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PubMed1994

Hand-movement profiles in a tactual-tactual matching task: effects of spatial factors and laterality.

We examined the effect of spatial factors and hemispheric lateralization upon hand-scanning strategies in 14 right-handed men tested in a tactual-tactual matching task. The experiment involved comparisons (judgments of same or different) between two objects sequentially touched by the fingertips of the left or right hand. Stimuli were made of smoothly joined cubes whose junctions were not haptically discernible. Exploratory strategies were inferred from the durations and locations of hand contacts with any of the cubes composing the stimuli. Accuracy was greater when the same stimulus was touched twice by the same hand than when different hands were used to feel it. With regard to strategies, both hands touched the upper parts of the object longer than the lower parts. Subjects also inspected more portions of the objects ipsilateral to the hand used. Overall differences in time spent touching cubes were greater for the right hand than for the left hand, showing that touch times were less evenly distributed on object parts for the former than for the latter. In this study, the process of information gathering by touch appears to be determined by the intertwining integration of contextual factors (e.g., stimulus position in space), biomechanical constraints on hand movements, and such cognitive factors as hemispheric differences on the ability to encode spatial pattern information.

Adult↗
PubMedDate not supplied

Hand preference in simultaneous unimanual tasks: a preliminary examination.

The aim of the current investigation was to determine the pattern of hand use during simultaneous unimanual tasks. Two studies were conducted. The first experiment examined the pattern of hand use in a catching task, while performing a secondary writing task. Results showed that individuals had a decreased tendency to catch with their preferred hand when their preferred hand was occupied, in comparison to when the preferred hand was unoccupied. The second experiment examined the pattern of hand use during a support and reach task, where the use of both hands was required. Here, results indicated that participants preferred to support themselves with their nonpreferred hand and reach with preferred hand toward right hemispace. With respect to left hemispace, participants showed the reverse pattern. This pattern of hand use indicates an important role for the nonpreferred hand, which has been relatively unexplored by researchers.

Adult↗
PubMed1991

[Releasing phenomenon of well learned praxis with right hand].

We report a case with "releasing phenomenon of well learned praxis" with right hand caused by cerebral infarction in the territory of left anterior cerebral artery. A 71-year-old right-handed woman suddenly developed motor paralysis in right lower and upper limbs associated with mutism. Motor paralysis of the right upper limb and speech disturbance improved gradually. At this period it was noted that she grasped and used an object in front of her with right hand against her own will. The neurological findings about one month after the onset of the disease revealed very mild weakness of the right upper extremity and severe motor paralysis of the right lower limb. In addition, tendon reflex was exaggerated in the right lower limb and sensory disturbance was noted in the region distal from the right knee. Neuropsychologically, ideomotor apraxia was observed in the left hand. Pathological gasping of the right hand was also noted. When the patient saw and touched an object, she used it with her right hand against her own will, and her left hand voluntarily hindered the right hand. This behavior is apparently similar with the "compulsive manipulation of tools" reported previously. However, the following hitherto unknown phenomena were observed in the present patient: Her right hand performed pantomimic movement for the use of objects orally described by the examiner without visually presenting them. The right hand also tended to imitate the gestures of the examiner automatically, even if the patient was not asked for imitating the gestures. These behavioral abnormalities of the right hand was thought to be liberated from the inhibition system.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Connective tissues of the hand and foot.

In this paper we are submitting studies on the onto- and phylogenetic development of the superficial muscular and fascial layers of the hand and forearm of mammals. The object of this study was to investigate the following items: the ontogenetic development of the m. flexor digitorum superficialis, of the m. flexor digitorum profundus, of the m. palmaris longus, of the palmaris brevis of the human hand, the nerve supply of these muscles, the development of palmar and plantar aponeurosis and of other fasciae related to the palmar and plantar aponeuroses. We compared conclusions drawn from the studies on the ontogenetic development with observations gained from the phylogenetic development of the structures of the human hand and forearm and applied our findings to various species of mammals. The results of these comparisons are expressed in this study presenting interpretations of the phylogenetic development of superficial muscular and fascial layers of the mammalian hand and foot. Furthermore we ascertained the homology of the superficial muscular and fascial layer of the mammalian autopodion, we reviewed one of the theories on the origin of Dupuytren's contracture and commented on opinions of the developmental origin of certain muscular varieties present in the human hand and forearm. Apart from this we established certain basic data on the development of the fasciae of the human hand and foot. Our findings on the variability of the palmar aponeurotic attachments of the human hand were confronted with the incidence and frequency of one particular finger when affected by a Dupuytren's contracture and we commented on the predisposition of certain fingers or toes for the affliction of this impairment. We conducted 152 series of histological sections through the hand and feet of embryos and foetuses sized 12-100 mm in c.-r. length, as well as 84 series of histological transverse sections through human embryonal hands in order to study the ontogenetic development of superficial muscular and fascial layers of the human hand, forearm and foot. The embryonal extremities were cut transversally, parallel to the palm and several sagittal sections were carried out for control purposes. The phylogenetic development of the superficial muscular and fascial layers of the hand was investigated by specimens processed under a micro-dissecting microscope. 55 specimens of various extremities were thus prepared, obtained from 22 species of mammals. Many animals were selected in order to cover species of mammals significant for their evolution.(ABSTRACT TRUNCATED AT 400 WORDS)

