Left-hand Performance Research Articles

95 Handedness as a Consideration for Computerized Neuromotor Performance Testing

Objective:The COVID-19 pandemic created barriers to healthcare that necessitated changes in services to meet needs of individuals. With these changes, technological advances in computerized cognitive testing became critical. As researchers and clinicians accelerated adaptation of computerized testing formats, considerations for development and interpretation of such tools have proved imperative. One such computerized tool, RC21X, utilizes performance measurement software comprising 15 modules to evaluate an individual’s processing speed, memory, executive functions, and neuromotor coordination. Although initial data has revealed strong psychometric properties (Saganis et al., 2020), a need to explore various attributes of this web-based tool has emerged. The current study examined impact of dominant handedness on an RC21X neuromotor task.Participants and Methods:The sample consisted of 602 participants: 553 (91.86%) were right-hand dominant and 49 (8.14%) were left-hand dominant. Of participants who identified their sex, 81.2% were male, 18.3% were female; 0.5% chose not to identify. Age ranged from 7-95 years (M = 41.21, SD = 18.81). This study focused on the RC21X Eye-Hand Coordination subtest. Using a Fitts’ Law paradigm, the module provided instruction for participants to alternately press the “A” and “L” keys on a keyboard as quickly and accurately as possible using only one upper extremity (UE) at a time (tested separately for right then left UE). We computed a one-way between groups multivariate analysis of variance (MANOVA) to investigate handedness differences on task performance. Dependent variables were individuals’ performances on right- and left-UE tasks; the independent variable was dominant handedness. We conducted preliminary assumption testing with no serious violations noted. We also separated the sample by dominant handedness to compare right versus left-hand performance using paired samples t-tests within each group. There were no significant differences between the two groups on either age or sex.Results:There was a statistically significant difference between right-hand dominant and left-hand dominant participants on the dependent variables, F (2, 599) = 8.84, p < .001, Wilks’ Lambda = .971. Mean scores indicated that right-hand dominant participants (M = 52.87, SD = 20.42) outperformed their left-hand dominant counterparts (M = 46.30, SD = 12.79) when using their right UE, though both groups performed similarly when using their left UE (right-hand dominant M = 48.55, SD = 17.81; left-hand dominant M = 49.70, SD = 14.13). These findings were present despite expected results from paired samples t-tests that revealed individuals performed best with their dominant hand.Conclusions:Results revealed that handedness is necessary to consider in design and utilization of computerized neuropsychological tests. The large proportion of right-hand dominant individuals may have affected our results; however, our sample is representative of handedness distribution in the general population. Although our paired samples t-tests support validity of RC21X, continued investigation of computerized performance measurement tools is necessary. Future research must explore the possibility of an ordering effect (i.e., right-handed participants starting with their dominant UE, but left-handed participants starting with their nondominant UE) or due to construction of everyday items (e.g., computer keyboards) primarily for right-hand dominant people.

Reduced fine motor competence in children with ADHD is associated with atypical microstructural organization within the superior longitudinal fasciculus.

Recent work in healthy adults suggests that white matter organization within the superior longitudinal fasciculus (SLF) may, at least partly, explain individual differences in fine motor skills. The SLF is also often implicated in the neurobiology underlying attention deficit hyperactivity disorder (ADHD) as part of the attention network connecting frontal and parietal regions. While ADHD is primarily characterized by inattention, impulsivity and/or hyperactivity, atypical fine motor control is a common comorbid feature. This study aimed to investigate the association between reduced fine motor skills in ADHD and microstructural properties within the SLF. Participants were 55 right-handed children with ADHD and 61 controls aged 9-11years. Fine motor control was assessed using the Grooved Pegboard task. Children underwent high angular resolution diffusion MRI. Following pre-processing, constrained spherical deconvolution tractography was performed to delineate the three SLF branches bilaterally. Children with ADHD showed significantly poorer fine motor performance relative to controls in the non-dominant hand, indicated by significantly slower left handed Grooved Pegboard task performance. This slower response time for the non-dominant (left) hand was significantly associated with reduced apparent fibre density within the right SLF I, and reduced right SLF I, II and III volume. This finding was independent of spatial attention performance. These data support previous reports indicating that children with ADHD have poorer fine motor performance than controls in their non-dominant hand, and indicates that the neurobiological basis for impaired fine motor control may involve white matter properties within the contralateral SLF. This suggests that white matter properties in fronto-parietal areas may have broader implications than attention.

