Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DEXTERITY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed2005

Age-related changes in grasping force modulation.

The aim of this study was to determine the effect of age on the modulation of forces produced by the digits and to determine the effects of practice on the control of these forces in young and older adults. Young (n = 14, 19-28 years) and old (n = 12, 67-75 years) adults used a precision grip to perform a variable force-tracking task (sine wave, 5-25% of maximum voluntary force) with their dominant hand. Participants performed 100 practice trials over 2 consecutive days. Results indicated that both groups improved accuracy of force tracking as a result of practice. Younger adults performed the task at a higher level in pre- and post-test conditions compared with older adults. Younger adults showed improvements in force control in force generation and release phases. Older adults reached performance levels comparable with younger adults' pre-test performance, but only after extended practice. In contrast to young adults, older adults' performance during the force release phases remained quite variable. These data suggest that older adults are impaired in the accurate release of grip force. Varied force release patterns that disrupt the precision of force modulation may contribute to older adults' diminished dexterous abilities.

Adult↗
PubMed2006

Asymmetries of long-latency intracortical inhibition in motor cortex and handedness.

Paired-pulse transcranial magnetic stimulation was used in three experiments to measure the properties of long-latency intracortical inhibition (LICI) acting on the relaxed first dorsal interosseus muscle of the left and right hand in right-handed volunteers. The experiments show that LICI is asymmetrical: it emerges more rapidly and is greater in the dominant than non-dominant hand shortly after activation of the LICI circuits, and is greater with low-intensity conditioning stimulus intensities in the dominant than non-dominant hand. These findings suggest that asymmetrical function of long-latency inhibitory circuits in motor cortex might contribute to the asymmetrical dexterity between the hands, possibly through their inhibitory control of the circuits responsible for short-latency inhibition.

Adolescent↗
PubMed2006

Neuromuscular-skeletal constraints on the acquisition of skill in a discrete torque production task.

The organisation of the human neuromuscular-skeletal system allows an extremely wide variety of actions to be performed, often with great dexterity. Adaptations associated with skill acquisition occur at all levels of the neuromuscular-skeletal system although all neural adaptations are inevitably constrained by the organisation of the actuating apparatus (muscles and bones). We quantified the extent to which skill acquisition in an isometric task set is influenced by the mechanical properties of the muscles used to produce the required actions. Initial performance was greatly dependent upon the specific combination of torques required in each variant of the experimental task. Five consecutive days of practice improved the performance to a similar degree across eight actions despite differences in the torques required about the elbow and forearm. The proportional improvement in performance was also similar when the actions were performed at either 20 or 40% of participants' maximum voluntary torque capacity. The skill acquired during practice was successfully extrapolated to variants of the task requiring more torque than that required during practice. We conclude that while the extent to which skill can be acquired in isometric actions is independent of the specific combination of joint torques required for target acquisition, the nature of the kinetic adaptations leading to the performance improvement in isometric actions is influenced by the neural and mechanical properties of the actuating muscles.

Adaptation, Physiological↗
PubMed2006

Representation of dynamic events triggered by motion lines and static human postures.

Artists and cartoonists are able to dexterously depict a running person on paper with the aid of 'motion lines'. We scientifically examined whether the cognitive system can exploit motion lines in constructing memory representations of the location of a running person depicted in a still image. A target depicting a standing or a running person with or without motion lines was presented to participants for 500 ms. Observers were required to reproduce the location of the target 1 s after its disappearance. Data from depicted leftward and rightward moving persons were collapsed. Memory displacement of the target was shown to be largest in the presence of motion lines and a posture indicating an identical direction of movement. By assessing the absolute localization error, we showed that there was no localization advantage toward a target with a symmetrical (standing) posture over one with an asymmetrical (running) posture. Our findings indicate synergetic interaction between the mechanisms responsible for processing of motion lines and human postures in the representation of dynamic events.

Analysis of Variance↗
PubMed1998

Tactile impairments cannot explain the effect of age on a grasp and lift task.

