Functional Corticospinal Projections from Human Supplementary Motor Area Revealed by Corticomuscular Coherence during Precise Grip Force Control

The purpose of the present study was to investigate whether corticospinal projections from human supplementary motor area (SMA) are functional during precise force control with the precision grip (thumb-index opposition). Since beta band corticomuscular coherence (CMC) is well-accepted to reflect efferent corticospinal transmission, we analyzed the beta band CMC obtained with simultaneous recording of electroencephalographic (EEG) and electromyographic (EMG) signals. Subjects performed a bimanual precise visuomotor force tracking task by applying isometric low grip forces with their right hand precision grip on a custom device with strain gauges. Concurrently, they held the device with their left hand precision grip, producing similar grip forces but without any precision constraints, to relieve the right hand. Some subjects also participated in a unimanual control condition in which they performed the task with only the right hand precision grip while the device was held by a mechanical grip. We analyzed whole scalp topographies of beta band CMC between 64 EEG channels and 4 EMG intrinsic hand muscles, 2 for each hand. To compare the different topographies, we performed non-parametric statistical tests based on spatio-spectral clustering. For the right hand, we obtained significant beta band CMC over the contralateral M1 region as well as over the SMA region during static force contraction periods. For the left hand, however, beta band CMC was only found over the contralateral M1. By comparing unimanual and bimanual conditions for right hand muscles, no significant difference was found on beta band CMC over M1 and SMA. We conclude that the beta band CMC found over SMA for right hand muscles results from the precision constraints and not from the bimanual aspect of the task. The result of the present study strongly suggests that the corticospinal projections from human SMA become functional when high precision force control is required.     

Precision Grip Control while Walking Down a Stair Step

The aim of this study was to determine whether the internal model regulating grip force (GF)/load force (LF) coordination during a brisk load increase is preserved when the lower extremities produce a perturbation during a single step-down task. We observed the coordination of the vertical ground reaction force (vGRF), GF and LF while holding a handheld object during a single step-down task. The 3 forces (vGRF, GF and LF) decreased during the start of the task. While the subject was descending, LF and GF became dissociated from vGRF and increased in value, probably to anticipate the first foot contact. Coordination of LF and GF was maintained until the maximal vGRF (knee extension). LF peaked in the same time window as vGRF, whereas GF peaked about 70 ms later. This desynchronization, which was previously observed in direct load increase on a handheld object, was interpreted to be a predictive action to ensure the smooth management of the brisk increase in load induced by the lower extremities. Incidentally, in this group, kinematic and dynamic differences were observed between men and women, which may highlight a gender-specific strategy to perform the step-down task. In conclusion, these results suggest that the internal model of precision grip is able to integrate a brisk load change, whatever its origin, and regulate the forces to provide an ideal GF to dampen a brisk load increase and secure the object.     

Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects

Few studies have investigated the control of grip force when manipulating an object with an extremely small mass using a precision grip, although some related information has been provided by studies conducted in an unusual microgravity environment. Grip-load force coordination was examined while healthy adults (N = 17) held a moveable instrumented apparatus with its mass changed between 6 g and 200 g in 14 steps, with its grip surface set as either sandpaper or rayon. Additional measurements of grip-force-dependent finger-surface contact area and finger skin indentation, as well as a test of weight discrimination, were also performed. For each surface condition, the static grip force was modulated in parallel with load force while holding the object of a mass above 30 g. For objects with mass smaller than 30 g, on the other hand, the parallel relationship was changed, resulting in a progressive increase in grip-to-load force (GF/LF) ratio. The rayon had a higher GF/LF force ratio across all mass levels. The proportion of safety margin in the static grip force and normalized moment-to-moment variability of the static grip force were also elevated towards the lower end of the object mass for both surfaces. These findings indicate that the strategy of grip force control for holding objects with an extremely small mass differs from that with a mass above 30 g. The data for the contact area, skin indentation, and weight discrimination suggest that a decreased level of cutaneous feedback signals from the finger pads could have played some role in a cost function in efficient grip force control with low-mass objects. The elevated grip force variability associated with signal-dependent and internal noises, and anticipated inertial force on the held object due to acceleration of the arm and hand, could also have contributed to the cost function.     