Neurophysiological Analysis of Intermanual Transfer in Motor Learning.

The purpose of this study was to examine the effect of motor training on motor imagery (MI), by comparing motor performance and motor cortex excitability changes with and without intermanual transfer of motor learning. Intermanual transfer was investigated in terms of excitability changes in the motor cortex and motor performance from right hand training to left hand performance. Participants were assigned to a transfer training group and a control group. We recorded motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS), applied to the left extensor carpi radialis (ECR) both with and without intermanual transfer. The results showed that after learning by the right hand, MEPs decreased during left hand MI. MEPs during MI were significantly decreased by unilateral training in the transfer training group. Since intermanual transfer plays an important role in stabilizing performance by the contralateral side, this result suggests that unilateral training decreases MEPs during MI on the contralateral side. In the control group, without right hand training, MEPs significantly increased after left hand training during MI. In the trained side, we found increased excitability in the agonist muscle area of the primary motor cortex. However, in the untrained side, excitability decreased in the homonymous muscle area of the primary motor cortex. This constitutes an increase in inhibitory effects and suggests that excitability changes in the respective neural circuit contribute to skilled performance by the ipsilateral and contralateral sides in the same motor task.

The effect of handedness on spatial and motor representation of pitch patterns in pianists.

This study investigated the effect of handedness on pianists’ abilities to adjust their keyboard performance skills to new spatial and motor mappings. Left- and right-handed pianists practiced simple melodies on a regular MIDI piano keyboard (practice) and were then asked to perform these with modified melodic contours (the same or reversed melodic contour causing a change of fingering) and on a reversed MIDI piano keyboard (test). The difference of performance duration between the practice and the test phase as well as the amount of errors played were used as test measures. Overall, a stronger effect for modified melodic contours than for the reversed keyboard was observed. Furthermore, we observed a trend of left-handed pianists to be quicker and more accurate in playing melodies when reversing their fingering with reversed contours in their left-hand performances. This suggests that handedness may influence pianists’ skill to adjust to new spatial and motor mappings.

A Novel Tunable Dual-band Left-Handed Metamaterial

In this paper, we propose a novel tunable left-handed metamaterial (LHM), the capacitor-loaded short wire pairs (CL-SWPs). It is composed of a pair of short wires connected through a variable capacitor. This LHM is single-sided, and it exhibits not only tunable negative permeability, but also a wide band negative permittivity. It is pointed out with theoretical analysis that its left-handed performance is related to the mutual coupling coefficient. A tunable dual-band LHM is also proposed by simply adding a double slits split ring resonator to this LHM. The simulated results indicate that the closer the two LH bands are, the better performance the CLSWP related left-handed band is, hence identifying our theoretical analysis. The proposed structure is geometrically simple, low-cost and easy for fabrication, and it can be used as a basic particle in the design of tunable multi-band LHMs.

The Effects of Hand Exercise Program on Activities of Daily Living of People Older Than 60 Years

Introduction: Aging is a dynamic and progressive process characterized by morphological, functional, and psychological changes, which restricts adaption to the environment and reduces the quality of life. Maintaining the ability of performing activities of daily living (ADL) is vital to the elderly and poor motor function is associated with higher dependency. Thus, this study aimed to evaluate the efficacy of hand resistance training and dexterity as a treatment package on the performance of ADL in the elderly. Material and Methods: A total of 20 senior adults were randomly (picking up by coded envelopes) assigned to intervention and control groups. We used Barthel test to evaluate the performance of ADL, and Box and Block test to evaluate the hand function. Results: According to results, changes in ADL were not statistically significant over time (P=0.583). However, the results of Box and Block test showed that right- and left-hand performance changes over time was statistically significant (P=0.002). Conclusion: Based on the results, 6 weeks training could improve hand function and dexterity and maintain the ability to perform ADL in the elderly.

