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The Performance Index (P-Index) is a measure for evaluating mobility-related dual-task performance in older adults. The identification of specific clinicodemographic factors predictive of P-Index scores, however, remains unclear. This cross-sectional study analyzed data from 120 community-dwelling older adults (average age 71.3 ± 11.23 years) to explore clinicodemographic variables that influence P-Index scores during the instrumented timed up and go test. Unadjusted analyses suggested several factors, including age, gender, body mass index, Mini-Mental Status Examination scores, functional reach test performance, history of falls, ethnicity, Geriatric Depression Scale scores, alcohol consumption, and educational levels, as potential predictors of P-Index. However, adjusted multinomial multiple regression analysis revealed Geriatric Depression Scale and Mini-Mental Status Examination scores as the exclusive independent predictors of P-Index classifications, segmented into high, intermediate, or low (percentiles ≤ 25, 26–74, or ≥ 75, respectively). A significant association was observed between the manifestation of depressive symptoms, lower Mini-Mental Status Examination scores, and reduced cognitive–motor performance. The findings implicate depressive symptoms and low cognitive performance as substantial impediments to optimal dual-task mobility within this cohort. Further studies are warranted to examine the efficacy of cognitive stimulation and antidepressant therapy, in augmenting mobility-related dual-task performance among older adults. [ABSTRACT FROM AUTHOR]

Key points The central and peripheral nervous systems are specialized to conduct electrical currents that underlie behaviour. When this multidimensional electrical system is disrupted by degeneration, damage, or disuse, externally applied electrical currents may act to modulate neural structures and provide therapeutic benefit. The administration of electrical stimulation can exert precise and multi‐faceted effects at cellular, circuit and systems levels to restore or enhance the functionality of the central nervous system by providing an access route to target specific cells, fibres of passage, neurotransmitter systems, and/or afferent/efferent communication to enable positive changes in behaviour. Here we examine the neural mechanisms that are thought to underlie the therapeutic effects seen with current neuromodulation technologies. To gain further insights into the mechanisms associated with electrical stimulation, we summarize recent findings from genetic dissection studies conducted in animal models. Electricity is everywhere around us and is essential for how our nerves communicate within our bodies. When nerves are damaged or not working properly, using exogenous electricity can help improve their function at distinct levels – inside individual cells, within neural circuits, and across entire systems. This method can be tailored to target specific types of cells, nerve fibres, neurotransmitters and communication pathways, offering significant therapeutic potential. This overview explains how exogenous electricity affects nerve function and its potential benefits, based on research in animal studies. Understanding these effects is important because electrical neuromodulation plays a key role in medical treatments for neurological conditions. [ABSTRACT FROM AUTHOR]

Disruptions in the brain's connections to the hands resulting from a cervical spinal cord injury (cSCI) can lead to severe and persistent functional impairments. The integrity of these connections is an important predictor of upper extremity recovery in stroke and may similarly act as a biomarker in cSCI. In this perspective article, we review recent findings from a large cohort of individuals with cSCI, demonstrating the predictive value of corticospinal tract (CST) integrity in cSCI—CST sparing. This research underscores that, akin to stroke, the integrity of brain-to-hand connections is crucial for predicting upper extremity recovery following cSCI. We address the limitations of commonly used metrics, such as sacral sparing and the concept of central cord syndrome. Furthermore, we offer insights on emerging metrics, such as tissue bridges, emphasizing their potential in assessing the integrity of brain connections to the spinal cord. [ABSTRACT FROM AUTHOR]

