Encoding Manual Dexterity through Modulation of Intrinsic α Band Connectivity.

The human hand possesses both consolidated motor skills and remarkable flexibility in adapting to ongoing task demands. However, the underlying mechanisms by which the brain balances stability and flexibility remain unknown. In the absence of external input or behavior, spontaneous (intrinsic) brain connectivity is thought to represent a prior of stored memories. In this study, we investigated how manual dexterity modulates spontaneous functional connectivity in the motor cortex during hand movement. Using magnetoencephalography, in 47 human participants (both sexes), we examined connectivity modulations in the α and ß frequency bands at rest and during two motor tasks (i.e., finger tapping or toe squeezing). The flexibility and stability of such modulations allowed us to identify two groups of participants with different levels of performance (high and low performers) on the nine-hole peg test, a test of manual dexterity. In the α band, participants with higher manual dexterity showed distributed decreases of connectivity, specifically in the motor cortex, increased segregation, and reduced nodal centrality. Participants with lower manual dexterity showed an opposite pattern. Notably, these patterns from the brain to behavior are mirrored by results from behavior to the brain. Indeed, when participants were divided using the median split of the dexterity score, we found the same connectivity patterns. In summary, this experiment shows that a long-term motor skill-manual dexterity-influences the way the motor systems respond during movements.

Transcranial magnetic stimulation over supramarginal gyrus stimulates primary motor cortex directly and impairs manual dexterity: implications for TMS focality.

Based on human motor cortex, the effective spatial resolution of transcranial magnetic stimulation (TMS) is often described as 5-20 mm, because small changes in TMS coil position can have large effects on motor-evoked potentials (MEPs). MEPs are often studied at rest, with muscles relaxed. During muscle contraction and movement, corticospinal excitability is higher, thresholds for effective stimulation are lower, and MEPs can be evoked from larger regions of scalp, so the effective spatial resolution of TMS is larger. We found that TMS over the supramarginal gyrus (SMG) impaired manual dexterity in the grooved pegboard task. It also resulted in short-latency MEPs in hand muscles, despite the coil being 55 mm away from the motor cortex hand area (M1). MEPs might be evoked by either a specific corticospinal connection from SMG or a remote but direct electromagnetic stimulation of M1. To distinguish these alternatives, we mapped MEPs across the scalp during rest, isotonic contraction, and manual dexterity tasks and ran electric field simulations to model the expected M1 activation from 27 scalp locations and four coil orientations. We also systematically reviewed studies using TMS during movement. Across five experiments, TMS over SMG reliably evoked MEPs during hand movement. These MEPs were consistent with direct M1 stimulation and substantially decreased corticospinal thresholds during natural movement. Systematic review suggested that 54 published experiments may have suffered from similar motor activation confounds. Our results have implications for the assumed spatial resolution of TMS, and especially when TMS is presented within 55 mm of the motor cortex.NEW & NOTEWORTHY Transcranial magnetic stimulation (TMS) is often described as having an effective spatial resolution of ∼10 mm, because of the limited area of the scalp on which TMS produces motor-evoked potentials (MEPs) in resting muscles. We find that during natural hand movement TMS evokes MEPs from a much larger scalp area, in particular when stimulating over the supramarginal gyrus 55 mm away. Our results show that TMS can be effective at much larger distances than generally assumed.

The Finger Dexterity Test: Validation study of a smartphone-based manual dexterity assessment.