Faking handedness: Individual differences in ability to fake handedness, social cognitions of the handedness of others, and a forensic application using Bayes’ theorem

ABSTRACT People usually describe their handedness honestly, but that need not necessarily be the case. A legal case is described of a murder said by the pathologist to be committed by a left-hander but the defendant claimed to be right-handed, and the first author assessed the defendant’s handedness as an expert witness. We know of no previous work on faking handedness, and so we tested 30 right-handers and 25 left-handers on various handedness tasks, and then asked the participants to repeat the tasks while faking being of opposite handedness. Social cognitions of handedness were assessed from participants’ knowledge of how other right- and left-handers would answer handedness questionnaires. Fake handedness was best differentiated using cursive lower-case sentence writing, upper-case written letters being less good at distinguishing, as also were simple motor tasks. Participants differed in social cognitions of handedness, and those with more accurate social cognitions were better able to fake. Personality measures did not predict faking ability. For forensic purposes a Bayesian analysis was carried out to evaluate the likelihood of right and left hand performance being true rather than faked, and the cursive lower-case writing provided strong posterior odds that, as claimed, the particular defendant was a true right-hander.

Development of FDEA Models to Measure the Performance Efficiencies of DMUs

Data envelopment analysis (DEA) is a linear programming-based methodology to measure the relative performance efficiencies of DMUs which produce multiple outputs by consuming multiple inputs. The input data and output data can be considered as a linguistic variables characterized by fuzzy numbers. So, in the present study, we extend DEA to fuzzy DEA (FDEA) in which the input and output data are taken as fuzzy numbers (FNs), in particular triangular FNs. In this paper, we develop two FDEA models to measure the left hand and right hand relative performance efficiencies of each DMU using $$\alpha$$ -cut approach. Further, we propose a ranking method to rank the DMUs based on left hand and right hand efficiencies. Finally, the developed FDEA models and proposed ranking models are illustrated with an example and then compared the results with geometric average efficiency index ranking method. The proposed model is also experimented with a real-life problem.

P254 The interaction of cross-limb transfer gains, intermittent theta-burst stimulation and subsequent learning in young and older adults

Introduction Recently we found evidence that following right hand motor training intermittent theta-burst stimulation (iTBS) applied to the ipsilateral primary motor cortex (M1) increased corticospinal excitability (CSE) and facilitated performance in the untrained hand (i.e., cross-limb transfer, CLT). Objectives Here we examine whether the interaction of CLT and iTBS can be exploited to drive improved learning in one hand following learning with the other hand, and to assess any age-related differences in this interaction. Materials and methods Eighteen young (Mage = 25.2 ± 5.7 years, 8 males) and seven healthy older adults (Mage = 66.4 ± 3.1 years, 6 males) practiced a ballistic motor task with their right index finger (150 trials, T1), after which iTBS was applied to the untrained M1. Another 150 training trials (T2) were then conducted. During T2, 13 participants (8 young, 7 older) practiced with their left hand (RL group) while 12 young participants continued practicing with their right hand (RR group). Performance (peak acceleration) and CSE were assessed before T1, pre- and post-iTBS, and following T2. Results Although iTBS facilitated untrained hand MEPs in both age groups (+29%, p = .005), untrained hand performance was facilitated by iTBS in young (+25%; p = .04), but not in older (−2%, p = .92), adults. Following T2, no differences in left hand performance gains (adjusted for post-iTBS performance) between RL and RR (12% vs. 9%, p=.88, Fig. 1A) were observed, although CSE gains in the left hand following T2 were greater following RL than RR (34% vs. −4%, p = .02, Fig. 1A). Conclusion In young but not older adults, iTBS-induced LTP-like plasticity can be utilised to drive performance gains in the untrained limb above and beyond those gains already induced by cross-limb transfer processes. With respect to left hand performance gains, no advantage was observed following left hand T2 training (‘training gains’) compared to right hand T2 training (‘CLT gains’). Thus, homeostatic plasticity effects following iTBS administered to the untrained M1 following right hand motor learning appear insufficient to drive greater subsequent training gains when training is then undertaken with the left hand relative to those gains which would continue to occur (during right hand training) as a result of cross-limb transfer. Download : Download high-res image (447KB) Download : Download full-size image

High-definition transcranial direct current stimulation to both primary motor cortices improves unimanual and bimanual dexterity

