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* Problem Statement: Soccer players expose themselves to repetitive head impacts (RHI) by purposefully heading the ball - an act that has been suggested to adversely affect brain structure and function and potentially contribute to the long-term development of neurodegenerative disorders. A deeper understanding of the head's kinematic response to these RHI is crucial to assess the actual risk resulting from routine soccer heading. To that aim, we investigated the influence of a comprehensive set of heading-related factors on the resulting linear and rotational acceleration of the head, as obtained by wearable sensors in a field study. * Methods: Across 26 matches, 19 semi-professional female soccer players (23.0±3.7 years) were equipped with wearable head impact sensors that registered peak linear acceleration (PLA) and peak rotational acceleration (PRA) of on-field head impact events. Actual headers were confirmed and further allocated to the following categories using video analyses: Scenario, Distance, Player Movement, Ball Reflection, Impact Location, Duel, Jump. Linear mixed models were used to assess the relationships between these factors and PLA as well as PRA. * Results: Average PLA and PRA of the head due to heading was 29.6 (±18.1) g and 6195.6 (±4448.1) rad/s², respectively. Analyses revealed a statistically significant influence of three factors on both PLA (R2=0.34) and PRA (R2=0.37). Next to subject-related factors (p<0.001; proportional variance: 12.6% [PLA] and 19.0% [PRA]), especially longer in-air distances of the ball prior to heading (p<0.001; proportional variance: 24.6% [PLA] and 19.2% [PRA]) as well as a greater extent of ball reflection due to a header (p<0.001; proportional variance: 9.2% [PLA] and 6.9% [PRA]) were significantly associated with increases in head impact kinematics. * Conclusion: Our findings demonstrate that the ball's travelling distance and the extent of ball reflection due to a header directly affect the head's kinematic response to purposeful headers in female players. Along with these factors, future studies should focus on the direct assessment of inter-individual differences in heading technique and anthropometric variables to increase the current understanding of the potential risk resulting from RHI due to soccer heading. [ABSTRACT FROM AUTHOR]

Background/Objectives: Evidence regarding the effect of n-3 long-chain polyunsaturated fatty acid (LCPUFA) supplementation during pregnancy on offspring's neurodevelopment is not conclusive. Subjects/Methods: In this analysis, the effect of a reduced n-6:n-3 LCPUFA ratio in the diet of pregnant/lactating women (1.2 g n-3 LCPUFA together with an arachidonic acid (AA)-balanced diet between 15th wk of gestation-4 months postpartum vs control diet) on child neurodevelopment at 4 and 5 years of age was assessed. A child development inventory (CDI) questionnaire and a hand movement test measuring mirror movements (MMs) were applied and the association with cord blood LCPUFA concentrations examined. Results: CDI questionnaire data, which categorizes children as 'normal', 'borderline' or 'delayed' in different areas of development, showed no significant evidence between study groups at 4 (n=119) and 5 years (n=130) except for the area 'letters' at 5 years of age (P=0.043). Similarly, the results did not strongly support the hypothesis that the intervention has a beneficial effect on MMs (for example, at 5 years: dominant hand, fast: adjusted mean difference, -0.08 (-0.43, 0.26); P=0.631). Children exposed to higher cord blood concentrations of docosahexaenoic acid, eicosapentaenoic acid and AA, as well as a lower ratio of n-6:n-3 fatty acids appeared to show beneficial effects on MMs, but these results were largely not statistically significant. Conclusions: Our results do not show clear benefits or harms of a change in the n-6:n-3 LCPUFA ratio during pregnancy on offspring's neurodevelopment at preschool age. Findings on cord blood LCPUFAs point to a potential influence on offspring development., Author(s): C Brei [sup.1] , L Stecher [sup.1] , S Brunner [sup.1] , R Ensenauer [sup.2] [sup.3] , F Heinen [sup.4] , P D Wagner [sup.5] , J Hermsdörfer [sup.5] [...]