BACKGROUND: The Nine-Hole Peg Test (9HPT) is the golden standard to measure manual dexterity in people with multiple sclerosis (MS). However, administration requires trained personnel and dedicated time during a clinical visit. OBJECTIVES: The objective of this study is to validate a smartphone-based test for remote manual dexterity assessment, the icompanion Finger Dexterity Test (FDT), to be included into the icompanion application. METHODS: A total of 65 MS and 81 healthy subjects were tested, and 20 healthy subjects were retested 2 weeks later. RESULTS: The FDT significantly correlated with the 9HPT (dominant: ρ = 0.62, p < 0.001; non-dominant: ρ = 0.52, p < 0.001). MS subjects had significantly higher FDT scores than healthy subjects (dominant: p = 0.015; non-dominant: p = 0.013), which was not the case for the 9HPT. A significant correlation with age (dominant: ρ = 0.46, p < 0.001; non-dominant: ρ = 0.40, p = 0.002), Expanded Disability Status Scale (EDSS, dominant: ρ = 0.36, p = 0.005; non-dominant: ρ = 0.31, p = 0.024), and disease duration for the non-dominant hand (ρ = 0.31, p = 0.016) was observed. There was a good test-retest reliability in healthy subjects (dominant: r = 0.69, p = 0.001; non-dominant: r = 0.87, p < 0.001). CONCLUSIONS: The icompanion FDT shows a moderate-to-good concurrent validity and test-retest reliability, differentiates between the MS subjects and healthy controls, and correlates with clinical parameters. This test can be implemented into routine MS care for remote follow-up of manual dexterity.

Explaining the influence of practice on the grooved pegboard times of older adults: role of force steadiness.

The purpose was to identify the variables that can explain the variance in the grooved pegboard times of older adults categorized as either fast or slow performers. Participants (n = 28; 60-83 years) completed two experimental sessions, before and after 6 practice sessions of the grooved pegboard test. The 2 groups were identified based on average pegboard times during the practice sessions. Average pegboard time during practice was 73 ± 11 s for the fast group and 85 ± 13 s for the slow group. Explanatory variables for the pegboard times before and after practice were the durations of 4 peg-manipulation phases and 12 measures of force steadiness (coefficient of variation [CV] for force) during isometric contractions with the index finger abductor and wrist extensor muscles. Time to complete the grooved pegboard test after practice decreased by 25 ± 11% for the fast group and by 28 ± 10% for the slow group. Multiple regression models explained more of the variance in the pegboard times for the fast group before practice (Adjusted R2 = 0.85) than after practice (R2 = 0.51), whereas the variance explained for the slow group was similar before (Adjusted R2 = 0.67) and after (Adjusted R2 = 0.64) practice. The explanatory variables differed between before and after practice for the fast group but only slightly for the slow group. These findings indicate that performance-based stratification of older adults can identify unique adjustments in motor function that are independent of chronological age.

Evidence-Based Physiotherapeutic Interventions Enhancing Hand Dexterity, Activities of Daily Living and Quality of Life of Parkinson's Disease Patients: A Systematic Review.

OBJECTIVES: This systematic review primarily aims to identify the optimal physiotherapeutic intervention to improve hand dexterity in Parkinson's Disease (PD) patients. The secondary objectives were to identify the hand dexterity physiotherapeutic interventions available for PD patients, and to determine the quality of these interventions. REVIEW METHODS: Eight electronic databases were systematically searched to identify relevant randomized controlled trial full-text articles using the established search strategy. The primary outcomes of interest were measurements for hand dexterity and activities of daily living (ADL). RESULTS: A total of 11 studies comprising 647 participants with PD were included. Most studies had a high risk of performance bias and an unclear risk of selection bias. The intervention training period ranged from a single session to 12 weeks. Compared to their respective control group, eight out of 11 studies revealed significant results in hand dexterity, two out of three studies reported positive effects on ADL, four of seven studies showed significant improvements in upper limb motor performance, and two studies perceived positive benefits in terms of overall quality of life. Five out of 11 studies that recorded the occurrence of adverse events reported no adverse events post-intervention. CONCLUSION: The dearth of evidence made it difficult to support any one intervention as the best intervention when compared to the other PD treatments in upper limb rehabilitation. Regardless, a home-based dexterity rehabilitation programme is still a promising approach to enhance dexterity-related functional abilities.

The application of heating film to hands reduces the decline in manual dexterity performance associated with cold exposure.