Introduction: Transcutaneous spinal cord stimulation (TSCS), a non-invasive form of spinal cord stimulation, has been shown to improve motor function in individuals living with spinal cord injury (SCI). However, the effects of different types of TSCS currents including direct current (DC-TSCS), alternating current (AC-TSCS), and spinal paired stimulation on the excitability of neural pathways have not been systematically investigated. The objective of this systematic review was to determine the effects of TSCS on the excitability of neural pathways in adults with non-progressive SCI at any level. Methods: The following databases were searched from their inception until June 2022: MEDLINE ALL, Embase, Web of Science, Cochrane Library, and clinical trials. A total of 4,431 abstracts were screened, and 23 articles were included. Results: Nineteen studies used TSCS at the thoracolumbar enlargement for lower limb rehabilitation (gait & balance) and four studies used cervical TSCS for upper limb rehabilitation. Sixteen studies measured spinal excitability by reporting different outcomes including Hoffmann reflex (H-reflex), flexion reflex excitability, spinal motor evoked potentials (SMEPs), cervicomedullay evoked potentials (CMEPs), and cutaneous-input-evoked muscle response. Seven studies measured corticospinal excitability using motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS), and one study measured somatosensory evoked potentials (SSEPs) following TSCS. Our findings indicated a decrease in the amplitude of H-reflex and long latency flexion reflex following AC-TSCS, alongside an increase in the amplitudes of SMEPs and CMEPs. Moreover, the application of the TSCS-TMS paired associative technique resulted in spinal reflex inhibition, manifested by reduced amplitudes in both the H-reflex and flexion reflex arc. In terms of corticospinal excitability, findings from 5 studies demonstrated an increase in the amplitude of MEPs linked to lower limb muscles following DC-TSCS, in addition to paired associative stimulation involving repetitive TMS on the brain and DC-TSCS on the spine. There was an observed improvement in the latency of SSEPs in a single study. Notably, the overall quality of evidence, assessed by the modified Downs and Black Quality assessment, was deemed poor. Discussion: This review unveils the systematic evidence supporting the potential of TSCS in reshaping both spinal and supraspinal neuronal circuitries post-SCI. Yet, it underscores the critical necessity for more rigorous, high-quality investigations. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) is a profoundly debilitating condition with no effective treatment to date. The complex response of the central nervous system (CNS) to injury and its limited regeneration capacity pose bold challenges for restoring function. Cervical SCIs are the most prevalent and regaining hand function is a top priority for individuals living with cervical SCI. A promising avenue for addressing this challenge arises from the emerging field of regenerative rehabilitation, which combines regenerative biology with physical medicine approaches. The hypothesis for optimizing gains in upper extremity function centers on the integration of targeted neurorehabilitation with novel cell- and stem cell-based therapies. However, the precise roles and synergistic effects of these components remain poorly understood, given the intricate nature of SCI and the diversity of regenerative approaches. This perspective article sheds light on the current state of regenerative rehabilitation for cervical SCI. Notably, preclinical research has yet to fully incorporate rehabilitation protocols that mimic current clinical practices, which often rely on neuromodulation strategies to activate spared circuits below the injury level. Therefore, it becomes imperative to comprehensively investigate the combined effects of neuromodulation and regenerative medicine strategies in animal models before translating these therapies to individuals with SCI. In cases of severe upper extremity paralysis, the advent of neuromodulation strategies, such as corticospinal tract (CST) and spinal cord stimulation, holds promise as the next frontier in enhancing the effectiveness of cell- and stem cell-based therapies. Future preclinical studies should explore this convergence of neuromodulation and regenerative approaches to unlock new possibilities for upper extremity treatment after SCI. [ABSTRACT FROM AUTHOR]

• Hippocampal β-adrenergic system modulates reconsolidation of recognition memories. • Infusion of propranolol in the hippocampus impairs updating recognition memory trace. • Propranolol may affect elemental and conjunctive components of the memory. Targeting reconsolidation with propranolol, a blocker of β-adrenergic receptors (β-ARs), emerged as a potential treatment for maladaptive memories such as those involved in posttraumatic stress disorder (PTSD). Reconsolidation targeting treatments for PTSD are becoming a common practice in the clinic and it is important to unveil any side effects upon 'non-targeted' memories. While previous studies have focused on propranolol's effects on the reconsolidation of emotional/distressful memories, the present study asked whether propranolol is involved in the reconsolidation of recognition memories - by assessing its effects on distinct memory components and the role of the dorsal hippocampus. Rats performed an object recognition (OR) task where they were exposed to different objects: A and B presented during the sample phase; A and C presented during the reactivation phase; and D in combination of either A, B, or C during a final test. Intra-hippocampal injections of propranolol (5 µg or 10 µg) were conducted immediately after the reactivation session. Propranolol infusions consistently impaired the addition of novel information to the previously consolidated memory trace regardless of dose, and the retention of familiar objects was not affected. Higher doses of propranolol also hindered memory of a familiar object that was not presented during the reactivation session, but was previously placed at the same location where novel information was presented during reactivation. The present results shed light on the role of β-ARs on the reconsolidation of different memory components and argue for the need for further studies examining possible recognition memory deficits following propranolol treatment. [ABSTRACT FROM AUTHOR]