Effects of carpal tunnel syndrome on adaptation of multi-digit forces to object weight for whole-hand manipulation

The delicate tuning of digit forces to object properties can be disrupted by a number of neurological and musculoskeletal diseases. One such condition is Carpal Tunnel Syndrome (CTS), a compression neuropathy of the median nerve that causes sensory and motor deficits in a subset of digits in the hand. Whereas the effects of CTS on median nerve physiology are well understood, the extent to which it affects whole-hand manipulation remains to be addressed. CTS affects only the lateral three and a half digits, which raises the question of how the central nervous system integrates sensory feedback from affected and unaffected digits to plan and execute whole-hand object manipulation. We addressed this question by asking CTS patients and healthy controls to grasp, lift, and hold a grip device (445, 545, or 745 g) for several consecutive trials. We found that CTS patients were able to successfully adapt grip force to object weight. However, multi-digit force coordination in patients was characterized by lower discrimination of force modulation to lighter object weights, higher across-trial digit force variability, the consistent use of excessively large digit forces across consecutive trials, and a lower ability to minimize net moments on the object. Importantly, the mechanical requirement of attaining equilibrium of forces and torques caused CTS patients to exert excessive forces at both CTS-affected digits and digits with intact sensorimotor capabilities. These findings suggest that CTS-induced deficits in tactile sensitivity interfere with the formation of accurate sensorimotor memories of previous manipulations. Consequently, CTS patients use compensatory strategies to maximize grasp stability at the expense of exerting consistently larger multi-digit forces than controls. These behavioral deficits might be particularly detrimental for tasks that require fine regulation of fingertip forces for manipulating light or fragile objects.     

Intra-session and inter-day reliability of forearm surface EMG during varying hand grip forces

Surface electromyography (EMG) is widely used to evaluate forearm muscle function and predict hand grip forces; however, there is a lack of literature on its intra-session and inter-day reliability. The aim of this study was to determine reliability of surface EMG of finger and wrist flexor muscles across varying grip forces. Surface EMG was measured from six forearm flexor muscles of 23 healthy adults. Eleven of these subjects undertook inter-day test–retest. Six repetitions of five randomized isometric grip forces between 0% and 80% of maximum force (MVC) were recorded and normalized to MVC. Intra- and inter-day reliability were calculated through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM).Normalized EMG produced excellent intra-session ICC of 0.90 when repeated measurements were averaged. Intra-session SEM was low at low grip forces, however, corresponding normalized SEM was high (23–45%) due to the small magnitude of EMG signals. This may limit the ability to evaluate finer forearm muscle function and hand grip forces in daily tasks. Combining EMG of functionally related muscles improved intra-session SEM, improving within-subject reliability without taking multiple measurements. Removing and replacing electrodes inter-day produced poor ICC (ICC < 0.50) but did not substantially affect SEM.     

Cognitive-Motor Interference While Grasping,Lifting and Holding Objects

In daily life, object manipulation is usually performed concurrently to the execution of cognitive tasks. The aim of the present study was to determine which aspects of precision grip require cognitive resources using a motor-cognitive dual-task paradigm. Eighteen healthy participants took part in the experiment, which comprised two conditions. In the first condition, participants performed a motor task without any concomitant cognitive task. They were instructed to grip, lift and hold an apparatus incorporating strain gauges allowing a continuous measurement of the force perpendicular to each contact surface (grip force, GF) as well as the total tangential force applied on the object (load force, LF). In the second condition, participants performed the same motor task while concurrently performing a cognitive task consisting in a complex visual search combined with counting. In the dual-task condition, we found a significant increase in the duration of the preload phase (time between initial contact of the fingers with the apparatus and onset of the load force), as well as a significant increase of the grip force during the holding phase, indicating that the cognitive task interfered with the initial force scaling performed during the preload phase and the fine-tuning of grip force during the hold phase. These findings indicate that these aspects of precision grip require cognitive resources. In contrast, other aspects of the precision grip, such as the temporal coupling between grip and load forces, were not affected by the cognitive task, suggesting that they reflect more automatic processes. Taken together, our results suggest that assessing the dynamic and temporal parameters of precision grip in the context of a concurrent cognitive task may constitute a more ecological and better-suited tool to characterize motor dysfunction in patients.     