PURPOSE: Exposure to cold temperatures decreases finger temperature (Tfing) and dexterity. Decreased manual function and dexterity can be serious safety risks, especially in tasks that require fine motor movements that must be performed outdoors. The aim of this study was to determine whether hand heating with a minimal power requirement (14.8 W) results in a smaller reduction in Tfing and manual dexterity performance during mild cold exposure compared to a non-heated control condition. METHODS: In a randomized crossover design, twenty-two healthy participants were exposed to a moderately cold environment (5  ºC) for 90 min. One condition had no intervention (CON), while the other had the palmar and dorsal hands heated (HEAT) by using electric heating films. Tfing and cutaneous vascular conductance (CVC) were continuously monitored using laser Doppler flowmetry. Manual dexterity performance and cognitive function were assessed by the Grooved Pegboard Test (GPT) and Stroop Color-Word (SCW) test, respectively, during the baseline period and every 30 min during the cold exposure. RESULTS: After the cold exposure, Tfing was higher in HEAT relative to CON (CON 9.8 vs. HEAT 13.7 ºC, p < 0.0001). GPT placing time, as an index of dexterity performance, was also shorter in HEAT by 14.5% (CON 69.10 ± 13.08 vs. HEAT 59.06 ± 7.99 s, p < 0.0001). There was no difference in CVC between the two conditions during the cold exposure (p > 0.05 for all). Cognitive function was similar between two conditions (p > 0.05 for all). CONCLUSION: The proposed hand heating method offers a practical means of heating fingers to maintain dexterity throughout prolonged cold exposure.

Manual preference, performance, and dexterity for bimanual grass-feeding behavior in wild geladas (Theropithecus gelada).

We assessed whether wild geladas, highly specialized terrestrial grass eaters, are lateralized for bimanual grass-plucking behavior. According to the literature, we expected that complex motor movements in grass feeding would favor the emergence of a population-level hand bias in these primates. In addition, we described geladas' manual behavior based on systematic observations of several individuals. Our study group included 28 individuals belonging to a population of free-ranging geladas frequenting the Kundi plateau, Ethiopia. We filmed monkeys while feeding on grass, and hand preference and performance were coded. Geladas performed more plucking movements per second with their left hand (LH) compared to the right one and preferred their LH both to start and finish collection bouts. Also, the rhythmic movements of each hand had a significant tendency toward isochrony. Finally, geladas used forceful pad-to-pad precision grips, in-hand movements, and compound grips to pluck and collect grass blades, considered the most advanced manual skills in primate species. The LH's leading role suggests an advantage of the right hemisphere in regulating geladas' bimanual grass-feeding behavior. The tactile input from the hands and/or rhythmic hand movements might contribute to explaining this pattern of laterality. Our findings highlighted the importance of adopting multiple laterality measures to investigate manual laterality. Moreover, the need to speed up the execution time of manual foraging might be a further important factor in studying the evolution of manual laterality and dexterity in primates.

Classification of Mild Cognitive Impairment and Alzheimer's Disease Using Manual Motor Measures.

INTRODUCTION: Manual motor problems have been reported in mild cognitive impairment (MCI) and Alzheimer's disease (AD), but the specific aspects that are affected, their neuropathology, and potential value for classification modeling is unknown. The current study examined if multiple measures of motor strength, dexterity, and speed are affected in MCI and AD, related to AD biomarkers, and are able to classify MCI or AD. METHODS: Fifty-three cognitively normal (CN), 33 amnestic MCI, and 28 AD subjects completed five manual motor measures: grip force, Trail Making Test A, spiral tracing, finger tapping, and a simulated feeding task. Analyses included (1) group differences in manual performance; (2) associations between manual function and AD biomarkers (PET amyloid ß, hippocampal volume, and APOE ε4 alleles); and (3) group classification accuracy of manual motor function using machine learning. RESULTS: Amnestic MCI and AD subjects exhibited slower psychomotor speed and AD subjects had weaker dominant hand grip strength than CN subjects. Performance on these measures was related to amyloid ß deposition (both) and hippocampal volume (psychomotor speed only). Support vector classification well-discriminated control and AD subjects (area under the curve of 0.73 and 0.77, respectively) but poorly discriminated MCI from controls or AD. CONCLUSION: Grip strength and spiral tracing appear preserved, while psychomotor speed is affected in amnestic MCI and AD. The association of motor performance with amyloid ß deposition and atrophy could indicate that this is due to amyloid deposition in and atrophy of motor brain regions, which generally occurs later in the disease process. The promising discriminatory abilities of manual motor measures for AD emphasize their value alongside other cognitive and motor assessment outcomes in classification and prediction models, as well as potential enrichment of outcome variables in AD clinical trials.

