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Conventional transcranial direct-current stimulation (tDCS) delivered to the primary motor cortex (M1) has been shown to enhance implicit motor sequence learning (IMSL). Conventional tDCS targets M1 but also the motor association cortices (MAC), making the precise contribution of M1 to IMSL presently unclear. We aimed to address the roles of these areas by comparing conventional tDCS of M1 and MAC to High-Definition (HD) tDCS, which more focally targets M1. In this sham-controlled, crossover study in 89 healthy adults, we used mixed-effects models to analyze sequence-specific and general learning effects in the acquisition, short- and long-term consolidation phases of IMSL, as measured by the serial reaction time task. Conventional tDCS did not influence general learning, improved sequence-specific learning during acquisition (anodal: M=42.64 ms, sham: M=32.87 ms, p=.041) and deteriorated it at long-term consolidation (anodal: M=75.37 ms, sham: M=86.63 ms, p=.019). HD tDCS did not influence general learning, slowed performance specifically in sequential blocks across all learning phases (all p’s

We compared changes in spatiotemporal gait parameters of 11 healthy older adults (mean age: 88.6 years) over 3 conditions of walking with the Honda Walking Assist (HWA), a hip-assistive exoskeleton. Differences in 14 gait parameters between (1) normal overground walking, (2) walking with a nonassisting HWA, and (3) optimally assisting HWA were analyzed using Friedman and Wilcoxon signed rank tests. Significant differences depending on type of assistance were found for 9 parameters. None persisted following Bonferroni corrections. Single-session individualized HWA assistance does not induce immediate changes in gait parameters. This does not contradict the potential of multiple training sessions with the HWA.

Implicit motor sequence learning (IMSL) is a cognitive function that is known to be directly associated with impaired motor function in Parkinson's disease (PD). Research on healthy young participants shows the potential for transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique, over the primary motor cortex (M1) to enhance IMSL. tDCS has direct effects on the underlying cortex, but also induces distant (basal ganglia) network effects-hence its potential value in PD, a prime model of basal ganglia dysfunction. To date, only null effects have been reported in persons with PD. However, these studies did not determine the reacquisition effects, although previous studies in healthy young adults suggest that tDCS specifically exerts its beneficial effects on IMSL on reacquisition rather than acquisition. In the current study, we will therefore establish possible reacquisition effects, which are of a particular interest, as long-term effects are vital for the successful functional rehabilitation of persons with PD. Using a sham-controlled, counterbalanced design, we will investigate the potential of tDCS delivered over M1 to enhance IMSL, as measured by the serial reaction time task, in persons with PD and a neurologically healthy age- and sex-matched control (HC) group. Multilevel Mixed Models will be implemented to analyze the sequence-specific aspect of IMSL (primary outcome) and general learning (secondary outcome). We will determine not only the immediate effects that may occur concurrently with the application of tDCS but also the short-term (5 min post-tDCS) and long-term (1 week post-tDCS) reacquisition effects.

BACKGROUND: Walking difficulties put an individual at high risk of falling, institutionalisation and even death. The use of robotical rehabilitation or assistive devices for walking has gained considerable interest as a means of improving patients’ gait abilities. OBJECTIVE: The aim of this research was to examine patients’ intrinsic motivation to train with a wearable hip exoskeleton (Honda Walking Assist). METHODS: Rehabilitation patients (stroke, medullar lesion, orthopaedic surgery) and elderly (> 65 yrs) with walking difficulties were recruited for this study (n= 23). Each walked with the Honda Walking Assist for 30 minutes during one therapy session and completed the Intrinsic Motivation Inventory (IMI) afterwards. RESULTS: All participants presented with high scores on the IMI, in particular for the items ‘interest/enjoyment’ (median: 43; 25th–75th perc.: 37–46; maximal score: 49), ‘perceived competence of walking’ (35 [31–38]; max. score 42) and ‘value/usefulness’ (44 [35–49]; max. score 49). CONCLUSIONS: This robotic exoskeleton for assisted walking was considered a valuable device by the majority of participants, eliciting a high degree of motivation and enjoyment.

Implicit motor sequence learning (IMSL) is affected in Parkinson's disease (PD). Research in healthy young participants shows the potential for transcranial direct-current stimulation (tDCS) over the primary motor cortex (M1) to enhance IMSL. In PD, only null effects have been reported to date. We determined concurrent, short-term, and long-term effects of anodal tDCS over M1 on IMSL, as measured by the serial reaction time (SRT) task, in persons with PD with mild cognitive impairment (MCI). Concurrent (anodal/sham tDCS intervention during the SRT task), short-term (5 min post-intervention), and long-term (1 week post-intervention) effects on IMSL were evaluated in persons with idiopathic PD (Hoehn and Yahr stage II-III) with MCI. Results of 11 persons with PD (8 men and 3 women; mean age = 77.1 years; mean disease duration = 7.7 years) showed significant IMSL in the anodal (p = .016), but not in the sham tDCS condition (p = .937). Post-hoc analyses showed that IMSL reached statistical significance at 1 week post-intervention (p < .001). Anodal tDCS over M1 exerted beneficial effects on IMSL in persons with PD with MCI, in particular one week post-intervention. Our study is the first to report a positive effect of tDCS on IMSL in PD. Further research should include a larger, more cognitively diverse sample and additional follow-up periods.

Objective: Various studies investigated implicit sequence learning in Parkinson's disease (PD) by means of the traditional motor Serial Reaction Time (SRT) task and found a general pattern of impaired sequence learning. However, as perceptual and motor sequences of the SRT-task were correlated in previous studies, implicit sequential knowledge acquisition that is tested independently from motor sequences remains to be determined in PD. In this study, we investigated implicit sequence learning independently from motor sequence learning in individuals with PD. To this end, we used a perceptual SRT-task that did not rely upon sequential motor knowledge. Method: We measured response times (RTs) of 19 participants with PD (Hoehn & Yahr II or III; mean age 65) and 18 age-matched healthy controls (HC; mean age 61.5) in a perceptual SRT-task. General learning effects and sequence-specific learning effects were analyzed using repeated measures ANOVAs. Results: A significant decreasing linear trend (p < .001) in RTs was revealed in both the PD and HC groups as the SRT-task progressed, indicating general learning effects. Notably, a significant, strong main effect of sequence-specific learning occurred (p < .001), irrespective of group (p = .436). Sequence-specific learning did not differ significantly between the PD (M = 156.5 ms; SD = 50.7) and HC group (M = 173.0 ms; SD = 104.2). Bayesian analyses confirmed this as evidence of absence of an effect (B₁₀ = 3.543). Conclusions: Our results suggest that, at least in Hoehn & Yahr stages II and III, implicit sequential knowledge acquisition may be preserved in individuals with PD, when tested independently from motor sequence learning. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

An ALE meta-analysis focused on the serial reaction time task published in NeuroImage (Janacsek et al., 2019) demonstrated consistent activation of the basal ganglia across neuroimaging studies featuring sequence ​> ​random block contrasts and no consistent cerebellar activation. To enable valid conclusions regarding the role of the cerebellum in this context, some of the included studies should be excluded (e.g., because the cerebellum was explicitly not scanned). After omitting 6 of 16 studies/subject groups, 70% of the remaining studies did report cerebellar activation. While an ALE analysis of the remaining contrasts confirmed the original results, it may lack the power to detect cerebellar effects. We argue the conclusion that the cerebellum is not involved in sequence-specific learning should be treated with caution.