Prediction of handgrip forces using surface EMG of forearm muscles.

Evaluation of handgrip forces constitutes an essential component of ergonomic evaluation (e.g. of hand tools), but is difficult to perform at the workplace. The present study describes a series of experiments on 8 healthy male subjects to determine the validity of linear regression models using the surface electromyography (EMG) of up to 6 forearm muscles to predict handgrip forces. For isometric gripping tasks, normalized EMG to grip force calibrations using a series of dynamic force bursts up to 300 N resulted in a valid prediction of grip forces based on the EMG of 6 forearm muscles. Absolute differences between observed and predicted grip force were small (between 27 and 41 N) which shows that the proposed method might be used for the ergonomic evaluation of the use of hand tools. The EMG - handgrip force model appeared to be minimally affected by grip width, i.e. a model for 67 mm grip width was able to validly predict grip forces for 59 and 75 mm grip widths. Furthermore, it was shown that of the 6 forearm muscles studied at least 3 have to be assessed to arrive at a sufficient level of validity, while it seems to be irrelevant which 3 of those 6 forearm muscles are assessed.     

Intrinsic electric fields promote epithelization of wounds in the newt, Notophthalmus viridescens

The lateral electric fields (LFs) in the vicinity of small wounds made in hindlimb digit tip skin of Notophthalmus viridescens have been measured and manipulated. Healing of these wounds was assessed by crystal violet staining and by histology. Paired experiments were conducted on the animals: the healing of one digit's wound was compared with healing of the contralateral digit's wound whose LF was changed from that of its contralateral wound. When currents were passed through the animal (into one wound and out of the contralateral wound) so that the LF of one wound was zero while the contralateral wound had an enhanced LF, the wounds with the enhanced LF healed more rapidly than the wounds with the zero LF. When digits on one side were treated with 30 microM benzamil in an artificial pond water so that their wound LFs were reduced to approximately zero, and the contralateral wounds were kept in artificial pond water without benzamil so that they had normal wound LFs, there was significantly less epithelization of the benzamil-treated wounds than of the control wounds. This effect on wound healing was reversed by adding currents that restored the normal wound LFs, but not by adding currents that reversed the wound LFs to the opposite polarity. When currents were added to reverse the wound LFs on one side of the animal, leaving the contralateral wounds free of added currents, the wounds with the reversed LFs healed more poorly than the contralateral wounds with normal LFs. These results are consistent with the hypothesis that the intrinsic LFs in the vicinity of wounds promote epithelization of these wounds.     

Differential growth factor induction and modulation of human gastric epithelial regeneration

While several autocrine/paracrine growth factors (GFs) can all stimulate epithelial regeneration in experimentally wounded primary gastric cultures, clinical relevance for their non-redundant cooperative actions in human gastric ulcer healing is suggested by the sequential pattern of GF gene induction in vivo. Using new HGE cell lines able to form a coherent monolayer with tight junctions as well as using primary human gastric epithelial cultures, we show that EGF, TGFalpha, HGF and IGFs accelerate epithelial restitution upon wounding, independently of the TGFbeta pathway (as opposed to intestinal cells). However, they differently modulate cell behavior: TGFalpha exerts strong effects (even more than EGF) on cytoplasmic spreading and non-oriented protruding activity of bordering cells whereas HGF preferentially coordinates single lamella formation, cell elongation and migration into the wound. IGF-I and IGF-II rather induce the alignment of bordering cells and maintain a compact monolayer front. The number of mitotic cells maximally increases with EGF, followed by TGFalpha and IGF-I,-II. The current study demonstrates that GFs differentially regulate the regeneration of human gastric epithelial cells through specific modulation of cell shape adaptation, migration and proliferation, further stressing that a coordination of GF activities would be necessary for the normal progression of post-wounding epithelial repair.     