Influence of visual acuity, manual dexterity and handgrip strength on oral and denture hygiene ability of non-frail older people: Development of the Gerostomatological Assessment Battery.

BACKGROUND: Due to the heterogeneity of older people, it is difficult to identify reliable factors influencing oral health. OBJECTIVE: The aim was to illustrate the influence of visual acuity, manual dexterity, and handgrip strength on the oral and denture hygiene ability of older non-frail people. METHODS: In a cross-sectional study, conducted at a specialized dental clinic, at baseline, all participants received professional prophylaxis and instruction on daily oral and denture hygiene regimes for a 6-week intervention period. Data on the Quigley and Hein modified plaque index (QHI), respectively, the Denture Hygiene Index (DHI), visual acuity, manual dexterity and handgrip strength in non-frail participants (≥ 65 years) were collected. Recruitment was done within the clinic's patient clientele and within the staff (control cohort). RESULTS: Women showed significantly better manual dexterity than men (Mann-Whitney U, p = .01), while women's mean handgrip strength was significantly lower (Mann-Whitney U, p < .01). Manual dexterity (Mann-Whitney U, p = .003) and handgrip strength (Mann-Whitney U, p = .052) were associated with age. However, visual acuity, manual dexterity and handgrip strength had no influence on oral or denture hygiene. CONCLUSION: Visual acuity, manual dexterity and handgrip strength have no influence on oral and denture hygiene ability in older non-frail people. Further studies should investigate whether these factors also have no influence on oral and denture hygiene in vulnerable older patients. Therefore, an assessment tool for the evaluation of potential influencing factors of oral and denture hygiene is proposed in a dental context. This Gerostomatological Assessment Battery (G-AB) can be used as a helpful tool to check the individual cognitive function and comprehension, dental therapy approaches and their individual adaption.

Action observation plus motor imagery and somatosensory discrimination training are effective non-motor approaches to improve manual dexterity.

BACKGROUND: Action observation plus motor imagery (AOMI) and somatosensory discrimination training (SSDT) represent sensory input-based approaches to train the motor system without necessarily asking subjects to perform active movements. PURPOSE: To investigate AOMI and SSDT effects compared to no intervention on manual dexterity in healthy subjects. STUDY DESIGN: Randomized controlled study. METHODS: Sixty healthy right-handed participants were randomized into AOMI, SSDT or Control (CTRL) groups. AOMI observed video-clips including right-hand dexterity tasks and concurrently performed motor imagery, SSDT performed surfaces recognition and 2-point distance discrimination tasks with the right hand, whereas CTRL underwent no intervention. A blinded physiotherapist assessed participants for manual dexterity using the Purdue Pegboard Test (Right hand-R, Left hand-L, Both hands-B, R+L+B and assembly tasks) at baseline (T0) and training end (T1). A mixed-design Analysis of Variance with Time as within-subject factor and Group as between-subject factor was used to investigate between-group differences over time. RESULTS: A Time by Group interaction and Time effect were found for R task, which increased from T0 to T1 in all groups with very large effect sizes for SSDT (d = 1.8, CI95 2.4-1.0, P < .001) and AOMI (d = 1.7, CI95 2.5-1.0, P < .001) and medium effect size for CTRL (d = 0.6, CI95 1.2-0.2, P < .001). Between-group post-hoc comparison for deltas (T1-T0) showed large effect size (d = 1.0, CI95 1.6-0.3, P = .003) in favor of SSDT and medium effect size (d = 0.7, CI95 1.4-0.1, P = .026) in favor of AOMI compared to CTRL. Time effects were found for L, B, R + L + B and assembly tasks (P < .001). CONCLUSIONS: AOMI and SSDT induced greater manual dexterity improvements than no intervention. These findings supported the role of visual and somatosensory stimuli in building a motor plan and enhancing the accuracy of hand movements. These non-motor approaches may enhance motor performance in job or hobbies requiring marked manual dexterity.