While most research on brain stimulation with transcranial direct current stimulation (tDCS) targets unimanual motor tasks, little is known about its effects on bimanual motor performance. This study aims to investigate the effects of tDCS on unimanual as well as bimanual motor dexterity. We examined the effects of bihemispheric anodal high-definition tDCS (HD-atDCS) on both primary motor cortices (M1) applied concurrent with unimanual and bimanual motor training. We then measured the effects with the Purdue Pegboard Test (PPT) and compared them to a sham stimulation. Between a pretest and posttest, 31 healthy, right-handed participants practiced the PPT on three consecutive days and received – simultaneous to motor practice – either HD-atDCS over the left and right M1 (STIM, n=16) or a sham stimulation (SHAM, n=15). Five to seven days after the posttest, a follow-up test was conducted. Two-way ANOVAs with repeated measures showed significantly increased performance for all PPT-scores (p<0.001) in both groups. The scores for the right hand, both hands, and overall showed significant TIME x GROUP interactions (p<.05) with more improved performance for the STIM group, while left hand performance was not significantly altered. These effects were most pronounced in the follow-up test. Thus, we can conclude that a bihemispheric HD-atDCS of both M1’s improves performance of unimanual and bimanual dexterity. The strength of the effects, however, depends on which hand is used in the unimanual task and the type of bimanual task performed.

Neural Network Underlying Intermanual Skill Transfer in Humans

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.

Priming Hand Motor Training with Repetitive Stimulation of the Fingertips; Performance Gain and Functional Imaging of Training Effects.

Application of repetitive electrical stimulation (rES) of the fingers has been shown to improve tactile perception and sensorimotor performance in healthy individuals. To increase motor performance by priming the effects of active motor training (arm ability training; AAT) using rES. We compared the performance gain for the training increase of the averaged AAT tasks of both hands in two groups of strongly right-handed healthy volunteers. Functional Magnetic Resonance Imaging (fMRI) before and after AAT was assessed using three tasks for each hand separately: finger sequence tapping, visually guided grip force modulation, and writing. Performance during fMRI was controlled for preciseness and frequency. A total of 30 participants underwent a two-week unilateral left hand AAT, 15 participants with 20 minutes of rES priming of all fingertips of the trained hand, and 15 participants without rES priming. rES-primed AAT improved the trained left-hand performance across all training tasks on average by 32.9%, non-primed AAT improved by 29.5%. This gain in AAT performance with rES priming was predominantly driven by an increased finger tapping velocity. Functional imaging showed comparable changes for both training groups over time. Across all participants, improved AAT performance was associated with a higher contralateral primary somatosensory cortex (S1) fMRI activation magnitude during the grip force modulation task. This study highlights the importance of S1 for hand motor training gain. In addition, it suggests the usage of rES of the fingertips for priming active hand motor training.

Display-control stereotype strength of left- and right-handers

Many aspects of the performance of left and right handed persons have been reported. It is generally found that (a) Performance of left-handers, when the workplace is set up according to their handedness, is as good as that of right-handers when using their preferred hand. (b) When using the non-preferred hand, left-handers performance is generally superior to that of right-handers, possibly due to their having had to adapt to a right-handed world. There has been little reported research on the difference of stereotype strength or expectancies of device operation for right- and left handers. This paper reports such research using a set of rotational and translational controls with displays in four different locations relative to the operator. It is found that there was no significant effect of handedness of the participant for horizontally-moving displays and left- and right-handers were equivalent in performance. For vertically-moving displays there were effects of handedness through interaction with controls and display location. Some conditions showed non-equivalence of left and right-handedness in stereotype strength. Relevance to industryAbout 10% of people are left-handed, yet live in a world that is largely designed for right-handers. Experiments are reported to show that, for many combinations of control and displays, there is no significant effect of handedness on stereotype strength.

Callosal apraxia: a 34-year follow-up study

ABSTRACTLoss of ability of the left upper limb (LUL) to correctly produce spatial and temporal components of skilled purposeful movements was reported 34 years ago in a woman with a callosal infarction. To learn about recovery, we recently reexamined this woman. This woman was tested for ideomotor apraxia by asking her to pantomime to command and to seeing pictures of tools. Whereas she performed normally with her right upper limb, her LUL remained severely apraxic, making many spatial (postural and movement) errors. Initially, she did not reveal loss of finger–hand deftness (limb-kinetic apraxia), and when tested again with the coin rotation task, her left hand performance was normal. Without vision, she could name objects placed in her left hand but not name numbers written in this hand. Since this woman had a callosal lesion, failure to recover cannot be accounted for by left hemisphere inhibition of her right hemisphere. Although failure for her LUL to improve may have been related to not using her LUL for skilled actions, her right hemisphere was able to observe transitive actions, and this failure of her LUL to produce skilled purposeful movements suggests her right hemisphere may have not had the capacity to learn these movement representations. Without vision, her ability to recognize objects with her left hand, but not numbers written on her left palm, suggests graphesthesia may require that her left hand did not have access to movement representations important for programming these numbers when writing.