Hand preference in a captive island group of chimpanzees (Pan troglodytes)

Morphological cerebral asymmetries in chimpanzee brains, similar to those found in humans, in whom they are associated with speech and handedness, suggest the possibility of functional lateralization in the chimpanzee. This possibility was investigated by examining hand preferences in an island group of five chimpanzees on a series of unimanual and bimanual tasks that are diagnostic of human hand and cerebral dominance. Each subject was tested in a double compartment cage on three unimanual nonsequential, three unimanual sequential, and three bimanual coordination tasks. One of the three unimanual sequential tasks was a bar-press task that is analogous to the commonly used human finger-tapping task. For the unimanual tasks, exclusive of the bar-press, the chimpanzees showed a highly individualistic pattern of hand preference that did not change as a function of task complexity. On the bar-press task, four of five subjects produced higher rates with one hand compared to the other; however, relative hand performance on this task was unrelated to hand preference on the other unimanual tasks. For the group of subjects, performance rates did not differ between the left and right hands; however, a practice effect was observed for the right hand in all subjects. The bimanual tasks also revealed a complex pattern of individual handedness, with no trends apparent for the group as a whole. Consistent with previous findings, the results from these tests on this group of five chimpanzees suggest that cerebral morphological asymmetries in the chimpanzee are not associated with motor dominance as reflected in handedness.     

Possible mechanisms of action of growth factors and cell aging]

Main effects of growth factors (GFs) on proliferation seem to be mediated by second messengers (SMs). A variety of feed-backs in the SM system allows to suggest that cell cycling is determined by self-oscillations of levels of the SMs and SM-dependent proteins. GFs perform roles of parameter switches of the system functioning regimes; self-oscillations occur only if the GF levels are within certain range. This approach makes it possible to explain the GF synergy, dual roles of GFs as activators and inhibitors of proliferation, and cell cycle duration variability. It predicts that GFs must accelerate some cell cycle phases and decelerate other phase. When the GF levels are sharply changed, cells may become terminally differentiated, which allows to explain a limited number of cell divisions in culture. We can also explain why some oncogenes decrease the dependence of cells on GFs but cells undergo a limited number of divisions, and other oncogenes enable cells to divide unlimitedly.     

Multiple growth factor delivery for skin tissue engineering applications

Administration of exogenous growth factors (GFs) to a damaged site has been investigated for skin tissue regeneration. Among the many types of GFs and cytokines, epidermal growth factor, vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor, and hepatocyte growth factor could be specifically used for stimulating molecules in wound healing as well as for recovery of damaged skin tissues. It is speculated that delivered GFs could stimulate various cellular functions, including proliferation, migration, deposition of extracellular matrix molecules, and remodeling of collagen synthesis. Although the physiological wound healing process is complex, engineering strategies for proper delivery of multiple therapeutic GFs could enhance the quality and quantity of regenerated skin tissues. As compared to single delivery of a GF, recent studies have proven that any combination of multiple GFs and/or therapeutic chemical factors synergistically facilitates the regeneration of damaged skin tissues. In order to maximize the stability, bioactivity, intrinsic therapeutic functionality, and efficiency of internal delivery of cargo GFs, it is essential to utilize tissueengineered biomaterials and related composites as implantable platforms. Successful fabrication and development of skin tissue engineering applications as well as subsequent surgical implantation of these platforms might provide clinical treatment for superior skin regeneration. Therefore, the present review summarizes the biological functions, related signaling mechanisms, and recent developments of tissue engineering applications for multiple GF delivery.     