The Graded Redefined Assessment of Strength, Sensibility, and Prehension Version 1 (GRASSP v1) is a validated measure of upper extremity impairment shown to be sensitive and responsive for traumatic cervical spinal cord injury (SCI) in both North American (NA) and European (EU) cohorts. The minimal clinically important difference (MCID) is the quantitative change in an assessment scale that patients perceive as being beneficial. Our aim was to establish the MCID of all subtests of the GRASSP v1 for cervical SCI. We prospectively analyzed 127 patients from NA and EU for up to six months after motor complete and incomplete cervical SCI using the GRASSP v1, Spinal Cord Independence Measure, and International Standards of Neurological Classification of Spinal Cord Injury. We used a patient global rating of change and the anchor-based method to calculate MCID of GRASSP v1 at six months post-injury. The MCID was established for the whole group, dividing the sample by "better" and "much better." Improvement in GRASSP v1 Strength and Prehension Performance scores of 13 and 3 are the MCID for the better category, and 19 and 7 are the MCID for the much better category, respectively. The MCID was also established for the motor complete and incomplete groups. Improvement in GRASSP v1 Strength and Prehension Performance scores of 12 and 6 are the MCID for the motor complete group, and 17 and 12 are the MCID for the motor incomplete group, respectively. The GRASSP v1 Strength subscore is the most sensitive for detecting meaningful clinical change in patients and is most closely related to measures of independence. Thus, use of GRASSP v1 Strength and Prehension Performance as measures of change is substantiated by this study. [ABSTRACT FROM AUTHOR]

Background: Spinal cord injury (SCI) has a significant impact on motor control and active force generation. Quantifying muscle activation following SCI may help indicate the degree of motor impairment and predict the efficacy of rehabilitative interventions. In healthy persons, muscle activation is typically quantified by electromyographic (EMG) signal amplitude measures. However, in SCI, these measures may not reflect voluntary effort, and therefore other nonamplitude-based features should be considered. Objectives: The purpose of this study was to assess the correlation of time-domain EMG features with the exerted joint torque (validity) and their test-retest repeatability (reliability), which may contribute to characterizing muscle activation following SCI. Methods: Surface EMG (SEMG) and torque were measured while nine uninjured participants and four participants with SCI performed isometric contractions of tibialis anterior (TA) and soleus (SOL). Data collection was repeated at a subsequent session for comparison across days. Validity and test-retest reliability of features were assessed by Spearman and intraclass correlation (ICC) of linear regression coefficients. Results: In healthy participants, SEMG features correlated well with torque (TA: ρ > 0.92; SOL: ρ > 0.94) and showed high reliability (ICCmean = 0.90; range, 0.72–0.99). In an SCI case series, SEMG features also correlated well with torque (TA: ρ > 0.86; SOL: ρ > 0.86), and time-domain features appeared no less repeatable than amplitude-based measures. Conclusion: Time-domain SEMG features are valid and reliable measures of lower extremity muscle activity in healthy participants and may be valid measures of sublesional muscle activity following SCI. These features could be used to gauge motor impairment and progression of rehabilitative interventions or in controlling assistive technologies. [ABSTRACT FROM AUTHOR]