This experiment addressed the often-posed theory that age-related declines in manual dexterity result from diminished tactile function. We measured the time 'young' subjects (n=33; mean=45 years) and 'old' subjects (n=33; mean=74 years) needed to grip (thumb and index finger), lift, and transport a small metal sphere when vision was permitted and when blindfolded. Subjects began each trial by reaching for the sphere and were instructed to complete the entire task quickly. In the absence of visual information, placement of the finger and thumb for a secure grip and lift cannot be performed efficiently without tactile information. If age-related tactile changes are functionally significant for this task, then without visual information the 'old' group should show a disproportionate increase in the duration of the grip and lift phase of the task compared to the 'young' group. Perceptual thresholds for tactile pressure stimuli (Semmes-Weinstein filaments) confirmed well-known age-related changes. Age and vision effects were manifest mainly during the grip-lift phase (time from object contact to lift-off from its support surface), with the expected finding that the 'old' group required more time than 'young' group, regardless of visual condition. The main finding was that the 'grip-lift' duration in the 'no-vision' condition was about twice the duration observed in the 'vision' condition for both age groups (ratios of 2.1 and 2.3 for 'young' and 'old', respectively). This similar relative slowing for the two groups fails to support the hypothesis that old adults' ability to grip and lift the object was limited by changes in the availability or use of tactile information.

Adult↗
PubMed1999

Spinal cord implantation of avulsed ventral roots in primates; correlation between restored motor function and morphology.

Functional restitution following spinal cord implantation of avulsed ventral roots was assessed electromyographically and correlated with the morphology of the regenerated neural structures in primates. The C5-C8 ventral roots were avulsed from the spinal cord in seven Macaca fascicularis monkeys. In three animals the roots were immediately reimplanted into the ventrolateral part of the spinal cord. In two monkeys the avulsed roots were reimplanted with a delay of 2 months and in two control animals the roots were not reimplanted. There was substantial recovery of function after both immediate and delayed spinal cord implantation of the avulsed ventral roots. The population of neurons that had regenerated was larger than on the control side, indicating a rescue of cells after an immediate root implantation. Different functional types of neurons had been attracted to regrow axons to the implanted root as judged by their position in the ventral horn. Thus, neurons normally supplying antagonistic muscles, such as the triceps muscle, participated in the innervation of the biceps muscle. Functionally this deficient directional specificity was correlated to both spasticity and co-contractions among agonistic and antagonistic muscles. Occasional electromyographic signs of function occurred also in control animals where the avulsed roots had not been implanted. This recovery was found to depend on regrowth from the site of avulsion, within the pia mater among the leptomeningeal cells and to the avulsed roots. The acceptable functional dexterity regained due to corrective surgery is discussed in terms of neurotrophism and plasticity.

Animals↗
PubMed1999

Prehension movements and motor development in children.

The maturation of manual dexterity and other sensorimotor functions was assessed with various behavioural tests. In healthy children (age 4-5 years) and in adults, the kinematics of reaching and grasping, a bimanual task and fast repetitive tapping movements were analysed. Furthermore a comprehensive motor function score (MOT), probing agility and balance, was evaluated. In the prehension task, the straightness of the reaching trajectories increased with age. Children opened their grip relatively wider than adults, thus grasping with a higher safety margin. The speed of both tapping and bimanual movements increased with age, and higher scores were reached in the MOT. Although the different behavioural tests sensitively indicated maturational changes, their results were generally not correlated, i.e. the outcome of a particular test could not predict the results of other tasks. Hence there is no simple and uniform relationship between different behavioural data describing maturation of sensorimotor functions.

Adult↗
PubMed2001

Asymmetry of motor cortex excitability during a simple motor task: relationships with handedness and manual performance.