Evaluation of manual dexterity when using a mirror of dental students and academicians with increasing professional experience.

INTRODUCTION: To evaluate the manual dexterity of dentistry students and academicians when using a mirror according to increasing professional experience. MATERIALS AND METHODS: The study included 72 subjects, grouped according to professional experience 5th year dentistry students (DS) accepted as no experience-academicians with 1-4 years experience (A5L)-academicians with ≥5 years experience (A5M). Direct and indirect visualisation using the mirror was evaluated with the completion times of the O'Connor Finger Dexterity Test. RESULTS: The hand grip strength values of both left and right hand were found to be statistically significantly higher in all the males than in the females (p < .05). The indirect test times (ITT) using the mirror were significantly longer for males than for females (p = .001), and no significant difference was determined between the genders in the direct test times (DTT) (p > .05). For all the study participants, DTT shortened as professional experience increased (p < .05). In addition, the mean values of both DTT (p = .031) and ITT (p = .028) in the DS group were statistically significantly longer than the A5M group. CONCLUSION: With increasing professional experience, manual dexterity was determined to increase, and females were found to be more successful in the direct manual dexterity tests independently of the groups. The statistical significance between the DS and A5M groups, especially in the hand dexterity test with a mirror, shows the importance of experience. The study results demonstrated that professional manual dexterity in dentistry can be developed with increasing practical application.

Effectiveness of a manual test at the beginning of dental school.

INTRODUCTION: This study analysed whether the SAZAMED (Self-assessment for dentistry studies) manual test conducted as an exercise or examination in the first year of dental studies, and the official aptitude test for medical studies (EMS), can predict future performance of dental students. MATERIALS AND METHODS: Students enrolled in the dental curriculum at the University of Basel between 2009/10 and 2019/20 were categorized: Group A conducted the SAZAMED in the third bachelor year (BA) and second master year (MA), group B practiced in the first and third BA and second MA and group C had to pass the test in the first BA with repetition in the third BA and second MA. SAZAMED comprised (i) wire bending, (ii) modelling sphere and cube, (iii) drawing mirror-inverted and (iv) indirect drawing over a mirror. Comparative variables were the EMS per cent rank and test scores in practical-clinical examinations in the third BA and the second MA. RESULTS: Data were available from 329 students over the 10-year period. Repeaters and dropouts had poorer performance in the first BA SAZAMED than students who did not (p < 0.001). Among the four SAZAMED exercises, mirror-inverted drawing was the strongest predictor of future student performance. The official aptitude test EMS correlated with the third BA certificate (p = 0.012), but failed to predict repeaters and dropouts. CONCLUSION: Since academic success was associated with significantly better scores on the first BA SAZAMED, it is considered a predictor and recommended in addition to the official EMS to identify students in need of intervention programmes or who should choose a different field of study.

Don't plan, just do it: Cognitive and sensorimotor contributions to manual dexterity.

Manual dexterity is referred to as the skill to perform fine motor movements and it has been assumed to be associated to the cognitive domain, as well as the sensorimotor one. In this work, we investigated with functional near-infrared spectroscopy the cortical activations elicited by the execution of the 9-HPT, i.e., a standard test evaluating manual dexterity in which nine pegs were taken, placed into and then removed from nine holes on a board as quickly as possible. For comparison, we proposed a new active control task mainly involving the sensorimotor domain, in which the pegs must be placed and removed using the same single hole (1-HPT). Behaviorally, we found two distinct groups based on the difference between the execution time of the 9-HPT and the 1-HPT (ΔHPT). Cortical areas belonging to the network controlling reaching and grasping movements were active in both groups; however, participants showing a large ΔHPT presented significantly higher activation in prefrontal cortical areas (right BA10 and BA11) during 9-HPT and 1-HPT performance with respect to the participants with a small ΔHPT, who showed a deactivation in BA10. Unexpectedly, we observed a significant linear relationship between ΔHPT and right BA10 activity. This suggested that participants performing the 9-HPT more slowly than the 1-HPT recruited prefrontal areas implicitly exploiting the cognitive skills of planning, perhaps in search of a motor strategy to solve the test activating attentional and cognitive control processes, but this resulted not efficient and instead increased the time to accomplish a manual dexterity task.