Introduction: Dual tasking is common in activities of daily living (ADLs) and the ability to perform them usually declines with age. While cognitive aspects influence dual task (DT) performance, most DT-cost (DT-C) related metrics include only time- or speed- delta without weighting the accuracy of cognitive replies involved in the task. Objectives: The primary study goal was to weight the accuracy of cognitive replies as a contributing factor when estimating DT-C using a new index of DT-C that considers the accuracy of cognitive replies (P-index) in the instrumented timed up and go test (iTUG). Secondarily, to correlate the novel P-index with domains of the Mini-Mental State Examination (MMSE). Methods: Sixty-three participants (≥85 years old) took part in this study. The single task (ST) and DT iTUG tests were performed in a semi-random order. Both the time taken to complete the task measured utilizing an inertial measurement unit (IMU), and the accuracy of the cognitive replies were used to create the novel P-index. Clinical and sociodemographic data were collected. Results: The accuracy of the cognitive replies changed across the iTUG phases, particularly between the walk 1 and walk 2 phases. Moreover, weighting 0.6 for delta-time (W1) and 0.4 for cognitive replies (W2) into the P-index enhanced the prediction of the MMSE score. The novel P-index was able to explain 37% of the scores obtained by the fallers in the "spatial orientation" and "attention" domains of the MMSE. The ability of the P-index to predict MMSE scores was not significantly influenced by age, schooling, and number of medicines in use. The Bland-Altman analysis indicated a substantial difference between the time-delta-based DT-C and P-index methods, which was within the limits of agreement. Conclusions: The P-index incorporates the accuracy of cognitive replies when calculating the DT-C and better reflects the variance of the MMSE in comparison with the traditional time- or speed-delta approaches, thus providing an improved method to estimate the DT-C. [ABSTRACT FROM AUTHOR]

Traumatic spinal cord injury (SCI) disrupts spinal and supraspinal pathways, and this process is reflected in changes in surface electromyography (sEMG). sEMG is an informative complement to current clinical testing and can capture the residual motor command in great detail-including in muscles below the level of injury with seemingly absent motor activities. In this comprehensive review, we sought to describe how the sEMG properties are changed after SCI. We conducted a systematic literature search followed by a narrative review focusing on sEMG analysis techniques and signal properties post-SCI. We found that early reports were mostly focused on the qualitative analysis of sEMG patterns and evolved to semi-quantitative scores and a more detailed amplitude-based quantification. Nonetheless, recent studies are still constrained to an amplitude-based analysis of the sEMG, and there are opportunities to more broadly characterize the time- and frequency-domain properties of the signal as well as to take fuller advantage of high-density EMG techniques. We recommend the incorporation of a broader range of signal properties into the neurophysiological assessment post-SCI and the development of a greater understanding of the relation between these sEMG properties and underlying physiology. Enhanced sEMG analysis could contribute to a more complete description of the effects of SCI on upper and lower motor neuron function and their interactions, and also assist in understanding the mechanisms of change following neuromodulation or exercise therapy. [ABSTRACT FROM AUTHOR]

Background: Walking speed is often used in the clinic to assess the level of gait impairment following stroke. Nonetheless, post-stroke individuals may employ the same walking speed but at a distinct movement quality. The main objective of this study was to explore a novel movement quality metric, the estimation of gait smoothness by the spectral arc length (SPARC), in individuals with a chronic stroke displaying mild/moderate or severe motor impairment while walking in an outdoor environment. Also, to quantify the correlation between SPARC, gait speed, motor impairment, and lower limb spasticity focused on understanding the relationship between the movement smoothness metric and common clinical assessments. Methods: Thirty-two individuals with a chronic stroke and 32 control subjects participated in this study. The 10 meters walking test (10 MWT) was performed at the self-selected speed in an outdoor environment. The 10 MWT was instrumented with an inertial measurement unit system (IMU), which afforded the extraction of trunk angular velocities (yaw, roll, and pitch) and subsequent SPARC calculation. Results: Movement smoothness was not influenced by gait speed in the control group, indicating that SPARC may constitute an additional and independent metric in the gait assessment. Individuals with a chronic stroke displayed reduced smoothness in the yaw and roll angular velocities (lower SPARC) compared with the control group. Also, severely impaired participants presented greater variability in smoothness along the 10 MWT. In the stroke group, a smoother gait in the pitch angular velocity was correlated with lower limb spasticity, likely indicating adaptive use of spasticity to maintain the pendular walking mechanics. Conversely, reduced smoothness in the roll angular velocity was related to pronounced spasticity. Conclusions: Individuals with a chronic stroke displayed reduced smoothness in the yaw and roll angular velocities while walking in an outdoor environment. The quantification of gait smoothness using the SPARC metric may represent an additional outcome in clinical assessments of gait in individuals with a chronic stroke. [ABSTRACT FROM AUTHOR]