Transcranial magnetic stimulation (TMS) was used to assess the relative contribution of the corticospinal (CS) pathway in activating the first dorsal interosseous (FDI) muscle in each hand of 16 right- (RH) and 16 left-handed (LH) subjects with varied degrees of hand preference. It was hypothesised that asymmetry in corticospinal activation of the two hands may be related to hand preference and interlimb differences in manual performance. Subjects performed isometric index finger abduction at force levels of 0.5 N, 1 N and 2 N while TMS was applied at resting threshold intensity (T), 0.9T, or 0.8T. The amount of contraction-induced facilitation of the muscle evoked potential (MEP) was used as an estimate of corticospinal involvement in the task. Patterns of MEP facilitation in each hand were compared with measures of manual performance (finger tapping speed, Purdue pegboard, maximal FDI strength). Threshold TMS intensities for an MEP in FDI at rest were similar in LH and RH subjects, and did not vary between hands. Facilitation of the MEP with voluntary activation was larger overall on the left side (P<0.05), but the asymmetry was dependent on the degree of lateralisation of hand preference. For subjects with consistent hand preference (either LH or RH), MEP facilitation in active FDI was larger for the left hand. For non-consistent RH subjects, contraction-induced MEP facilitation was larger in the right FDI muscle than the left. Asymmetry of MEP facilitation was not correlated with differences between hands in finger tapping speed or performance in the pegboard task, but was associated with relative differences in FDI strength. MEP facilitation tended to be larger in the stronger FDI muscle of the pair. We conclude that corticospinal involvement in the command for index finger abduction is generally greater when the left hand is used, although in RH subjects the asymmetry is influenced by the degree of lateralisation of hand preference. The corticospinal asymmetry is not related to speed or dexterity of finger movements, but the association with muscle strength suggests that it may be influenced in part by preferential use of one hand for tasks which strengthen the FDI muscle.

Adult↗
PubMed1999

Evaluation of short-term precision for tibial ultrasonometry.

Tibial quantitative ultrasonometry is a relatively novel technique in the field of bone sonometry, an emerging alternative to bone densitometry. The implementation of this technique in a pediatric population could prove valuable from a clinical as well as a research viewpoint. In clinical practice it is necessary to know the precision of this technique and the possible influence on measurements before implementation. This study presents the precision in a Caucasian pediatric population and the influence of measurement site, dexterity, brand of coupling gel, and temperature of coupling gel. To assess intra- and interobserver variance duplicate measurements, with repositioning, ultrasonometry was performed in 10 children over a short period of time. The observers were blinded for the results of the other observer and after each measurement the skin markings were removed. Intraobserver variance for operator one (MHL) and for observer two (SFGR) was CV 0.43%. The interobserver variance was CV 0.61%. Left midtibial and right midtibial speed of sound (SOS) measurements showed no significant differences. There were, however, significant differences in both boys and girls between right proximal versus right midtibial, right midtibial versus right distal, and right proximal versus right distal (for all P < 0.001). One-way analysis of variance (ANOVA) showed that neither the use of different coupling gels nor an increase in gel temperature had a significant influence on measurements. The results of our study show that tibial quantitative ultrasonography (QUS) is a highly reproducible technique in a Caucasian pediatric population.

Adolescent↗
PubMed2003

Robotic assisted microsurgical vasal reconstruction in a model system.

Our objective was to determine whether or not male reproductive microsurgery is adaptable to current robotic technology. We devised a model vas deferens system using rat vasa deferentia and completed vasal anastomosis with full-thickness and mucosal robotically placed, Sharpoint 10-0 bicurve nylon sutures. Experienced and inexperienced microsurgeons performed separate anastomoses. Both groups of microsurgeons completed anastomoses with accuracy and enhanced comfort. The robotic graspers had the dexterity to delicately handle the 10-0 sutures and needles. We conclude that through our model vas deferens system, we demonstrated the feasibility of applying robotic technology to male reproductive microsurgery. This pilot study reveals some advantages of the robot and suggests future use of this system in a new urological application domain.

Anastomosis, Surgical↗
PubMed1998

Pilot neuropsychological findings from a treatment regimen consisting of intensive chemotherapy and bone marrow rescue for young children with newly diagnosed malignant brain tumors.