Assessment of sensorimotor and strength related function of breast cancer patients during systemic drug therapy: a prospective observational study.

BACKGROUND: Chemotherapy is a well-known risk factor for sensorial and motor disturbances. Chemotherapy induced peripheral neuropathy (CIPN) which predominantly affects sensory nerves might cause a diminished fine motor function. This prospective observational study aimed to assess the sensorimotor functions of breast cancer patients before, during, and after chemotherapy. METHODS: A total of 56 breast cancer patients were evaluated at three different times as follows: T1 (before chemotherapy), T2 (middle chemotherapy), and T3 (completion of chemotherapy). Motor function was assessed with handgrip strength (HGS), peripheral muscle strength (PMS), and the Minnesota Manual Dexterity Test (MMDT). Semmes Weinstein Monofilament Test (SWMT) was performed to assess the sensory function. Fatigue was evaluated with the European Organization for Research and Treatment of Cancer Quality of Life Module Cancer Related Fatigue (EORTC-QLQ-FA12), respectively. RESULTS: HGS and MMDT were found significant (χ2: 11.279, p = 0.004 and χ2: 9.893, p = 0.007, respectively) whereas PMS was not found significant (F (2,110) = 1.914, p = 0.152). Pairwise comparisons with Bonferroni adjustments revealed that HGS was found significant between T1 and T3, while significant results were obtained between T1 and T2 as well as T2 and T3 in MMDT (p = 0.01 and p = 0.042). There were significant results in some reference points of SWMT, though they were not found after pairwise comparisons with Bonferroni adjustment (p > 0.05). Fatigue was found significantly increased from T1 through T3 (Median: 19.44 vs 27.77, z: -2.347, p = 0.019, Wilcoxon test). CONCLUSION: Our study showed that decreased handgrip strength and fine motor function, as well as increased fatigue, are evident during the chemotherapy. SWMT can be an optional assessment in the context of tracking changes in cutaneous sensation during chemotherapy due to its non-invasive, cheap, and easily repeatable features among cancer patients. To preserve functional capacity as well as independence in daily living, precautions and follow up assessments during the systemic therapy process should be integrated as early as possible to prevent future deteriorations in daily life for patients who undergo chemotherapy. TRIAL REGISTRATION: NCT04799080.

The effect of subthalamic nucleus deep brain stimulation and dopaminergic treatment on dual-task manual dexterity in Parkinson's disease.

BACKGROUND AND PURPOSE: Dual-task manual dexterity is required to perform activities of daily living and is affected by cognitive functions. This study aimed to investigate the effects of two main treatment options, subthalamic nucleus deep brain stimulation (STN-DBS) and dopaminergic treatment (DT), on dual-task manual dexterity and cognitive functions of people with Parkinson's disease (PwPD). METHODS: Twenty-one PwPD were assessed in four different conditions as medication "on-off" and STN-DBS "on-off" in random order. Motor symptoms were measured with the Movement Disorder Society-Unified Parkinson Disease Rating Scale, motor section (MDS-UPDRS-III). Single and dual-task manual dexterity was assessed with the Nine-Hole Peg Test (NHPT) and cognitive functions were assessed with the Stroop Test (ST) and the Trail Making Test (TMT). RESULTS: Both DT and STN-DBS enhanced MDS-UPDRS-III, and the combination of DT and STN-DBS provided further improvement. Only STN-DBS enhanced dominant hand single-task NHPT scores. Non-dominant single-task NHPT scores and dual-task NHPT scores improved with both treatments alone; however, STN-DBS resulted in more improvement than DT. Dual-task interference, ST, and TMT scores improved with both treatments alone; however, combining DT and STN-DBS did not provide more improvement. CONCLUSION: DT, STN-DBS, and combining both treatments have different effects on motor symptoms, single and dual-task manual dexterity, dual-task interference, and cognitive functions. These results indicate that DT and STN-DBS may affect motor and cognitive functions via different mechanisms. Effects of DT and STN-DBS on manual dexterity may depend on the degree of cognitive involvement in manual dexterity tasks.