Aging-related neuromuscular and neurocognitive decline induces unsmooth movements in daily functional mobility. Here, we used a robust analysis of linear and angular spectral arc length (SPARC) in the single and dual task instrumented timed up-and-go (iTUG) test to compare functional mobility smoothness in fallers and non-fallers aged 85 and older. 64 participants aged 85 and older took part in this case control study. The case group (fallers, n = 32) had experienced falls to the ground in the 6 months prior to the assessment. SPARC analyses were conducted in all phases of the single and dual task iTUGs. We also performed correlation mapping to test the relation of socio-demographic and clinical features on SPARC metrics. The magnitude of between-group differences was calculated using D-Cohen effect size (ES). SPARC was able to distinguish fallers during the single iTUG (ES ≈ 4.18). Turning while walking in the iTUG induced pronounced unsmooth movements in the fallers (SPARC ≈ −13; ES = 3.52) and was associated with the ability to maintain balance in the functional reach task. This information is of importance in the study of functional mobility in the oldest-old and to assess the efficacy of fall-prevention programs. [ABSTRACT FROM AUTHOR]

von Monakow's theory of diaschisis states the functional 'standstill' of intact brain regions that are remote from a damaged area, often implied in recovery of function. Accordingly, neural plasticity and activity patterns related to recovery are also occurring at the same regions. Recovery relies on plasticity in the periinfarct and homotopic contralesional regions and involves relearning to perform movements. Seeking evidence for a relearning mechanism following stroke, we found that rodents display many features that resemble classical learning and memory mechanisms. Compensatory relearning is likely to be accompanied by gradual shaping of these regions and pathways, with participating neurons progressively adapting cortico-striato-thalamic activity and synaptic strengths at different cortico-thalamic loops – adapting function relayed by the striatum. Motor cortex functional maps are progressively reinforced and shaped by these loops as the striatum searches for different functional actions. Several cortical and striatal cellular mechanisms that influence motor learning may also influence post-stroke compensatory relearning. Future research should focus on how different neuromodulatory systems could act before, during or after rehabilitation to improve stroke recovery. [ABSTRACT FROM AUTHOR]

Background:Recently a new shoe design with air compartments at the insole has been developed and termed as toning shoes. However, it is unclear how this air compartments-based shoe could affect muscle activation and centre of pressure during treadmill walking or quiet standing. Purpose:The aim of this study was to compare muscular activation during treadmill walking and quiet standing between toning shoes and regular shoes. Methods:Ten participants performed treadmill walking at 4.5 km.h−1and unipodal standing wearing regular shoes and toning shoes in random order. Mean muscular activation of seven muscles from preferred lower limb (tibialis anterior,soleus,peroneus brevis,biceps femoris,gastrocnemius medialis,vastus lateralis, andrectus femoris) at different phases of the gait cycle (first half of contact, second half of contact and balance time) were assessed and compared between regular and toning shoes. Coefficient of variation and centre of pressure were calculated for temporal parameters and compared between regular and toning shoes. Principal results:Toning shoes led to higher coefficient of variation (20% during contact time; 15% during balance time), which may indicate a more unstable walking dynamic. Furthermore, the main muscular activation outcome was a 7% higher activation forrectus femorisand 7% lower activation forvastus lateralisat first half of contact time and higher activation forvastus lateralis(8%) and lower activation forrectus femoris(15%) at second half of contact time. Centre of pressure excursion and muscular activation during standing presented no significant differences. Conclusion:Toning shoe usage is increasing among the population and a better knowledge of effects on muscular activation and postural balance is fundamental. Toning shoes use resulted in a change in muscular activation during treadmill walking mainly for the quadriceps muscle. Some other muscle groups showed small differences in muscular activation patterns. There were no differences in postural balance and muscular activity during quiet standing with toning shoes use. [ABSTRACT FROM PUBLISHER]