Co-activation of both hemispheres seems to play a critical role in the generation of mirror movements, involuntary muscle contractions opposite to voluntary movements of one hand. The relationship between handedness and mirror movements is unclear. We measured repetitive grip force changes performed at slow and fast frequencies with the active hand and recorded mirror activity in the opposite inactive hand in 17 healthy left-handed (LH) and 17 right-handed (RH) participants. Data suggest significant differences between RH and LH with respect to the temporo-spatial characteristics of mirror activity, but not in general mirror movement strength. Mirror activity correlation was more pronounced when the non-dominant hand was active in RH, while LH did not show such an asymmetry. We suggest that the dependence of mirror activity on the active hand in right-handers but not in left-handers reflects the more general finding of stronger manual asymmetry in brain activation as well as in functional performance in right-handers. [ABSTRACT FROM AUTHOR]

The influence of the cerebellum on independent finger control has rarely been investigated. We examined multidigit control in 22 patients with cerebellar degeneration, 20 patients with cerebellar stroke, and 21 patients with surgical lesions after cerebellar tumor removal. In the first task, either the index finger or the middle finger was actively lifted from an object during static holding. Both controls and cerebellar patients increased the forces of the nearby digits in synchrony with lift-off to maintain the total finger force. Patients used increased finger forces but showed no significant deficits in the pattern and timing of rearrangement of finger forces. In the second task, subjects had to press and release one finger against a force-sensitive keypad with the other fingers being inactive. All patient groups showed increased force production of the noninstructed (enslaved) fingers compared with controls. Lesionsymptom mapping in the focal patients revealed that lesions of the superior hand area were related to abnormal levels of enslaving. Increased finger forces in the finger-lifting task likely reflect an unspecific safety strategy. Increased effects of enslaving in the individuated key-press task, however, may be explained by a deterioration of cerebellar contribution to feedforward commands necessary to suppress activity in noninstructed fingers or by increased spread of the motor command intended for the instructed finger. Despite the large and diverse patient sample, surprisingly few abnormalities were observed. Both holding an object and finger typing are overlearned, automatized motor tasks, which may not or little depend on the integrity of the cerebellum. [ABSTRACT FROM AUTHOR]

Abstract: In a recent study using voxel based lesion symptom mapping (VLSM) in cerebellar patients following stroke we found associations of prehensile deficits to lesions of the cerebellar cortex and dentate nucleus (DN). Associations to lesions of the interposed nucleus (IN), which has been shown to contribute to prehension in monkeys, could not be established. One possible reason was that the IN was largely unaffected in the stroke patients. To further address the question of IN involvement in prehension we performed VLSM in patients with surgical cerebellar lesions (n =20), exhibiting high lesion overlap in the medial and intermediate cerebellum including the IN. Prehensile deficits were quantified by analyses of movement kinematics and finger forces. In the patient population prehensile deficits comprised lower movement velocity in reaching and increased lift-off time in grasping. These were associated with lesions of the intermediate and lateral cerebellar cortex together with their output nuclei. Specifically, IN lesions were linked to increased lift-off time in grasping and not to slower reaching movements. Thus, our data support IN contribution particularly for the fluent production of grip forces during dexterous prehension in humans. [Copyright &y& Elsevier]

Abstract: Objective: Limited resources in terms of elementary functions may be a limiting factor for functional activities. The objective of the study was to examine basic hand motor capacities in young children with bilateral spastic cerebral palsy (BSCP) and to compare with deficits in functional activities. Method: Eighty-eight children with BSCP, 3–6 years of age, manipulated a grip object (200g) equipped with a uniaxial force sensor. Basic motor capacity was assessed based upon (1) maximal grip strength and (2) production of fast repetitive grip force changes (FFC) while holding the object on the table. Subjects’ performance on this task was compared to the grip force amplitude and force rate assessed while the subject was lifting the same object. Results were compared between different degrees of manual ability according to the Manual Ability Classification System (MACS). Results: In children with BSCP, even in high-functioning children with MACS 1, fast grip force changes and grip strength were 2 SDs and more below the mean of controls. Differences increased from MACS 2 to 4 but not between MACS 1 and 2. During lifting children with BSCP used considerable proportions of their maximum grip strength (40–90%) and of their grip force rates during 70% vs. 86%. In some children with low manual abilities (MACS 3/4), grip force rates during lifting were higher than during FFC. Conclusion: In children with BSCP, basic motor capacity may influence manual ability, particularly in children with MACS 3 and 4. In some of these children, the underlying processes during lifting may also differ qualitatively. [Copyright &y& Elsevier]