Effect of Proprioceptive Training Compared With Other Interventions for Upper Limb Deficits in People With Parkinson Disease: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

OBJECTIVE: This systematic review and meta-analysis aimed to determine the efficacy of proprioceptive training on hand dexterity, upper limb function, and quality of life (QoL) in people with Parkinson disease (PD) compared with no or other active interventions. DATA SOURCES: Medline PubMed, Cochrane Library, CINAHL, PEDro, and Web of Science databases were searched to identify published studies until February 2023. STUDY SELECTION: Peer-reviewed English publications of randomized controlled trials (RCTs) of proprioceptive training conducted among people with PD. DATA EXTRACTION: Study characteristics, exercise program type and dosage, outcome of interest, and between-group comparisons of post-test results of intervention and comparison groups. DATA SYNTHESIS: Eight RCTs were included, involving 344 people with PD. Six RCTs contributed to meta-analyses. There was very low certainty of evidence that proprioceptive training may improve dominant hand (standard mean difference [SMD] 0.34, 95% CI 0.08-0.60, P=.01) and non-dominant hand (SMD 0.36, 95% CI 0.10-0.63, P<.01) fine motor dexterity, and dominant hand gross manual dexterity (SMD 1.73, 95% CI 0.30-3.16, P=.02), following 2-8 weeks of proprioceptive training. There was no evidence of effects on non-dominant hand gross manual dexterity, upper limb function, and QoL after proprioceptive training. CONCLUSIONS: Findings regarding the effect of proprioceptive training on hand dexterity in the short-term are inconclusive. The small sample size likely limited effect detection. Future large RCTs should compare proprioceptive training with no intervention and perform comprehensive biomechanical analysis to gain a clearer idea of its effects. Incorporating longer-duration proprioceptive training programs is also recommended to investigate long-lasting effects.

Aging reduces manual dexterity and force production asymmetries between the hands.

Age-related effects on motor asymmetry provide insight into changes in cortical activation during aging. To investigate potential changes in manual performance associated with aging, we conducted the Jamar hand function test and the Purdue Pegboard test on young and older adults. All tests indicated reduced motor asymmetry in the older group. Further analysis suggested that a significant decline in dominant (right) hand function resulted in less asymmetric performance in older adults. The finding is inconsistent with the application of the HAROLD model in the motor domain, which assumes improved performance in the non-dominant hand, leading to a reduction of motor asymmetry in older adults. Based on the manual performance in young and older adults, it is suggested that aging reduces manual asymmetry in both force production and manual dexterity due to the reduced performance of the dominant hand.

Kinematic evaluation and reliability assessment of the Nine Hole Peg Test for manual dexterity.

BACKGROUND: The Nine Hole Peg Test (NHPT) is one of the most frequently used tools to assess manual dexterity. However, no kinematic parameters are provided to describe the quality of the motor performance, since time is the only score. PURPOSE: To investigate test-retest and intra-rater reliability, correlation with clinical test score, and discriminant validity of kinematic indexes during NHPT. STUDY DESIGN: A clinical measurement study. METHODS: Twenty-five healthy right-handed volunteers performed the NHPT. An experienced physiotherapist administered two sessions at a 6-hour interval with two trials for dominant and non-dominant upper limbs. An optoelectronic system was used to detect NHPT performance, which was divided into nine consecutive peg-grasp, peg-transfer, peg-in-hole, hand-return phases, and one final removing phase. Outcome measures were total and single phases times, normalized jerk, mean, peak and time-to-peak of velocity, curvature index during peg-grasp and hand-return phases, and trunk 3D displacement. The statistical analysis included Intraclass Correlation Coefficients (ICCs) for test-retest and intra-rater reliability, Pearson's coefficients for correlation with the NHPT score, and paired t-tests for discriminant validity. RESULTS: Test-retest reliability was excellent for trunk rotation (ICC: 0.91) and good to moderate for the other indexes (ICCs: 0.89-0.61). Intra-rater reliability was excellent for total and removing times (ICCs: 0.91 and 0.94) and good to moderate for the other indexes (ICCs: 0.84-0.66), except for trunk inclination (ICC: 0.37). NHPT phases, normalized jerk, mean velocity, peak of velocity, time-to-peak and curvature index correlated with total time (r-score: 0.8-0.3). NHPT phases and most kinematic indexes discriminated the dominant from non-dominant upper limb, with the greatest effect size for normalized jerk during hand-return (d = 1.16). CONCLUSIONS: Kinematic indexes during NHPT can be considered for manual dexterity assessment. These indexes may allow for the detection of kinematic changes responsible for NHPT score variations in healthy subjects or patients with upper limb impairments.