Fascia↗
PubMedDate not supplied

Hand decontamination: nurses' opinions and practices.

Infection is spread in hospital mainly by hands, making hand decontamination the most important means of preventing dissemination. There is some evidence to suggest that when access to hand-decontaminating agents is poor or the agents available are disliked, hands are washed too seldom, increasing risks of cross-infection. However, little attention has been paid to the use of towels and factors which promote their use, although it is known that damp hands transfer bacteria more readily than dry ones and that hands which become sore through poor drying have higher bacterial counts, contributing to the risk of cross-infection. This paper reports the results of the Nursing Times Hand Drying survey designed to assess nurses' access to hand decontamination agents and towels. The results suggest that the 112 nurses who participated were aware of the need for attention to hand hygiene but that access to both hand-decontaminating agents and paper towels was variable. Forty-one per cent complained of a shortage of soap and although nearly all used paper towels, these were in many cases of poor quality. Such towels were perceived as damaging to hands, leaving them feeling damp and sore. Good-quality, soft, paper towels were much appreciated by respondents in this sample. It is concluded that the quality of paper towels contributes to good infection control practice.

Cross Infection↗
PubMed1997

Radiographic hand osteoarthritis: incidence, patterns, and influence of pre-existing disease in a population based sample.

OBJECTIVE: Osteoarthritis (OA) is the most common type of arthritis; involvement of joints in the hand is highly prevalent, especially in the elderly. Few data are available on the incidence of hand OA in men and women or on the association between OA in one hand joint with incidence in others. METHODS: We studied the cumulative incidence of radiographic hand OA in a population based group of men and women, and evaluated whether baseline OA in one joint affected OA rates in other joints in the hand. Study subjects were 751 members of the Framingham Study cohort, who had a baseline right hand radiograph taken in 1967-1969 (mean age 55+/-5.58) and followup radiographs 24 years later. RESULTS: In those without OA at baseline, women had more incident disease than men in almost all hand joints, but the joints most frequently affected were the same in both sexes: the distal interphalangeal (DIP), followed by the base of the thumb, proximal interphalangeal (PIP), and metacarpophalangeal (MCP) joints. The MCP joint group was the only one in which the incidence in men was comparable to incidence in women. Prevalent OA in one or more joints in a row (e.g., MCP) markedly increased the risk of incident OA in other joints in the same row. Also, prevalent OA in one joint in a finger (a ray) increased the risk of incident OA in other joints in that ray. Prevalent OA in either DIP or PIP joints at baseline substantially increased the risk of incident OA in all other hand joints. Thumb base OA at baseline increased risk in MCP joints, and to a lesser extent, DIP and PIP joints. CONCLUSION: Cumulative incidence was generally higher in women than men, baseline OA in one joint in a row markedly increased the risk of developing OA in other joints in the same row, and baseline OA in a joint in a ray similarly increased risk in that ray. Interphalangeal joint OA at baseline appeared to increase subsequent OA in all hand joints, baseline OA in the thumb was not as strong a predictor. This descriptive information on incidence of radiographic hand OA should generate new hypotheses about why OA affects hands in particular patterns.

Age Distribution↗
PubMed1998

Major review: ocular sighting dominance: a review and a study of athletic proficiency and eye-hand dominance in a collegiate baseball team.