Manual Ambidexterity Predicts Robotic Surgical Proficiency

The manual dexterity of a surgeon is known to be related with surgical proficiency. Recently, as an objective measurement of surgical skills, inanimate methods using several types of simulators have been introduced. Using these simulators, we aimed to investigate the impact of manual dexterity on laparoscopic and robotic surgical proficiency. Fellow surgeons, surgical residents, and medical students (n = 32) participated in this study. For the measurement of dexterity, the sums and differences of the right and left hand performance times for the Grooved Pegboard Test were used as an index of dexterity speed and ambidexterity, respectively. The performance times during three sessions of laparoscopic suturing using a D-box trainer and the performance scores during three sessions using two robotic suturing programs with different degrees of difficulty provided by the da Vinci® Skills Simulator™ (Intuitive Surgical Inc., Sunnyvale, CA) were analyzed according to the measured manual dexterity. Manual dexterity was not a significant factor for performance time during laparoscopic suturing, which was more influenced by participants' surgical experiences. In robotic suturing, the performance score was impacted significantly by manual dexterity in terms of ambidexterity rather than dexterity speed. For an easy robotic suturing task, the gap of proficiency between the lower and higher ambidexterity groups was decreased successively with each of the three sessions. However, that gap in cases with a difficult task was maintained consistently throughout all three sessions. The degree of ambidexterity was an initial predictor for proficiency with simulated robotic suture. However, this relation could be lessened through a few sessions of training, although for a more difficult task further repetitions would be needed.

Perceptual and motor laterality effects in pianists during music sight-reading

Forty-six right-handed pianists were tested in a music sight-reading task in which they had to perform on a keyboard. Stimuli were single notes or single triads (chords) presented tachistoscopically in the left or right visual field in form of musical notation or verbal labels. Left-hand, right-hand or two-hands performance was required. Results showed, besides the expected Simon effect producing faster responses for stimuli to be performed with the hand ipsilateral to the side of presentation, a complex pattern of laterality which depended primarily upon the requested motor output. A tendency in favor of the left hemisphere (right visual field, RVF) was observed, this asymmetry being significant only in the single-hand tasks. On the contrary, in the two-hands task an opposite asymmetry was observed with musical notation. Moreover, a strong unexpected role of the bass clef was observed, which penalized left hand performance in particular with LVF stimuli. This effect even overcame the Simon effect, suggesting the presence of a bias in favor of the left hemisphere in musical transposition. Results point to a variegated pattern of hemispheric asymmetries in music sight-reading which depend on both stimulus coding and motor output type (e.g. two- or single-hand performance). A RH asymmetry was observed during two-hands playing with musical notation. Conversely, playing with one hand seems more leftward lateralized. This pattern of asymmetry would reflect a LH ability in simple “core” music reading together with a RH ability in the coordination of simultaneous responses by the two hands.

The Influence of Parkinson's Disease Motor Symptom Asymmetry on Hand Performance: An Examination of the Grooved Pegboard Task.

This study examined the influence of motor symptom asymmetry in Parkinson's disease (PD) on Grooved Pegboard (GP) performance in right-handed participants. The Unified Parkinson's Disease Rating Scale was used to assess motor symptoms and separate participants with PD into two groups (right-arm affected, left-arm affected) for comparison with a group of healthy older adults. Participants completed the place and replace GP tasks two times with both hands. Laterality quotients were computed to quantify performance differences between the two hands. Comparisons among the three groups indicated that when the nonpreferred hand is affected by PD motor symptoms, superior preferred hand performance (as seen in healthy older adults) is further exaggerated in tasks that require precision (i.e., place task). Regardless of the task, when the preferred hand is affected, there is an evident shift to superior left-hand performance, which may inevitably manifest as a switch in hand preference. Results add to the discussion of the relationship between handedness and motor symptom asymmetry in PD.