Learned Manipulation at Unconstrained Contacts Does Not Transfer across Hands

Recent studies about sensorimotor control of the human hand have focused on how dexterous manipulation is learned and generalized. Here we address this question by testing the extent to which learned manipulation can be transferred when the contralateral hand is used and/or object orientation is reversed. We asked subjects to use a precision grip to lift a grip device with an asymmetrical mass distribution while minimizing object roll during lifting by generating a compensatory torque. Subjects were allowed to grasp anywhere on the object’s vertical surfaces, and were therefore able to modulate both digit positions and forces. After every block of eight trials performed in one manipulation context (i.e., using the right hand and at a given object orientation), subjects had to lift the same object in the second context for one trial (transfer trial). Context changes were made by asking subjects to switch the hand used to lift the object and/or rotate the object 180° about a vertical axis. Therefore, three transfer conditions, hand switch (HS), object rotation (OR), and both hand switch and object rotation (HS+OR), were tested and compared with hand matched control groups who did not experience context changes. We found that subjects in all transfer conditions adapted digit positions across multiple transfer trials similar to the learning of control groups, regardless of different changes of contexts. Moreover, subjects in both HS and HS+OR group also adapted digit forces similar to the control group, suggesting independent learning of the left hand. In contrast, the OR group showed significant negative transfer of the compensatory torque due to an inability to adapt digit forces. Our results indicate that internal representations of dexterous manipulation tasks may be primarily built through the hand used for learning and cannot be transferred across hands.     

Antirotaviral potential of lactoferrin from different origin: effect of thermal and high pressure treatments

Rotaviral gastroenteritis causes a high rate of infant mortality and severe healthcare implications worldwide. Several studies have pointed out that human milk and dairy fractions, such as whey and buttermilk, possess antirotaviral activity. This activity has been mainly associated with glycoproteins, among them lactoferrin (LF). Thermal treatments are necessary to provide microbiological safety and extend the shelf life of milk products, though they may diminish their biological value. High hydrostatic pressure (HHP) treatment is a non-thermal method that causes lower degradation of food components than other treatments. Thus, the main objective of this study was to prove the antirotaviral activity of LFs from different origin and to evaluate the effect of several thermal and HHP treatments on that activity. LF exerted a high antirotaviral activity, regardless of its origin. Native LFs from bovine, ovine, swine and camel milk, and the human recombinant forms, at 1 mg/mL, showed neutralizing values in the range 87.5–98.6%, while human LF neutralized 58.2%. Iron saturation of bovine LF did not modify its antirotaviral activity. Results revealed interspecies differences in LFs heat susceptibility. Thus, pasteurization at 63 °C for 30 min led to a decrease of 60.1, 44.5, 87.1, 3.8 and 8% of neutralizing activity for human, bovine, swine, ovine and camel LFs, respectively. Pasteurization at 75 °C for 20 s was less harmful to the activity of LFs, with losses ranging from 0 to 13.8%. HHP treatment at 600 MPa for 15 min did not cause any significant decrease in the neutralizing activity of LFs.     

Brief communication: Hand preference for bimanual and unimanual feeding in captive gorillas: extension in a second colony of apes

Right-hand dominance is widely considered to be a uniquely human trait. Whether nonhuman primates exhibit similar population-level hand preferences remains a topic of considerable debate. Despite extensive research focusing on laterality in nonhuman primates, our interpretation of these studies is limited due to methodological issues including the lack of a common measure of hand preference and the use of tasks that may not be reliable indicators of handedness. The use of consistent methods between studies is necessary to enable comparisons within and between species and allow for more general conclusions to be drawn from these results. The present study replicates methods used in recent research reporting population-level right-handedness in captive gorillas (Meguerditchian et al.,2010). Observational data were collected on hand preference for unimanual and bimanual feeding in 14 captive western lowland gorillas (Gorilla gorilla gorilla). Individual-level preferences were found, primarily for bimanual feeding; however, the data reveal no group-level directional bias (contra Meguerditchian et al.). Like the study by Meguerditchian et al. (2010), though, bimanual feeding revealed significantly stronger hand preferences than unimanual reaching, and age, sex, group membership, or rearing history had no effect on hand preference. Finally, variations in diet and corresponding grip type between studies suggest that hand preferences may vary across bimanual tasks depending on grip morphology. This study aims to contribute to our existing knowledge of primate laterality by increasing the number of individuals investigated using methods that allow for comparisons with similar research.     