PURPOSE REVIEW: Laterality preference in sensory and motor functions of symmetrically disposed organisms have been studied for centuries. The relation between handedness and the eyes and vision (ocular sighting dominance) has been a focal point despite their physiologic dissimilarity. STUDY: To examine a college varsity baseball team for handedness and ocular sighting dominance to determine if their patterns of eye-hand dominance differed from the normal population and/or contributed to their individual relative success compared to their peers. Specifically: whether crossed eye- hand dominance favors the batter and uncrossed eye-hand dominance favors the pitcher. SUBJECTS AND METHODS: Twenty five UF varsity players were examined. All were male. Their visual acuity, stereoscopic vision, ocular motility and ocular sighting dominance were determined, the last by a pointing test which allowed the diagnosis of a central form of ocular dominance, but was not per se affected by handedness. Handedness was determined by preferred arm for throwing or hitting. No subject was ambidextrous. A control population was established consisting of the first 100 consecutive adults seen by the first author in the UF Eye Center with 20/20 vision O.U. and a normal eye exam. RESULTS: The control group displayed eye-hand dominance patterns similar to those previously reported in the literature for the general population. In the experimental group of baseball players, the incidence of conventionally predominant (in normals) ipsilateral or uncrossed eye-hand dominance was much lower (39%) than the normal control population (65%). The incidence of contralateral or crossed eye- hand dominance was 35%, twice that of the normal control population (18%) (p<0.01). The incidence of central ocular dominance with right or left handedness was 26% or 50% higher than a normal control population (17%) (p<0.25). With regard to individual performance, those players with central ocular dominance, whether right or left handed, were the most successful players in both pitching and batting. Pitchers who were uncrossed eye-hand dominant were distinctly more successful than crossed. Batters who were crossed eye-hand dominant were slightly more successful than uncrossed. CONCLUSIONS: The pattern of eye-hand dominance appears related to athletic proficiency for baseball. Warning: Note well: This information may be useful in career guidance but does not justify or medically indicate attempts to alter ocular sighting dominance or eye-hand dominance patterns as these are determined probably genetically or at such an early age that they cannot be successfully altered later. Attempts to so alter them are historically fraught with irremediable psychological or physical injury to the subject, including permanent incapacitating double vision.

Adult↗
PubMed2006

Hand preference for writing and associations with selected demographic and behavioral variables in 255,100 subjects: the BBC internet study.

In an Internet study unrelated to handedness, 134,317 female and 120,783 male participants answered a graded question as to which hand they preferred for writing. This allowed determination of hand preference patterns across 7 ethnic groups. Sex differences in left-handedness were found in 4 ethnic groups, favoring males, while no significant sex differences were found in three of the groups. Prevalence of left-handedness in the largest of the ethnic groups (self-labelled as "White") was comparable to contemporary hand preference data for this group [Gilbert, A. N., & Wysocki, C. J. (1992). Hand preference and age in the United states. Neuropsychologia, 30, 601-608] but the prevalence of left-handedness in individuals >70 years of age was considerably higher in the present study. Individuals who indicated "either" hand for writing preference had significantly lower spatial performance (mental rotation task) and significantly higher prevalence of hyperactivity, dyslexia, asthma than individuals who had clear left or right hand preferences, in support of Crow et al. [Crow, T., Crow, L., Done, D., & Leask, S. (1998). Relative hand skill predicts academic ability: global deficits at the point of hemispheric indecision. Neuropsychologia, 36, 1275-1282]. Similarly, an association of writing hand preference and non-heterosexual orientation was clearest for individuals with "either" writing hand responses. We conclude that contradictions in the literature as to whether or not these variables are linked to handedness stem largely from different definitions of hand preference. Due to a lack of statistical power in most studies in the literature, the "either" hand writing preference group that yielded the most salient results in this study is not normally available for analysis.

Adolescent↗
PubMed2004

Cleft hands with six metacarpals.

PURPOSE: The purpose of this study was to identify children with cleft hands whose radiographs showed metacarpal polydactyly with 6 metacarpals to support the hypothesis that cleft hand develops not as a result of a longitudinal failure of formation but through a process of central polydactyly and osseous syndactyly. METHODS: We screened the hand radiographs of all children with a transverse or longitudinal deficiency of the upper limb and identified 8 children with cleft hands containing 6 metacarpals. RESULTS: Six cleft hands had a missing middle finger and consisted of a thumb and index finger separated from the ring and small fingers by a V-shaped central cleft. Two children had a more severe form of cleft hand with absence of both the index and middle fingers but presence of 6 metacarpals. CONCLUSIONS: These 8 cleft hands containing 6 metacarpals showed progression of polydactyly of the middle finger and osseous syndactyly between the 2 middle finger metacarpals and the adjacent index and ring finger metacarpals. This contradicts a longitudinal failure of formation mechanism and supports the alternative hypothesis that cleft hand, polydactyly, and syndactyly develop through a similar teratogenic mechanism. The 2 cleft hands that had more severe suppression of the index and middle fingers yet had 6 metacarpal polydactyly provided confirmatory evidence that both typical cleft hands and the more severe manifestations of cleft hand with absence of multiple digits develop through a similar failure of induction mechanism.