Normative data for modified Box and Blocks test measuring upper-limb function via motion capture

Motion analysis is an important tool for examining upper-limb function. Based on previous work demonstrating a modified Box and Blocks (BB) test with motion capture to assess prosthetic performance, we collected data in 16 nondisabled participants to establish normative kinematics for this test. Four motions of the modified BB test were analyzed to establish kinematic data for upper-limb and trunk motion. The test was repeated for right and left arms in standing and seated positions. Data were compared using a nonparametric Friedman test. No differences were found between right- and left-hand performance other than for task completion time. Small but significant differences were found for standing and seated performance, with slightly greater ranges in standing for axial trunk rotation, medial-lateral sternum displacement, and anterior-posterior hand displacement. The kinematic trajectories, however, were very consistent. The consistency in our nondisabled data suggests that normative kinematic trajectories can be defined for this task. This motion capture procedure may add to the understanding of movement in upper-limb impairment and may be useful for measuring the effect of interventions to improve upper-limb function.

English

The principal objective of this work is to investigate the relationship between lateral functions of the brain and morphology of the hands, eyes and feet. The study was carried out with 233 volunteers within the age range of 18 to 27 years. Out of the total number of participants, 208 (94%) of them were right-handed and the remaining 13 (6%) were left-handed. The participants were divided into two groups and assessed by twenty items. First ten (Q1) and second ten (Q2) items were taken from Edinburg Handedness Inventory (EHI) and the Yetkin Laterality Questionnaire (YLQ). The degree of hand preference was determined by Geshwind scores (GSs). Q1 was used to assess only hand preference, while Q2 was used for laterality of the one side of the body from eye to foot. Statistically, non-significant (p&gt;0.05) difference (3%) was observed between the Q1 (63%) and Q2 (60%). Breadths and lengths of the hands were measured across 2 to 5 metacarpal region, from peripheral line on the wrist to middle fingertip. While the difference between the breadths of right and left hand was significant (p&lt;0.05), the difference between the lengths of hand was non-significant (p&gt; 0.05). The breadths and lengths of the feet were also measured in the same way. Subjects performed three different voluntary motor activities, such as basketing (throwing basketball: BT), aiming at (targeting: TT) and peg moving tasks (PMT) with their right and left hands in turn to perform the tasks, respectively. In the BT and TT tasks, the difference between the right and left hand performance was non-significant (p&gt;0.05), though, the difference was significant (p&lt;0.05) for PMT. The findings suggest that both the proximity of the hand preferences and the difference of the hand sizes could be the results of the hemispheric dominance in the brain. In this study, it was found that there was a significant difference for left- versus right- hand breadths and left and right-hand motor performances which is shown to be both morphological and functional in asymmetry. &nbsp; Key words:&nbsp;Laterality, hand preference, basketing, targeting, peg-moving, motor performances, brain asymmetry, human.

Aging, aerobic activity and interhemispheric communication.

Recent studies have shown that during unimanual motor tasks, aging adults show bilateral recruitment of primary motor cortex (M1), while younger adults show a suppression of the ipsilateral motor cortex. Additional work has indicated that increased bilateral M1 recruitment in older adults may be deleterious when performing some motor tasks. However, higher levels of physical fitness are associated with improved dexterity and fitness may mitigate the loss of both inhibitory and excitatory communication in aging adults. The goal of this study was to assess dexterity and interhemispheric motor communication in physically fit and sedentary middle-age (40–60 years) right handed participants using tests of hand deftness and transcranial magnetic stimulation (TMS). To behaviorally assess the influence of interhemispheric communication on motor performance, participants also perform the coin rotation deftness task while maintaining pinch force with the opposite hand (bimanual condition). We correlated these behavioral measures with the ipsilateral silent period using TMS to assess interhemispheric inhibition. Our results show that the middle-aged adults who were physically fit had better dexterity of their right hand (finger tapping and peg-board). When performing the coin rotation task the fit group had no between hand differences, but the sedentary group’s left hand performance was inferior to the their right hand. We found that better dexterity correlated with ipsilateral silent period duration (greater inhibition) thereby supporting the postulate that fitness improves interhemispheric motor communication.