Ten children (6 girls and 4 boys) who completed a protocol in which their localized brain tumors were successfully treated without cranial irradiation were referred for neuropsychological assessment. At the time of testing, they were disease free without any neuroaxis dissemination or leptomeningeal disease. Tumor types included pineoblastoma, glioblastoma, ependymoma, PNET and medulloblastoma. They had a mean age of 5 years and 8 months (SD = 1.86; range = 2.1-8.9 years) and were an average of 37.8 months post bone marrow transplant (SD = 16.42; range = 14-58 months). Neuropsychological data from this study reveal that the mean scores for this nonradiated group of children were within the average range for the following domains: academic achievement tests of reading, spelling and mathematics, verbal and visual memory, visual-motor integration, social-emotional and behavioral functioning. Furthermore, this group of children were performing within the low average range of overall Intelligence, as well as both verbal IQ/verbal reasoning and performance IQ/abstract visual reasoning. On tasks of fine motor dexterity, this group was within the low average range when using their dominant hand; however, they performed within the borderline range when using their non-dominant hand. Of note, this group of children demonstrated significant deficits within the borderline to impaired ranges on language tasks of expressive picture naming and receptive picture vocabulary.

Achievement↗
PubMed2005

Fine motor function and neuropsychological deficits in individuals at risk for schizophrenia.

Deficits in fine motor function and neuropsychological performance have been described as risk factors for schizophrenia. In the Basel FEPSY study (Früherkennung von Psychosen; English: Early Detection of Psychosis) individuals at risk for psychosis were identified in a screening procedure (Riecher-Rössler et al. 2005). As a part of the multilevel assessment, 40 individuals at risk for psychosis and 42 healthy controls matched for age, sex and handedness were investigated with a fine motor function test battery and a neuropsychological test battery. Individuals at risk showed lower performances in all subtests of the fine motor function tests, predominantly in dexterity and velocity (wrist/fingers and arm/hand). In the neuropsychological test battery, individuals at risk performed less well compared to healthy controls regarding sustained attention, working memory and perseveration. The combined evaluation of the two test batteries (neuropsychological and fine motor function) separates the two groups into individuals at risk and healthy controls better than each test battery alone. A multilevel approach might therefore be a valuable contribution to detecting beginning schizophrenia.

Adult↗
PubMed2001

Motor cortex plasticity during forced-use therapy in stroke patients: a preliminary study.

Treatment-induced plastic changes were investigated in the brains of stroke patients in the subacute stage of illness. Nine patients participated in 1 week of conventional physiotherapy. In the subsequent week conventional physiotherapy was combined with forced-use therapy. Focal transcranial magnetic stimulation was used to determine the motor output areas of the abductor pollicis brevis muscles prior to the treatment and after the first and after the second week. Motor performance was evaluated using the Nine Hole Peg Test, the Frenchay Arm Test and vigorometry to measure the grip strength. Before treatment the cortical representation area of the paretic hand muscle was significantly smaller than the contralateral side. This difference persisted after the first week of physiotherapy. In contrast, the motor output map in the affected hemisphere was significantly enlarged after forced-use therapy. This increase in motor cortex excitability was accompanied by a significant improvement in dexterity. Across the two treatment weeks the centres of the motor output maps shifted significantly stronger in the affected hemisphere than in unaffected hemisphere, suggesting the recruitment of adjacent brain areas. We conclude that the combination of forced-use therapy and conventional physiotherapy enhances motor cortex excitability and improves motor performance compared to a preceding conventional physiotherapy alone. Due to the small number of patients and the lack of a control group, these results are preliminary observations and require replication in a larger sample.

Aged↗
PubMed2002

Bradykinesia in Huntington's disease. A prospective, follow-up study.

