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"Brown, Susan H"
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Reduced Facilitation of Parietal-Motor Functional Connections in Older Adults
Age-related changes in cortico-cortical connectivity in the human motor network in older adults are associated with declines in hand dexterity. Posterior parietal cortex (PPC) is strongly interconnected with motor areas and plays a critical role in many aspects of motor planning. Functional connectivity measures derived from dual-site transcranial magnetic stimulation (dsTMS) studies have found facilitatory inputs from PPC to ipsilateral primary motor cortex (M1) in younger adults. In this study, we investigated whether facilitatory inputs from PPC to M1 are altered by age. We used dsTMS in a conditioning-test paradigm to characterize patterns of functional connectivity between the left PPC and ipsilateral M1 and a standard pegboard test to assess skilled hand motor function in 13 young and 13 older adults. We found a PPC-M1 facilitation in young adults but not older adults. Older adults also showed a decline in motor performance compared to young adults. We conclude that the reduced PPC-M1 facilitation in older adults may be an early marker of age-related decline in the neural control of movement.
Journal Article
Home-based movement therapy in neonatal brachial plexus palsy: A case study
Case report.
The value of movement-based therapy in peripheral nerve injury conditions such as neonatal brachial plexus palsy (NBPP) is unclear.
To determine the effectiveness of a home-based movement therapy program in a 17 year old female patient with a right NBPP pan-plexopathy.
Home training consisted of arm reaching and object manipulation tasks using devices which recorded performance. Training occurred for 1 h/day, 5 days/week for 6 weeks with periodic webcam supervision. Pre- and post clinical, functional and kinematic assessments were performed in a laboratory setting.
Following training, shoulder flexion and elbow extension active range of motion increased by 13° and 9°, respectively, and functional ability also improved. Reach movement duration decreased significantly with a concomitant improvement in movement coordination.
These results demonstrate that movement therapy has the potential to improve motor function in NBPP years after the initial insult.
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Journal Article
Effectiveness of a home training program on improving pinch force perception in older adults
Hand function is reduced with aging which can lead to impairments in the performance of daily activities and eventually loss of independence. The ability to perceive the forces being applied to an object is an important component of hand control that also declines with age. However, the extent to which force perception can be improved through training remains largely unknown.
This study evaluated the effectiveness of a home-training program focused on improving force perception in older adults.
Quasi-experimental - Uncontrolled trial.
Eleven independent, healthy adults (mean age: 77.2 ± 6.8 years) participated in a home-based sensorimotor hand training program 6 days/week for 6 weeks. Force perception, the primary outcome variable, was measured as the ability to reproduce a pinch force equal to 25% maximum voluntary contraction in the absence of visual feedback using either the ipsilateral remembered or contralateral concurrent (CC) hand. We also measured hand strength, dexterity, tactile acuity, and cognition before and after training.
After the program was completed, participants showed a 35% reduction in absolute (p < 0.01, confidence interval (CI): [7.3, 33.2], effect sizes (ES): 0.87) and constant (p = 0.05, CI: [0.0, 34.9], ES: 0.79) force matching errors in the CC condition. Improvements in dominant hand dexterity (Purdue pegboard test) (p < 0.05, CI: [0.2, 2.4], ES: 0.60) and tactile sensitivity (JVP thresholds) (p < 0.05, CI: [−1.7, −0.1], ES: 0.94), as well as cognition (Trail Making Test B) (p < 0.05, CI: [−24,1. −1.6], ES: 0.30) were also observed post-training.
The results suggest that home-hand training can be an effective way to improve force perception among older adults.
•Fine hand force perception can be improved with task-based training in older adults.•Improvements in force perception can occur after 6 weeks of home-based training.•Dexterity, tactile acuity, and cognitive function also improved following training.
Journal Article
Quantifying Real-World Upper-Limb Activity Via Patient-Initiated Movement After Nerve Reconstruction for Upper Brachial Plexus Injury
BACKGROUND:A critical concept in brachial plexus reconstruction is the accurate assessment of functional outcomes. The current standard for motor outcome assessment is clinician-elicited, outpatient clinic-based, serial evaluation of range of motion and muscle power. However, discrepancies exist between such clinical measurements and actual patient-initiated use. We employed emerging technology in the form of accelerometry-based motion detectors to quantify real-world arm use after brachial plexus surgery.
OBJECTIVE:To evaluate (1) the ability of accelerometry-based motion detectors to assess functional outcome and (2) the real-world arm use of patients after nerve transfer for brachial plexus injury, through a pilot study.
METHODS:Five male patients who underwent nerve transfer after brachial plexus injury wore bilateral motion detectors for 7 d. The patients also underwent range-of-motion evaluation and completed multiple patient-reported outcome surveys.
RESULTS:The average age of the recruits was 41 yr (±17 yr), and the average time from operation was 2 yr (±1 yr). The VT (time of use ratio) for the affected side compared to the unaffected side was 0.73 (±0.27), and the VM (magnitude ratio) was 0.63 (±0.59). VT strongly and positively correlated with shoulder flexion and shoulder abduction0.97 (P = .008) and 0.99 (P = .002), respectively.
CONCLUSION:Accelerometry-based activity monitors can successfully assess real-world functional outcomes after brachial plexus reconstruction. This pilot study demonstrates that patients after nerve transfer are utilizing their affected limbs significantly in daily activities and that recovery of shoulder function is critical.