Child↗
PubMed2004

Factors influencing residents' decisions to pursue a career in hand surgery: a national survey.

PURPOSE: The number of programs offering hand surgery fellowships has remained approximately the same over a 6-year period while the number of fellows within these programs has decreased by 46%. This study aimed to identify factors that persuaded or dissuaded orthopedic and plastic surgery residents in choosing hand surgery as a career. METHODS: We conducted a national survey of final-year orthopedic (n = 600) and plastic surgery (n = 177) residents. We developed an internet questionnaire based on literature review and focus group discussions. A Web site link was sent via e-mail to program directors of accredited orthopedic and plastic surgery programs for distribution of this anonymous survey to the residents. Factor analysis combined items into an "intellectual issues" category and a "lifestyle issues" category. Logistic regression was used to evaluate factors that predict an outcome of entering a hand surgery fellowship. RESULTS: We achieved a 30% response rate. Respondents and nonrespondents were not significantly different in terms of gender and race. After controlling for age, gender, marital status, and specialty, residents who enjoyed the intellectual issues of the hand surgery field were more likely to pursue a hand surgery fellowship (odds ratio = 10.1; 95% confidence interval = 3.3-30.8). Although a positive attitude toward lifestyle issues of the hand surgery field tended to be associated with pursuit of a hand surgery fellowship, the relationship was much weaker (odds ratio = 2.5; 95% confidence interval = 0.8-7.3). CONCLUSIONS: Lifestyle issues associated with a career in hand surgery such as low reimbursement and long hours were not the most important factors to residents when considering a career in the field. Residents pursued hand surgery primarily because of factors such as interest in and exposure to this field. To prevent a potential shortfall of hand surgeons, both orthopedic and plastic surgery programs must strengthen residents' exposure to hand surgery education in their training.

Adult↗
PubMed2002

The acquisition of bimanual coordination is mediated by anisotropic coupling between the hands.

The present study was designed to test two predictions from the coupled oscillator model of multifrequency coordination. First, it was predicted that multifrequency tasks that match the inherent manual asymmetry (i.e., the preferred hand assigned to the faster tempo) would be easier to learn than tasks that do not match the inherent dynamics (i.e., the non-preferred hand assigned to the faster tempo). Second, in the latter case acquisition of the multifrequency coordination would involve a reorganisation of the coupling dynamics such that the faster hand would exert a greater influence on the slower hand than vice versa. Sixteen right-handed volunteers received extensive training on a 2:1 coordination pattern involving a bimanual forearm pronation-supination task. Participants were randomly assigned to one of two groups: 1L:2R in which the preferred right hand performed the higher frequency, or 2L:1R in which the non-preferred left hand performed the higher frequency. The dynamic stability of the patterns was assessed by the ability of participants to maintain the coordination pattern as movement frequency was increased. Changes in the directional coupling between the hands was assessed by transition pathways and lead-lag relationship evident in a 1:1 anti-phase frequency-scaled coordination task performed prior to and following three practice sessions of the 2:1 task. The predicted differential stability between the multifrequency patterns was evident in the initial acquisition sessions but by the end of training the two patterns evidenced equivalent stability. Unexpectedly, for both groups the fast hand displayed greater variability in amplitude and movement frequency than the slow hand perhaps reflecting anchoring afforded to the slow hand by synchronising movement endpoints with the auditory pacing metronome. Analysis of pre- to post-training changes to the coupling dynamics in the 1:1 anti-phase task support the hypothesis that acquisition of the 2L:1R pattern involved reorganisation of the inherent dynamics.

Adult↗
PubMed2005

Hand preference in Turkish population.