Bradykinesia is a frequent finding in Huntington's disease (HD), but some aspects are presently unknown; including the natural evolution of bradykinesia over time and the correlation between bradykinesia and functional capacity. We studied the motor performance of 20 genetically confirmed patients with HD (age: 40+/-10.8 years; age at onset 33.6+/-11 years; total functional capacity (TFC): 9.57+/-3; UHDRS total motor scale: 31.4+/-13, triplet length (CAG)n: 46.7+/-4 triplets). These patients were studied in baseline conditions and after 18.7+/-6 months of follow-up. In addition, HD patients were compared with 20 age-matched normal controls. Motor study included the four CAPIT timed tests commonly used for Parkinson's disease: pronation-supination (PS), finger dexterity (FD), movement between two points (MTP) and walking test (WT). HD patients were significantly slower than controls in all motor tasks. A significant deterioration occurred over time in three of the four motor tasks (especially FD and WT). A significant correlation between timed tests and TFC score was found (for MTP, r: -0.845; p < 0,0001). In addition a significant correlation between timed tests and the UHDRDS total motor scale was also found (for MTP, r: 0.864; p < 0.0001). In conclusion, simple timed motor tests can detect a deterioration of motor activity over time in HD. Timed tests might be useful to follow the natural evolution of HD and to assess the efficacy of new therapies.

Adult↗
PubMed2000

Methylmercury exposure affects motor performance of a riverine population of the Tapajós river, Brazilian Amazon.

Gold mining and deforestation in the Brazilian Amazon are increasing mercury pollution of the extensive water system, exposing riverine populations to organic mercury through fish-eating. The aim of the present study was to evaluate the effect of such exposure on motor performance. This cross-sectional study was carried out in May 1996, in a village located on the banks of the Tapajós river in the Amazonian Basin, Brazil. Information concerning sociodemographics, health, smoking habits, alcohol drinking, dietary habits and work history were collected using an interview-administered questionnaire. Mercury concentrations were measured by cold vapor atomic absorption in blood and hair of each participant, of whom those aged between 15 and 79 years were assessed for motor performance (n = 84). Psychomotor performance was evaluated using the Santa Ana manual dexterity test, the Grooved Pegboard Fine motor test and the fingertapping motor speed test. Motor strength was measured by dynamometry for grip and pinch strength. Following the exclusion of 16 persons for previous head injury, working with mercury in the goldmining sites, or for diabetes, the relationship between performance and bioindicators of mercury was examined using multivariate statistical analyses, taking into account covariables. All participants in the study reported eating fish, which comprised 61.8% of the total meals eaten during the preceding week. The median hair total mercury concentration was 9 microg/g. Organic mercury accounted for 94.4 = 1.9% of the total mercury levels. Multivariate analysis of variance indicated that hair mercury was inversely associated with overall performance on the psychomotor tests, while a tendency was observed with blood mercury. Semipartial regression analyses showed that hair total mercury accounted for 8% to 16% of the variance of psychomotor performance. Neither hair nor blood total mercury was associated with the results of the strength tests in women and men. Although dose-effect relationships were observed in this cross-sectional study, they may reflect higher exposure levels in the past. The findings of this study demonstrated neurobehavioral manifestations of subtle neurotoxic effects on motor functions, associated with low-level methylmercury exposure.

Adolescent↗
PubMed1998

Neurological and functional effects of short-term exposure to hand-arm vibration.

OBJECTIVE: The aim of the present study was to quantify the sensory and functional effects resulting from a short-duration (30 min) exposure to hand-arm vibration. SUBJECTS AND METHODS: Nine subjects went through nine laboratory experiments. For 32 min they grasped a handle vibrating at three different amplitudes (5, 20, and 80 ms-2) and at three frequencies (31.5, 125, and 500 Hz). Additionally, a reference experiment was conducted in which the handle did not vibrate. Three sensory tests [vibration perception threshold (VPT), pressure perception threshold (PPT), and distal sensory latency time (DSL)], two functional tests [Purdue peg-board (PPB) and maximal voluntary force (MVF)], and a questionnaire concerning the perceived paresthesia and numbness were completed before, during, and after exposure. RESULTS: A 32-min period of exposure to vibration leads to a temporary threshold shift (TTS) of the VPT and to the development of paresthesia and numbness. The VPT appears to vary with the exposure duration according to a first-order model with a time constant about equal to 3 min. The TTS increases with the vibration acceleration amplitude and is greater for an exposure frequency of 125 Hz than for that of 31.5 or 500 Hz. It is also greater at the test frequency 125 Hz than at 31.5 Hz. The other tests do not demonstrate any significant variation. In particular, the PPB test does not demonstrate any loss of dexterity. CONCLUSION: After some 30 min of exposure to vibration the VPTs are increased and paresthesia and numbness develop. However, these do not appear to influence significantly the capacity or performance at work.