Determinants of hand function in children and adolescent with Down Syndrome-A scoping review.

BACKGROUND: Down Syndrome (DS) is a genetic condition. Physical characteristics like short stature, hypotonia, small, and thick hands result in decreased grip and pinch strength and quality of fine motor tasks. PURPOSE: The purpose of this review is to summarize the evidence of upper extremity physical characteristics and its influence on hand function in DS population. STUDY DESIGN: A scoping review. METHODOLOGY: A comprehensive electronic literature search was conducted through PubMed, CINAHL, Cochrane Library. The search was limited to articles written in English and published between 2010 to 2021. Additionally, books were referred for a better understanding of the hand function in DS. The Preferred Reporting Items for Systematic Review and Meta-Analysis extension for scoping reviews (PRISMA-ScR) was adopted to develop the protocol. RESULTS: Following a detailed review of 28 articles meeting the inclusion criteria, fetuses with a diagnosis of DS are reported to have shortening of humerus on sonographic markers wherein 9% of fetuses had below 5th percentile shortening. Additionally, literature reports that during reaching there was increased trunk rotation (effect size = 0.88). DS population had 60% less grip strength, 33% less palmar pinch strength ,20% less key pinch strength and poor manual dexterity (CI = 4.5-5.5). CONCLUSION: Findings of this review concludes that physical characteristics of the upper extremity have an influence on hand function performance in children and adolescents with DS.However, only arm length and hand span have been quantified and correlated with grip strength. Further work must focus on correlation of upper extremity anthropometry and overall hand function in children and adolscents with DS.

Preclinical dental training: Association between fine motor skills and compliance with ergonomic posture techniques.

OBJECTIVE: The aim of this study was to evaluate the dental students' fine motor skills and their compliance with ergonomic posture techniques over the course of a preclinical training year. The correlation between fine motor skills and compliance was also assessed. METHODS: The ergonomic posture of students enrolled in the second year of a five-year undergraduate dental degree programme (n = 62) was assessed using the Compliance Assessment of Dental Ergonomic Posture Requirements (CADEP). This assessment relied on photographs of the students performing preclinical laboratory procedures during the school year. The photographs of each procedure received a score, and the final score obtained (0 to 10) corresponded to the extent of the student's compliance with ergonomic posture techniques. Initial compliance was calculated during the first two months of the training programme, whilst final compliance was calculated during the last two months. Fine motor skills were evaluated using the modified Dental Manual Dexterity Assessment (DMDA), which was also applied at the beginning and the end of the school year. Data were assessed statistically by Student's paired t test, and the correlation between fine motor skills and compliance with ergonomic posture techniques was estimated by Pearson's correlation coefficient (r) and Student's t test (α = 0.05). RESULTS: The compliance scores were higher at the end of the academic year than at the beginning of year (p < 0.001; t = -5.300). Fine motor skills improved significantly with time (p < 0.001; t = -10.975). Non-significant correlations were found between students' fine motor skills and their economic posture compliance both at the beginning (r = -0.197; p = 0.126) and at the end of the training year (r = 0.226; p = 0.078). CONCLUSION: The students' manual dexterity and compliance with ergonomic posture techniques increased over the course of the preclinical training year, and the correlation between students' fine motor skills and their ergonomic posture compliance was not significant.