The distribution of hand preference (self report) was studied in siblings and their parents originating from all parts of Turkey (N = 22,461). In total sample and siblings, there were significantly more right-handed women than men, and significantly more left-handed men than women--no significant sex difference for parents' handedness. The relative number for the right-handed parents significantly exceeded that for the right-handed siblings; the relative number for the left-handed siblings significantly exceeded that for the left-handed parents. It was concluded that there may be a sex difference in hand preference, but being only about 1% more left-handed men, and only about 1% more right-handed women; the right-handedness in new generation (siblings) is less than that in old generation (parents), due to freeing from cultural pressures against the left-hand use in everyday activities.

Adolescent↗
PubMed1996

Observations on hand movements in Rett syndrome: a pilot study.

UNLABELLED: It has been assumed that the stereotyped hand movements in Rett syndrome are symmetrical, midline and that they prevent purposeful use of the hands. Their relationship with respiration has not been previously explored. MATERIAL AND METHODS: Twenty-five girls whose Rett syndrome included disorganised breathing were selected. Their parents were contacted and interviewed by telephone at their convenience. None refused. RESULTS: The hand movements were asymmetrical in 44% of girls. Those with mainly unilateral hand movements used the same hand for purposeful tasks. The hand movements appeared to change with changing emotional or mental states. In 72% of girls the intensity of hand movements varied directly or inversely with the respiratory pattern. CONCLUSION: In almost half of the Rett girls the hand stereotypy is asymmetrical and non-midline. It is not the hand movements which prevent purposeful use of the hands. The hand movements together with the erratic breathing are employed as a useful means of communication.

Arousal↗
PubMed1996

The measurement of hand preference: a validation study comparing three groups of right-handers.

Three groups of right-handers were identified using the Edinburgh Handedness Inventory. Exclusive strong right-handers (Rs: N = 18) reported that they always used the right hand for eight or more of the 10 activities, and usually used the right hand for the remainder. Exclusive weak right-handers (Rw: N = 15) usually used the right hand for three or more activities, and always used the right hand for the remainder. Predominant right-handers (Rp: N = 18) preferred the right hand for most items, but used the left hand for at least one activity. These groups did not differ on three measures of relative skill of the two hands: peg-moving, tapping and dotting. Groups Rs and Rw were also indistinguishable in terms of the hand used for reaching for cards placed in different spatial positions. However, the reaching measure did discriminate group Rp, which included some individuals who reached predominantly with the left hand. It is concluded that preference batteries should quantify degree of hand preference in terms of the number of activities for which a preference is shown, ignoring the distinction between 'usually' and 'always'. The behavioural reaching measure shows promise as a method for providing a unitary scale of hand preference.

Adult↗
PubMed1989

Cerebral somatosensory potentials evoked by posterior tibial nerve stimulation: lateralization and relation to handedness in left-handed normal subjects.

Somatosensory potentials evoked by stimulation of the right and left posterior tibial nerves were studied in left-handed normal subjects. Hand preference was assessed by the Edinburgh Handedness Inventory; a laterality score (Geschwind score) was calculated for each subject. Hand skill was assessed by the peg moving task. The mean amplitude of the N1 wave from the right cerebral cortex was found to be significantly larger than that from the left cerebral cortex. In the subjects without familial sinistrality, there was no statistically significant difference between the evoked potentials from the right and left sides. In the subjects with familial sinistrality, the mean amplitude of the N1 wave from the right cerebral cortex was found to be significantly larger than that from the left cerebral cortex. There was an inverse relationship between the lateralization quotient (LQ) for the N1 wave and left-hand preference. The amplitudes of the P1, N1, and P2 waves from the right cerebral cortex were positively linearly correlated with left-hand preference. There was an inverse relationship between LQ for the P1 and N1 waves and the right-hand skill. The left-hand skill was not correlated with LQ for the evoked potential. The LQs for the P1 and N1 waves were negatively linearly correlated with the difference between the right and left hand skills (right minus left peg moving times). The amplitudes of the P1 and N1 waves from the left cerebral cortex were found to be inversely related to the right hand skill. There was no relationship between the evoked potential amplitudes from the right cerebral cortex and left hand skill in the total sample. It was concluded that the stronger sensory feedback for the somatomotor foot area within the right cerebral cortex would contribute to left-footedness in left-handers; the asymmetric organization of the somatosensory potentials evoked by stimulation of the right and left PTNs correlates with hand preference and skill, but in an unexpected manner.

Adult↗
PubMed1998

[Compulsive manipulation of tools in the left hand following damage to the right medial frontal lobe].