Journal Article
Use of a Novel Theory-Based Pragmatic Tool to Evaluate the Quality of Instructor-Led Exercise Videos to Promote Youth Physical Activity at Home: Preliminary Findings
Background: Exercise videos that work to minimize cognitive load (the amount of information that working memory can hold at one time) are hypothesized to be more engaging, leading to increased PA participation. Purpose: To use a theory-based pragmatic tool to evaluate the cognitive load of instructor-led exercise videos associated with the Interrupting Prolonged Sitting with ACTivity (InPACT) program. Methods: Exercise videos were created by physical education teachers and fitness professionals. An evaluation rubric was created to identify elements each video must contain to reduce cognitive load, which included three domains with four components each [technical (visual quality, audio quality, matching modality, signaling), content (instructional objective, met objective, call-to-action, bias), and instructional (learner engagement, content organization, segmenting, weeding)]. Each category was scored on a 3-point scale from 0 (absent) to 2 (proficient). A video scoring 20–24 points induced low cognitive load, 13–19 points induced moderate cognitive load, and less than 13 points induced high cognitive load. Three reviewers independently evaluated the videos and then agreed on scores and feedback. Results: All 132 videos were evaluated. Mean video total score was 20.1 ± 0.7 points out of 24. Eighty-five percent of videos were rated low cognitive load, 15% were rated moderate cognitive load, and 0% were rated high cognitive load. The following components scored the highest: audio quality and matching modality. The following components scored the lowest: signaling and call-to-action. Conclusions: Understanding the use of a pragmatic tool is a first step in the evaluation of InPACT at Home exercise videos. Our preliminary findings suggest that the InPACT at Home videos had low cognitive load. If future research confirms our findings, using a more rigorous study design, then developing a collection of instructor-led exercise videos that induce low cognitive load may help to enhance youth physical activity participation in the home environment.
Journal Article
Is maximum grip strength a reliable predictor of hand limitations among older adults?
BackgroundGrip strength is commonly used to assess hand function among older adults. While shown to be associated with disability, the degree to which grip strength specifically predicts hand limitations is unknown.AimsThe primary aim of this study was to evaluate grip strength as a predictor of hand limitations.MethodsUsing the 2011–14 National Health and Nutrition Examination Survey (NHANES), we classified older adults reporting one or more hand limitations versus those with no limitations. Odds ratios were used to assess the association between grip strength (separated into quartiles) and the likelihood of a hand limitation while controlling for sex, race/ethnicity, education level, income, and pain. Receiver operator characteristic (ROC) curves were used to evaluate the degree to which grip strength discriminates between older adults with and without a hand limitation.ResultsWe identified 2064 older adults (age ≥ 65), 31% of whom reported a hand-related limitation. Older adults with very low grip strength (weakest quartile) were more likely to report at least one limitation (OR: 6.1, 95% CI: 3.2, 11.8) than those with high grip strength (strongest quartile). However, grip strength had poor to moderate discrimination of hand limitations (ROC area under curves: 0.65–0.81).DiscussionWhile self-reported hand limitations were associated with lower grip strength; overall, it is a relatively poor predictor of hand impairments among older adults.ConclusionBetter assessments are needed to adequately evaluate upper extremity impairments to help older adults maintain functional independence.
Journal Article
Task-dependent asymmetries in the utilization of proprioceptive feedback for goal-directed movement
Whereas the majority of studies regarding upper limb asymmetries in motor performance have focused on preferred arm dominance for producing motor output, studies exploring the role of sensory feedback have suggested that the preferred and non-preferred arms are specialized for different aspects of movement. A recent study by Goble et al. (2006) found evidence of a non-preferred left arm (and presumably right hemisphere) proprioceptive dominance for a target matching task that required subjects to both memorize and transfer across hemispheres proprioceptive target information. This paradigm contrasted previous studies of proprioceptive matching asymmetry that explored only memory-based matching and produced equivocal results. The purpose of the present study, therefore, was to examine task-dependent asymmetries in proprioceptive matching performance, including differences related to active versus passive presentation of the matching target. It was found that the non-preferred left arm of right handers matched target elbow angles more accurately than the preferred arm, but only in the matching condition that required both memory and interhemispheric transfer. Task-dependent asymmetries were not affected by the mode of target presentation and assessment of matching kinematics revealed differences in strategy for both the speed and smoothness of targeted movements. Taken together, these results suggest that the non-preferred arm/hemisphere system is specialized for the processing of movement-related proprioceptive feedback.
Journal Article
Compromised encoding of proprioceptively determined joint angles in older adults: the role of working memory and attentional load
Perceiving the positions and movements of one’s body segments (i.e., proprioception) is critical for movement control. However, this ability declines with older age as has been demonstrated by joint angle matching paradigms in the absence of vision. The aim of the present study was to explore the extent to which reduced working memory and attentional load influence older adult proprioceptive matching performance. Older adults with relatively HIGH versus LOW working memory ability as determined by backward digit span and healthy younger adults, performed memory-based elbow position matching with and without attentional load (i.e., counting by 3 s) during target position encoding. Even without attentional load, older adults with LOW digit spans (i.e., 4 digits or less) had larger matching errors than younger adults. Further, LOW older adults made significantly greater errors when attentional loads were present during proprioceptive target encoding as compared to both younger and older adults with HIGH digit span scores (i.e., 5 digits or greater). These results extend previous position matching results that suggested greater errors in older adults were due to degraded input signals from peripheral mechanoreceptors. Specifically, the present work highlights the role cognitive factors play in the assessment of older adult proprioceptive acuity using memory-based matching paradigms. Older adults with LOW working memory appear prone to compromised proprioceptive encoding, especially when secondary cognitive tasks must be concurrently executed. This may ultimately result in poorer performance on various activities of daily living.
Journal Article