Background. Although feed-forward mechanisms of grip force control are a prerequisite for skilled object manipulation, somatosensory feedback is essential to acquire, maintain, and adapt these mechanisms. Objective. Individuals with complete peripheral deafferentation provide the unique opportunity to study the function of the motor system deprived of somatosensory feedback. Methods. Two individuals (GL and IW) with complete chronic deafferentation of the trunk and limbs were tested during cyclic vertical movements of a handheld object. Such movements induce oscillating loads that are typically anticipated by parallel modulations of the grip force. Load magnitude was altered by varying either the movement frequency or object weight. Results. GL and IW employed excessive grip forces probably reflecting a compensatory mechanism. Despite this overall force increase, both deafferented participants adjusted their grip force level according to the load magnitude, indicating preserved scaling of the background grip force to physical demands. The dynamic modulation of the grip force with the load force was largely absent in GL, whereas in IW only slower movements were clearly affected. Conclusions. The authors hypothesize that the deafferented patients may have utilized visual and vestibular cues and/or an efferent copy of the motor command of the arm movement to scale the grip force level. Severely impaired grip force-load coupling in GL suggests that sensory information is important for maintaining a precise internal model of dynamic grip force control. However, comparably better performance in IW argues for the possibility that alternative cues can be used to trigger a residual internal model. [ABSTRACT FROM AUTHOR]

A commonly experienced effect of cold is a sensation of numbness and loss of sensibility in the fingers. Intact tactile sensibility of the grasping digits is essential for the efficient scaling of grip force level during the manipulation of hand-held objects. We investigated whether or not cooling of the grasping digits affects scaling of the grip force magnitude in relation to the loads resulting from continuous vertical arm movements performed with a grasped instrumented object. Maxima and minima of load force occurred at the lower and upper turning point of the movement cycle, respectively, and were accompanied by maximum and minimum peaks in grip force occurring close in time prior to and following digit cooling, respectively. Thus, digit cooling did not influence the ability to adjust the grip force profile in anticipation of movement-induced fluctuations in load force. However, subjects established significantly higher grip forces against the hand-held object following digit cooling and generated a 10-70% higher ratio between grip and load forces at the upper and lower turning points of the movement cycle. It is thought that the impaired economical scaling of grip force level is the result of reduced sensory feedback from the grasping fingers during digit cooling. The results provide further evidence to support the suggestion that cutaneous afferent input plays a subordinate role in the predictive temporal regulation of the grip force profile, but is used to adapt economically the force level to the actual loading requirements during dynamic object manipulation. [ABSTRACT FROM AUTHOR]

• The WSS can predict the EDSS with an R² adjusted of 0.81 • MS patients improved by 0.21 WSS points in average during 17d of rehabilitation • Main contributing factor was gait quality • The improvement during rehabilitation could not be predicted Multiple sclerosis is an autoimmune disease with a plethora of potentially arising impairments and a coarse standard clinical estimation of severity, the expanded disability status scale (EDSS). In this study, we introduced the Watzmann Severity Scale (WSS), a sensorimotor function based statistical model of the EDSS of 113 patients. Using the WSS, we examined the rehabilitation course of 87 patients. The WSS revealed to be a reliable estimate of the EDSS with an R² adjusted of 0.81, although lower EDSS grades were systematically overestimated. Further, patients slightly improved during their inpatient stay of in average 17d by 0.21 on the WSS, with changes in gait performance being the driving factor (|β|-weight of 0.84). We were not able to reliably predict changes in the WSS and found no association with the duration of hospitalization. We conclude and advise that rehabilitation should start earlier, if lower EDSS grades were not overestimated, to emphasize gait less in rehabilitation, and to change from a perspective of impairment and disability to performance in order to maximize patient rehabilitation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Writer’s cramp increased grip force to hold the pen during handwriting but not to lift and move objects. [•] Patients with writer’s cramp did not generalize grip force levels across manipulation tasks. [•] Grip force regulation during handwriting in writer’s cramp is task-specific and individualised. [Copyright &y& Elsevier]