In 1982, Mori and Yamadori first reported a woman who showed compulsive manipulation of tools (CMT) following an infarction in the left medial frontal lobe. When an object was shown, the patient's right hand reached, grasped and manipulated it properly against her will. Since then, there have been many similar case reports and CMT has been generally believed to occur in the right hand after damage to the left medial frontal lobe. However, there also have been a few case reports of CMT in the left hand of a patient with damage to the right medial frontal lobe. To clarify whether such a patient with CMT in the left hand is an exceptional case or not, we prospectively investigated CMT in the left hand of 10 patients with an infarction in the right medial hemisphere. All patients were examined within 6 weeks after stroke. Magnetic resonance images were used to determine the location and extension of a lesion. We found that 7 cases with a lesion involving the anterior cingulate gyrus (ACG) and the supplementary motor area (SMA) exhibited a grasp reflex and a visual grouping mainly in the left hand. Five of these 7 cases had a lesion extending into the middle and anterior parts of the ACG and displayed CMT in the left hand. Among those 5 patients, 2 with a lesion which was extensive enough into the ACG to involve almost entirely the anterior part of it adjoining the genu and anterior body of the corpus callosum showed a prominent CMT in the left hand. Two patients with a lesion principally confined to the SMA showed the grasp reflex and some subvarieties of the instinctive grasp reaction mainly in the left hand, but never showed visual grouping nor CMT. One patient with a lesion involving the posterior cingulate gyrus and medial parietal lobe but sparing both the SMA and ACG showed neither grasping responses nor CMT. From these observations, we conclude the following: (1) it is not an exceptional case that a right-handed patient with a right medial frontal lesion shows CMT in the left hand: and (2) extensive damage to the ACG involving its anterior part adjoining the genu and anterior body of the corpus callosum is most crucial for the development of CMT.

Adult↗
PubMed2003

The role of vision on hand preshaping during reach to grasp.

During reaching to grasp objects with different shapes hand posture is molded gradually to the object's contours. The present study examined the extent to which the temporal evolution of hand posture depends on continuous visual feedback. We asked subjects to reach and grasp objects with different shapes under five vision conditions (VCs). Subjects wore liquid crystal spectacles that occluded vision at four different latencies from onset of the reach. As a control, full-vision trials (VC5) were interspersed among the blocked vision trials. Object shapes and all VCs were presented to the subjects in random order. Hand posture was measured by 15 sensors embedded in a glove. Linear regression analysis, discriminant analysis, and information theory were used to assess the effect of removing vision on the temporal evolution of hand shape. We found that reach duration increased when vision was occluded early in the reach. This was caused primarily by a slower approach of the hand toward the object near the end of the reach. However, vision condition did not have a significant effect on the covariation patterns of joint rotations, indicating that the gradual evolution of hand posture occurs in a similar fashion regardless of vision. Discriminant analysis further supported this interpretation, as the extent to which hand posture resembled object shape and the rate at which hand posture discrimination occurred throughout the movement were similar across vision conditions. These results extend previous observations on memory-guided reaches by showing that continuous visual feedback of the hand and/or object is not necessary to allow the hand to gradually conform to object contours.

Adult↗
PubMed2005

Grasping with the left and right hand: a kinematic study.

The goal of the present study was to compare prehension movements of the dominant and the non-dominant hand. Twenty right-handed volunteers (age 20-30 years) reached forward to grasp a cylindrical object, which was lifted and then placed into a target position in a retraction-insertion movement. The movements were performed at three different velocities (normal, deliberately fast, or slowly) both, under visual control, and in a no-vision condition. Analysis of the kinematic data revealed that the speed of hand transport influenced pre-shaping of both hands in a similar way. In the visual condition, the grip aperture increased about linearly with peak transport velocity, while it increased non-linearly with shorter movement duration. Comparison of the regression parameters showed that these relationships were nearly identical for both hands. The dominant hand was faster in inserting the object into the target position. Otherwise, no significant inter-manual differences were found. During prehension without visual control, the fingers opened more and movement duration was prolonged. Except for a larger grip aperture of the dominant hand at the end of the acceleration phase, the kinematic data of both hands were again comparable. This invariance was in contrast to performance in fine motor skills such as a pegboard test and drawing movements, where there was a clear advantage of the dominant hand. The similar pre-shaping of both hands during prehension is discussed with regard to a common motor representation of grasping.

Adult↗