Mobility smoothness assessed by the spectral arc length (SPARC) may reflect the complex biomechanical alterations that occur with aging and may help detect functional mobility changes after experiencing falls. Here, we sought to explore whether smoothness of angular velocities of the trunk measured using SPARC metrics in the instrumented timed-up-and-go (iTUG) test are assoacited with a history of falls in the oldest-old. A case-control study. The sample consisted of 64 community-dwelling oldest-old individuals who underwent the following assessments: clinical and sociodemographic questionnaire, Mini Mental State Examination (MMSE), Falls Efficacy-questionnaire International (FES I), the Activities-specific Balance Confidence (ABC), Functional Reaching Test (FRT), and the iTUG test. We used an inertial measurement unit (IMU) to obtain trunk angular velocities from the IMU's gyroscope, which was used to calculate mobility smoothness (SPARC). Standard deviation of the mobility smoothness around the anteroposterior axis of rotation (SPARC roll SD) (OR: 6.15 / CI 95 % = 1.58–23.94) and duration (OR: 1.11 / CI 95 % = 1.09–1.22) in the full iTUG test were associated with a history of falls in oldest-old. Using solely the full iTUG duration (59.19 ± 2.18) or SPARC (61.87 ± 2.40) resulted in lower probability to detect a history of falls in comparison with the combined measurement (66.21 ± 2.50). SPARC roll SD in the full iTUG may be a relevant biomarker to detect mobility smoothness changes in the oldest-old. This study provides evidence the oldest-old with a history of falls may change their functional mobility, in terms of movement duration and smoothness. • SPARC distills the complex functional mobility smoothness into a single measure. • SPARC and iTUG duration are linked with a history of falls in the oldest-old. • SPARC roll standard deviation better detect mobility smoothness in fallers. • iTUG time-based and SPARC metrics should be combined to assess functional mobility. [ABSTRACT FROM AUTHOR]

Current clinical practice guidelines support structured, progressive protocols for improving walking after stroke. Technology enables monitoring of exercise and therapy intensity, but safety concerns could also be addressed. This study explores functional mobility in post-stroke individuals using wearable technology to quantify movement smoothness—an indicator of safe mobility.Observational cohort study.A movement analysis and rehabilitation laboratory.A total of 56 chronic post-stroke individuals and 51 healthy controls.Participants performed the mobility test while wearing an inertial measurement unit attached to their waist. Thirty-two healthy participants also engaged in a steady-state walking task.Functional mobility smoothness by examining angular velocities in the yaw, pitch, and roll axes, employing the spectral arc length metrics.Our findings reveal that post-stroke individuals extend the duration of the timed-up-and-go test (≈9 s and 23 s longer compared to the controls) to ensure safe mobility—greater mobility smoothness (p < 0.001). Notably, for mild and severe impairments, post-stroke mobility demonstrated ≈8% and ≈11% greater smoothness in pitch movements, respectively (p = 0.025 and p = 0.002). In the roll direction, mobility was ≈12% smoother in cases of severe strokes (p = 0.006).This study addresses a crucial gap in the understanding of mobility smoothness in chronic stroke survivors using wearable technology. Our study suggests the potential utility of spectral arc length to predict challenging mobility situations in real-world situations. We highlight the potential for automated monitoring of safety offering promising avenues for real-time, real-life monitoring. [ABSTRACT FROM AUTHOR]