Motor Skill Training Effect on Real-Time Prefrontal Cortex Activation During Walking

We aimed to test the effects of motor skill training (MST) on gait automaticity measured by changes in prefrontal cortex (PFC) activation during actual walking. We used data from a 12-week trial of older adults (mean age=75.5, 60.5% women) randomized to standard physical therapy and standard+MST in a 1:1 ratio. Functional near infrared spectroscopy (fNIRS) measured PFC activation during simple and dual task walking. We will apply linear mixed models to assess effects of task, time, and MST on PFC activation. We will compare the PFC activation 1) during dual task walking compared to simple walking; 2) across visits after intervention; and 3) between participants receiving MST compared to standard physical therapy. These results will demonstrate whether gait automaticity, as evidenced by PFC activation during walking, is affected by MST.

Mobility Performance in Old Age: A Window Into Brain Integrity

Over two decades of research has established brain aging as a critical component of mobility decline. Studies consistently report that motor slowing predicts cognitive decline and neurodegenerative diseases, but reported associations are often modest. Both mobility and brain aging are complex processes and steady-state assessments are typically used (usual pace gait and structural MRI). We aim to elucidate the complex relations between brain aging and mobility by considering (a) strategies to maintain function such as interlacing periods of activity and rest (fractionation), (b) interventions that target brain and body (motor skill training), (c) multimodal neuroimaging (functional connectivity and cerebral small vessel disease (cSVD)), (d) challenged walking (dual-tasks, uneven surfaces), and (e) reduced resources (hearing loss). This symposium focuses on community-dwelling older adults from observational and intervention studies using state-of-the-art and real-life assessments of gait (quality and fragmentation by tri-axial accelerometry) and brain (near-infrared spectroscopy (fNIRS), resting-state functional MRI). First, we examine activity strategies that modify the relation between slow gait and AD risk (Tian). Second, using fNIRS, we investigate the extent to which motor skill training increases automaticity of gait (Chen). Third, we examine how functional connectivity may compensate for the detrimental effects of cSVD on mild parkinsonian signs (Hengenius). Fourth, we investigate the effects of challenged walking on gait quality and the relation with cognitive function (Suri). Finally, we demonstrate relations of hearing and cognition with mobility (Pupo). We seek to generate discussions on shared pathways underlying motor slowing and the aging brain and future prevention and intervention strategies.

Changes in GPS-Derived Community Mobility After Motor Skill Training in Older Adults

The study purpose was to identify the effects of a motor skill training intervention to improve gait speed on community mobility among community-dwelling older adults. The study included 249 participants randomized to standard physical therapy or a standard plus motor skill training program. Community mobility was measured using the Life Space Assessment (LSA) and GPS at baseline, 12 (post-intervention), 24 and 36 weeks. There were 124 participants (M age=77.4±6.7; 68.6% female; LSA: 76.2±17.6) randomized to the standard plus and 125 (M age=77.4±6.4; 62.4% female; LSA: 74.3±18.2) to the standard group. There was no significant between-group difference in pre- or post-intervention LSA scores and no significant pre- to post-intervention change over time in either group. GPS results are pending. While there were no differences in self-reported LSA, we anticipate objective GPS measurement of community mobility will better capture post-intervention changes and differences between groups.

Brain Patterns During Single- and Dual-Task Leg Movements

The brain is able to engage in dual tasks such as motor imagery (MI) and action observation (AO) or motor execution (ME) with action observation. In this study, we have quantitatively compared event-related desynchronization (ERD) patterns during tasks of pure MI, MI with AO (O-MI), ME, and ME with AO (O-ME) of the leg to investigate the underlying neuronal mechanisms using EEG. Subjects were instructed to imagine or perform rhythmical actions while watching a video of leg movements during O-MI and O-ME tasks; In contrast, subjects imagined and performed the leg movements without observing any video during pure MI and ME tasks. We noticed that the amplitude of ERDs from MI, O-MI, ME and O-ME sequentially increases in central regions of the brain. These quantified ERD patterns in EEG were used to study the differences of brain oscillatory changes among the four tasks. We found that ERDs in motor area were more distinct in O-MI, compared with pure MI. These results suggest that O-MI produced stronger motor activations than MI. Plus, O-ME showed significantly greater activations than ME in the beta band. O-ME has produced stronger neurophysiological effects than MI, and stronger behavioral effects than ME. These empirical results do provide convincing evidence of the dual tasks such combined MI or ME with action observation on brain pattern changes. The video of the goal-directed leg movements is most likely able to improve the ability of performing or imagining movements. O-MI and O-ME may get better and closer therapeutic effects in leg rehabilitation and motor skill training. Furthermore, the extent analysis of ERD may provide the basis for evaluating the ability of O-MI and O-ME in leg rehabilitation and motor skill training.

No add-on effects of Unilateral and Bilateral Transcranial Direct Current Stimulation on Fine Motor Skill Training Outcome in Chronic Stroke. A Randomized Controlled Trial

Background: Transcranial direct current stimulation (tDCS) may improve motor recovery after stroke. This study investigated if uni- and bihemispheric tDCS of the motor cortex can enhances fine motor training outcome and transfer to clinical assessments of upper motor function. Methods: In a randomized, double-blinded, sham-controlled trial, forty chronic stroke patients underwent five days of fine motor skill training of the paretic hand with either unilateral or bilateral (N=15/group) or placebo tDCS (N=10). Immediate and long-term (three months) effects on training outcome and motor recovery (Upper Extremity Fugl-Meyer, UE-FM, Wolf Motor Function Test, WMFT) were investigated. Results: Trained task performance significantly improved independently of tDCS in a curvilinear fashion. Anodal, but not dual tDCS resulted in a steeper learning curve on the UE-FM. Neither training nor combined training-tDCS improved WMFT performance.Conclusions: Fine motor skill training can facilitate recovery of upper extremity function. Minimal add-on effects of tDCS were observed.Clinical Trial Registration-URL: NCT01969097 retrospectively registered on 25/10/2013.