From Single Motor Unit Activity to Multiple Grip Forces: Mini-review of Multi-digit Grasping

This paper is a mini review of kinetic and kinematic evidenceon the control of the hand with emphasis on grasping. It isnot meant to be an exhaustive review, rather it summarizes currentresearch examining the mechanisms through which specific patternsof coordination are elicited and observed during reach to graspmovements and static grasping. These coordination patterns includethe spatial and temporal covariation of the rotation at multiplejoints during reach to grasp movements. A basic coordinationbetween grip forces produced by multiple digits also occursduring whole hand grasping such that normal forces tend to beproduced in a synchronous fashion across pairs of digits. Finally,we address current research that suggests that motor unit synchronyacross hand muscles and muscle compartments might be one ofthe neural mechanisms underlying the control of grasping.     

Comparative analysis of diadochokinetic movements.

Tests of diadochokinesia are an inherent part of a neurological examination. Various quantifying methods have been proposed to increase the objectivity, sensitivity, and reliability of such examinations. The methods used and analyses performed, however, differ substantially between tasks. We used a three-dimensional, ultrasound-based recording device to continuously record joint angles during three diadochokinetic movements, avoiding any external constraints of the movements. Alternate pronation and supination of the forearm, tapping with the whole hand and with the index finger in isolation were analyzed in a sample of 63 healthy control subjects. The most sensitive measure for capturing effects of gender, sex, and active hand was frequency. The right hand was faster than the left in all tasks, tapping performance declined with increasing age, and male subjects were faster than females in forearm diadochokinesia. Other measures that characterize speed of movement such as maximum angular velocities and accelerations did not yield comparable sensitivity in detecting the same statistical effects. However, angular velocity achieved the highest test-retest reliability for forearm diadochokinesia, while frequency was reproduced in the tapping tasks. Additional measures characterizing symmetry of the angular velocity profiles and intraindividual variability were shown to be largely independent of movement speed. Examples in neurological patients showed that the data define a valuable standard against which pathological performance can be precisely evaluated. In addition, the different measures captured dissociable aspects of motor performance that may further help to characterize the deficit and adjust therapy.     

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.     

Testing multiple coordination constraints with a novel bimanual visuomotor task

The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise), leftward (counterclockwise), inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3) between the left and right hand were introduced. As expected, isofrequency patterns (1∶1) were performed more successfully than multifrequency patterns (non 1∶1). In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3) than with the non-dominant left hand (3∶1, 2∶1, 3∶2). Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of augmented visual feedback.     

Grip pattern and finger coordination differences between pianists and non-pianists

The aim of this study was to assess differences of grip pattern and finger coordination in pianists and non-pianists, using hand tasks that were unrelated to pianistic practice. Eleven pianists with more than 10 years of intensive practice were compared to 14 non-pianists. Both groups performed four tasks with their right hand: (1) gross grip at fast velocity; (2) gross grip at slow velocity; (3) hook grip at fast velocity; and (4) hook grip at slow velocity. The three-dimensional coordinates were reconstructed using a kinematic analysis system, and the flexion and extension angles of the metacarpophalangeal joints were calculated. The phase diagrams were qualitatively and quantitatively appraised in order to identify differences between the groups. Principal component analysis was used to assess differences between pianists and non-pianists in terms of the reproducibility and regularity of palmar grip cycles. Coefficients of correlation between the joint angles were used to analyze finger coordination during the tasks. The pianists showed better reproducibility and regularity in the palmar grip pattern, as well as finger movements that were more coordinated when performing different hand tasks.