviour in intermanual coordination, when the duration of illness was taken into consideration. Thus, long-term left-handed paranoid patients performed better in intermanual coordination and showed fewer manifestations of negative symptoms than did long-term right-handed patients. These results were true for the large group of all patients, and among them for the subgroup of patients without drug abuse. Consequently, higher scores in intermanual coordination in left-handed patients may be related to a better interhemispheric crosstalk resulting in less pronounced negative symptoms. Secondary objectives assessed by explorative data analysis included the effects of cannabis abuse. While cannabis abuse may be more prevalent in left-handed patients, its effects may be more pronounced in right-handed patients, scoring higher in intermanual coordination and lower in manifestations of negative symptoms.

Psychomotor performance in relation to acute oral administration of Δ9-tetrahydrocannabinol and standardized cannabis extract in healthy human subjects

Abnormalities in psychomotor performance are a consistent finding in schizophrenic patients as well as in chronic cannabis users. The high levels of central cannabinoid (CB(1)) receptors in the basal ganglia, the cerebral cortex and the cerebellum indicate their implication in the regulation of motor activity. Based on the close relationship between cannabis use, the endogenous cannabinoid system and motor disturbances found in schizophrenia, we expected that administration of cannabinoids may change pattern of psychomotor activity like in schizophrenic patients. This prospective, double-blind, placebo-controlled cross-over study investigated the acute effects of cannabinoids on psychomotor performance in 24 healthy right-handed volunteers (age 27.9 +/- 2.9 years, 12 male) by comparing Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and standardized cannabis extract containing Delta(9)-THC and cannabidiol. Psychomotor performance was assessed by using a finger tapping test series. Cannabis extract, but not Delta(9)-THC, revealed a significant reduction of right-hand tapping frequencies that was also found in schizophrenia. As to the pure Delta(9)-THC condition, left-hand tapping frequencies were correlated with the plasma concentrations of the Delta(9)-THC metabolite 11-OH-THC. These effects are thought to be related to cannabinoid actions on CB(1) receptors in the basal ganglia, the cerebral cortex and the cerebellum. Our data further demonstrate that acute CB(1) receptor activation under the cannabis extract condition may also affect intermanual coordination (IMC) as an index of interhemispheric transfer. AIR-Scale scores as a measure of subjective perception of intoxication were dose-dependently related to IMC which was shown by an inverted U-curve. This result may be due to functional changes involving GABAergic and glutamatergic neurotransmission within the corpus callosum.

Bimanual coordination as task-dependent linear control policies

When we perform actions with two hands in everyday life, coordination has to change very quickly depending on task goals. Here, we study these task-dependent changes using a bimanual reaching task in which participants move two separate cursors to two visual targets, or move a single cursor, displayed at the average position of the two hands, to a single target. During the movement, one of the hands is perturbed in a random direction using a viscous curl field. We have previously shown that feedback control, the structure of noise, and adaptation change between these two tasks as predicted by optimal control theory: feedback control is independent when the hands control two cursors, but becomes dependent when they move one cursor together. The same changes are observed even on trials in which no visual feedback about the cursor position is given. One assumption in this model is that coordinative motor commands can be described as a linear function of the state of the left and right hands. Here we test the assumption by studying the feedback corrections for 25 combinations of force fields applied to the two hands. Our study shows that feedback gains are constant across all levels of force fields strength, providing strong evidence that intermanual coordination for this task can accurately be explained by optimal task-dependent linear feedback gains.

Intermanual coordination: from behavioural principles to neural-network interactions.

Locomotion in vertebrates and invertebrates has a long history in research as the most prominent example of interlimb coordination. However, the evolution towards upright stance and gait has paved the way for a bewildering variety of functions in which the upper limbs interact with each other in a context-specific manner. The neural basis of these bimanual interactions has been investigated in recent years on different scales, ranging from the single-cell level to the analysis of neuronal assemblies. Although the prevailing viewpoint has been to assign bimanual coordination to a single brain locus, more recent evidence points to a distributed network that governs the processes of neural synchronization and desynchronization that underlie the rich variety of coordinated functions. The distributed nature of this network accounts for disruptions of interlimb coordination across various movement disorders.

Callosal Function in Multiple Sclerosis: Bimanual Motor Coordination

Evidence of callosal dysfunction in patients with multiple sclerosis (MS) was examined using a test of bimanual coordination. MS patients were slower than non-patients on the Bimanual Coordination Test (BCT) on both unimanual trials (simple motor speed) and bimanual trials (intermanual coordination). Further, when compared to normals, MS patients exhibited a substantially greater difference between bimanual and unimanual response time, suggesting a deficit in interhemispheric motor interactions. A subgroup of MS subjects who showed markedly inefficient callosal transmission had previously been identified on the basis of abnormal evoked potentials (low amplitude cross-callosal evoked potentials). In comparisons of MS subgroups, the deficit in bimanual motor coordination was found only in MS patients with EP evidence of inefficient callosal transmission. These data support the conclusion that deficits in bimanual motor coordination occur in MS and that these deficits are related to callosal dysfunction.

Intermanual Coordination in Relation to Handedness, Familial Sinistrality and Lateral Preferences

Intermanual coordination assessed by alternating finger tapping and finger-tapping asymmetry were investigated in 105 healthy right- and 105 left-handers and related to handedness, familial sinistrality and lateral preferences (in hand-clasping, arm-folding and eyedness). Compared to right-handers, left-handers with less pronounced left-hand preferences (Subgroup B) showed higher values in intermanual coordination and lower values in finger-tapping asymmetry. Moreover, familial sinistrality and eyedness interacted with handedness effects. While in right-handers intermanual coordination was significantly higher in subjects with dominant left eye, in left-handers of the Subgroup B it was somewhat higher in those with dominant right eye. Higher values in intermanual coordination and reduced asymmetry in finger tapping may be associated with a greater bihemispheric control and better performance in fast bimanual movements.