Abstract: While high-resolution structural magnetic resonance imaging (MRI) combined with newer analysis methods has become a powerful tool in human cerebral lesion studies, comparatively few studies have used these advanced imaging techniques to study lesions of the human cerebellum and their associated symptoms. This review will summarize the methodology of MRI-based lesion-symptom mapping of the human cerebellum and discuss its potential for gaining insights into cerebellar function. The investigation of patients with defined focal lesions yields the greatest potential for obtaining meaningful correlations between lesion site and behavioral deficits. In smaller groups of patients overlay plots and subtraction analysis are good options. If larger groups of patients are available, different statistical techniques have been introduced to compare behavior and lesion site on a voxel-by-voxel basis. Although localization in degenerative cerebellar disorders is less accurate because of the diffuse nature of the disease, certain information about the supposed function of larger subdivisions of the cerebellum can be gained. Examples are given which show that lesion-symptom mapping allows to investigate the function of the intermediate zone and cerebellar nuclei. We conclude that meaningful correlations between lesion site and behavioral data can be obtained in patients with degenerative as well as focal cerebellar disorders. [Copyright &y& Elsevier]

Not applicable., (© 2024. The Author(s).)

Objective: To determine whether dual-task interference during upper limb tasks is increased in patients after stroke compared to healthy older subjects and to compare magnitude of stroke-induced change in interference to that explained by aging., Methods: We conducted a systematic literature search in MEDLINE, CINAHL, Google Scholar and PEDro databases up to October 2023 for studies on upper limb dual-tasks in stroke and elderly healthy subjects. Eleven upper limb dual-task studies in stroke patients and 11 studies in healthy older subjects were identified and systematically reviewed. A meta-analysis was performed on seven stroke studies and on five studies in healthy older subjects that included control groups., Results: Most stroke studies investigated proximal arm movements with kinematic measures, but few studies evaluated manual dexterity. In contrast, studies in healthy older subjects used more distal (finger tapping) tasks. The meta-analysis showed that stroke patients had on average a 19% (CI 95% = 1.0-37.3) increase in dual-task interference compared to age-matched healthy controls ( Z  = 2.06, p  = 0.04). Older healthy subjects showed greater dual-task interference compared to younger subjects (19% greater, CI 95% = 6.5-31.2, Z  = 2.98, p  = 0.003)., Conclusion: Meta-analysis revealed an increase in dual-task interference during upper limb movements in stroke patients, exceeding age-related changes, supporting the presence of subclinical impairments in divided attention post-stroke that may impede motor recovery., Competing Interests: MAM and PGL have patented the method for multidimensional measurement of manual dexterity (WO2016184935A3). PL is a founding member of Dextrain company commercializing innovation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Lindberg, AmirShemiraniha, Krewer, Maier and Hermsdörfer.)

Background: After standard care, 55%-75% of patients after stroke show a persistent paresis of the upper limb (UL). Assistive devices are developed to increase the patients' level of independence in daily life., Objectives: To investigate the potential of Functional Electrical Stimulation (FES) to assist object manipulation in activities of daily life., Design: Seventeen patients after stroke were tested and analyzed in a randomized cross-over design., Methods: Functional grasping was assessed by means of the Action Research Arm Test (ARAT) and the modified Box and Block Test (mBBT), in one session with and another without FES assistance. The order of sessions was randomized. Patients' motivation was assessed after each session. Task performance and motivation were compared between conditions using the Wilcoxon test and subgroup analyses were performed for impairment severity by distribution-based mixed-factor analyses., Results: When analyzing the total ARAT, FES did not effectively assist the overall performance ( P = .142), but did assist the performance of objects of the Grasp category ( P = .020). Impairment severity showed an interaction with the orthotic effect ( P = .012), as severely impaired patients profited from FES assistance and mild-moderately impaired did not. When focusing on the more functional items of the ARAT (i.e., excluding scores from thumb-middle and thumb-ring finger combinations), there was a significant orthotic effect of FES on task performance ( P = .023). Further, there was an orthotic effect for the number of transported blocks in the mBBT ( P = .033), exclusively prominent in the group of severely impaired patients. Functional Electrical Stimulation did not increase the patients' motivation ( P = .959), which was high after both conditions., Conclusion: Functional Electrical Stimulation has the potential to support object manipulation, but is dependent on impairment severity and object type. To observe a consistent orthotic effect, features of the stimulator should be further developed to generate appropriate grasps and forces across subjects and objects., Trial Registration: The trial was registered with the German Clinical Trials Register (DRKS00025889)., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2024.)