Adult↗
PubMed2001

Musculoskeletal complaints, functional capacity, personality and psychosocial factors.

OBJECTIVES: The aim of the research was to study the association between psychosocial and personality factors, and neck and wrist-hand musculoskeletal complaints, taking account of the occupational factors of force, posture and repetitiveness, and non-occupational risk factors such as sport, hobbies, medical history. METHODS: During personal interviews 133 women from seven different companies, working at constraining workplaces (very repetitive work), answered several questionnaires. These concerned: personal characteristics and history; work characteristics; psychosocial factors (perception and appreciation of the work situation, satisfaction at work, stress symptoms, Karasek questionnaire) and personality factors (neuroticism, conscientiousness, type-A behavior). They also undertook functional and psychomotor tests (wrist angles, grip strength and a dexterity test). Logistic regression models were calculated. RESULTS: Wrist-hand complaints appear to be associated with some personal characteristics (smoking habits, fewer hobbies), work constraints (fewer breaks, heavy lifting efforts) and some personality (introversion) and psychosocial factors (worse appreciation of work). Neck complaints are also associated with some personal characteristics (young people, small, bad health, hormonal problems, fewer hobbies), some personality (urgency of time) and psychosocial factors (constraints as seen by the supervisor). CONCLUSION: The study confirms the multifactorial character of the musculoskeletal disorders and underlines the need for a global ergonomic approach to work situations, taking into account all their physical, psychological and social components.

Adult↗
PubMed2000

Augmentation of blood circulation to the fingers by warming distant body areas.

Future activities in space will require greater periods of time in extreme environments in which the body periphery will be vulnerable to chilling. Maintaining the hands and fingers in comfortable conditions enhances finger flexibility and dexterity, and thus effects better work performance. We have evaluated the efficacy of promoting heat transfer and release by the extremities by increasing the blood flow to the periphery from more distant parts of the body. The experimental garment paradigm developed by the investigators was used to manipulate the temperature of different body areas. Six subjects, two females and four males, were evaluated in a stage-1 baseline condition, with the inlet temperature of the circulating water in the liquid cooling/warming garment (LCWG) at 33 degrees C. At stage 2 the total LCWG water inlet temperature was cooled to 8 degrees C, and at stage 3 the inlet water temperature in specific segments of the LCWG was warmed (according to protocol) to 45 degrees C, while the inlet temperature in the rest of the LCWG was maintained at 8 degrees C. The following four body-area-warming conditions were studied in separate sessions: (1) head, (2) upper torso/arm, (3) upper torso/arm/head, and (4) legs/feet. Skin temperature, heat flux and blood perfusion of the fingers, and subjective perception of thermal sensations and overall physical comfort were assessed. Finger temperature (T(fing)) analyses showed a statistically significant condition x stage interaction. Post-hoc comparisons (T(fing)) indicated that at stage 3, the upper torso/arm/head warming condition was significantly different from the head, upper torso/arm and legs/feet conditions, showing an increase in T(fing). There was a significant increase in blood perfusion in the fingers at stage 3 in all conditions. Subjective perception of hand warmth, and overall physical comfort level significantly increased in the stage 3 upper torso/arm/head condition. The findings indicate that physiological methods to enhance heat transfer by the blood to the periphery within protective clothing provide an additional tool for increasing total and local human comfort in extreme environments.

Adult↗