The functional anatomy of manual motor behavior after unilateral frontal lobe lesions

In normal brains different behavioral tasks lead to increased metabolism in different loci. Resting monkeys with acute hemineglect following periarcuate lesions show deficient glucose utilization (LCGU) in motor thalamus and other loci of the hemisphere with the lesion. To determine if the abnormal LCGU could be altered by a specific behavioral task, we used behavioral testing and training, and quantitative 2-deoxyglucose (2-DG) autoradiography. Animals reached criterion in a bimanual traction task (BMTT), then were tested for hand preference and responses to sensory stimuli, and received unilateral frontal or sham lesions. Operated animals showed hemineglect, and, on BMTT, intermanual coordination errors. 2-DG of frontals at rest showed deficient LCGU in 4 of 7 thalamic, and 1 of 4 cortical regions assessed. In contrast, only 2 thalamic and no cortical regions were deficient in pulling animals. Thus, in the face of structural damage and distant deficient neural activation, performance of a specific behavioral task may increase metabolism in specific brain loci, implying that plasticity of neural activation vis-a-vis behavioral demand is present even acutely after brain injury.

Coordination aspects of arm trajectory formation

Arm trajectory formation refers to that level of the motor control system where patterns of motor commands are generated from symbolic descriptions of arm movements. Therefore, such a level separates a domain of “motor planning” from a domain of “motor processing” and coordination refers to the synchronization of different motor processes, which may be nested at different levels, one inside the other. Trajectory formation defines one such level. More abstract levels of coordination concerned with the motion of the two hands (inter-manual coordination) and with the interplay between rotation and translation of one hand (intra-manual coordination) are experimentally investigated.

Some long-term motor effects of cerebral commissurotomy in man

The long-term effects of cerebral commissurotomy on motor co-ordination and dyspraxia were investigated in 8 patients who had undergone complete or partial commissurotomy 5–10 yr previously. Performance on a series of standardized motor co-ordination and manual dexterity tests was compared with the established norms. Although qualitative performance appeared essentially unimpaired on most tests the scores for speed were consistently below normal and also inferior to those reported for patients with various unilateral brain lesions. In certain bimanual tasks requiring rapid alternating motion and interdependent control severe qualitative and quantitative impairments were present. In addition, marked dysgraphia and mild ideomotor-type dyspraxia on the left side, and moderate dyscopia on the right were present up to 10 yr after surgery in patients with complete commissurotomy. It would appear from the results that interhemispheric communication becomes particularly important for motor output to the extent that the tasks involve complex intermanual coordination or hemispheric specialization with ipsilateral control. On a étudié les effets à long terme de la commissurotomie cérébrale sur la coordination motrice et la dyspraxie chez 8 malades ayant subi une commissurotomie compléte ou partielle, 6–10 ans auparavant. On a comparé leur performance à une série d'épreuves standardisées de coordination motrice et de dextérité manuelle avec les normes établies préalablement. Bien que la performance apparaisse au plan qualitatif essentiellement intacte à la plupart des tests, les scores de rapiditéétaient de façon cohérente au dessous de la normale et également inférieurs à ceux rapportés pour les malades atteints de lésions cérébrales unilatérales diverses. Dans certaines tâches bimanuelles exigeant un mouvement alternatif rapide et un contrôle interdépendent, on constatait des troubles graves à la fois sur les plans qualitatif et quantitatif. En outre, chez les malades avec commissurotomie compléte, on observait une dysgraphie nette et dyspraxie légère de type idéomoteur du côté gauche ainsi une dyscopie modérée à droite et ceci jusqu'à 10 ans aprés la chirurgie. De ces résultats, il ressort que la communication interhémisphérique devient particuliérement importante pour la sortie motrice si l'épreuve réclame une coordination intermanuelle complexe ou une spécialisation hémisphérique avec contrôle ipsilatéral. Bei 8 Patienten, die sich sechs bis zehn Jahre zuvor einer kompletten oder partiellen Kommissurotomie unterzogen hatten, wurden die Auswirkungen der cerebralen Kommissurotomie auf motorische Koordination und Dyspraxie untersucht. Die Leistungen bei einer Serie standardisierter Tests zur motorischen Koordination und Händigkeit wurde mit Normwerten verglichen. Obwohl die qualitative Leistung bei den meisten Tests im wesentlichen ungestört wirkte, waren die Leistungen in Bezug auf Geschwindigkeit übereinstimmend unter der Norm und auch unter den Ergebnissen, die von Patienten mit verschiedenen unilateralen Hirnläsionen erzielt werden. Bei gewissen bimanuellen Aufgaben, die rasche wechselnde Bewegung und gegenseitige Kontrolle verlangen, zeigten sich schwere qualitative und quantitative Beeinträchtigungen. Auβerdem waren ausgeprägte Dysgraphie und leichte ideokinetische Dyspraxie auf der linken Seite und mäβige Dyskopie auf der rechten Seite bis zu 10 Jahren nach der Operation bei den Patienten mit kompletter Kommissurotomie nachweisbar. Nach diesen Ergebnissen scheint die interhemisphärische Kommunikation besonders wichtig für den motorischen output zu sein, und zwar insbensondere bei den Aufgaben, die komplexe intermanuelle Koordination oder hemisphärische Spezialisierung mit ipsilateraler Kontrolle verlangen.