Aging Effect on Visuomotor Adaptation: Mediated by Cognitive Decline

Not fleeting but lasting: limited influence of aging on implicit adaptative motor learning and its short-term retention

In motor adaptation, learning is thought to rely on a combination of several processes. Two of these are implicit learning (incidental updating of the movement due to sensory prediction error) and explicit learning (intentional adjustment to reduce target error). The explicit component is thought to be fast adapting, whereas the implicit one is slow. The dynamic integration of such fast and slow components can lead to spontaneous recovery. That is, after prolonged adaptation of movement to a given perturbation, the learning is extinguished by presenting a perturbation in the opposite direction for a few trials. After such extinction, the learned adaptation can reappear in the absence of any further training, a phenomenon called spontaneous recovery. Trewartha et al. (Trewartha KM, Garcia A, Wolpert DM, Flanagan JR. J Neurosci 34: 13411-13421, 2014) found that older adults show less spontaneous recovery than their younger controls, indicating impairments in short-term retention of force-field adaptation. This disagrees with evidence suggesting that the implicit component and its retention do not decline with aging. To clarify this discrepancy, we performed a conceptual replication of that result. Twenty-eight healthy young and 20 healthy older adults learned to adapt to a forcefield perturbation in a paradigm known to elicit spontaneous recovery. Both groups adapted equally well to the perturbation. Implicit adaptation of the older subjects was indistinguishable from that of their younger counterparts. In addition, our conceptual replication failed to reproduce the result of Trewartha et al. (Trewartha KM, Garcia A, Wolpert DM, Flanagan JR. J Neurosci 34: 13411-13421, 2014) and found that the spontaneous recovery was also similar across groups. Our results reconcile previous studies by showing that both spontaneous recovery and implicit adaptation are unaffected by aging.NEW & NOTEWORTHY In this study, we tested whether aging influences the ability to learn to counteract a perturbation during reaching movements and to recall previously learned motor memories. In contrast to a previously published paper, we found that the ability of older participants to adapt to a perturbation and to recall motor memories remains unimpaired.

VR Cognitive-based Intervention for Enhancing Cognitive Functions and Well-being in Older Adults with Mild Cognitive Impairment: Behavioral and EEG Evidence

Objective: Mild cognitive impairment (MCI) has been recognized as a window of opportunity for therapeutic and preventive measures to slow cognitive decline. The current study investigated the efficacy of the virtual reality (VR) cognitive-based intervention on verbal and visuospatial short-term memory (STM), executive functions (EFs), and wellbeing among older adults with and without MCI. Method: The immersive VR cognitive-based intervention comprised eight 60-minute sessions, held twice a week over a span of 30 days. The participants consisted of 31 non-MCI older adults in the experimental group (mean age ± SD = 66.31 ± 3.12 years), 29 older adults with MCI in the experimental group (mean age ± SD = 68.19 ± 5.03 years), and 30 non-MCI older adults in the control group (mean age ± SD = 64.97 ± 3.35 years). The dependent variables were assessed by using a battery of computerized test, the well-being of older people questionnaire and resting-state EEG. A repeated-measures ANCOVA was employed to examine the effects of the developed VR intervention. Results: Significant improvements were observed in both STMs and EFs following the intervention, as indicated by behavioral and EEG findings, ranging from small to large effect sizes (i.e., = .05-.17). However, enhanced wellbeing was specifically observed among older adults with MCI in the experimental group, F(2, 87) = 6.78, p .01, = .11. Conclusions: The present findings lend support to the efficacy of VR cognitive-based interventions across clinical and non-clinical populations. These results underscore the immediate impact of the intervention across multimodal assessments, including neurophysiological changes, cognitive, and behavioral outcomes.

Exploring age-related differences in the relationship between spatial and temporal contributions to step length asymmetry during split-belt adaptation

Gait adaptability is crucial for meeting environmental demands, and impaired gait adaptation increases fall risk, particularly in older adults. While prior research exists on older adults' gait adaptation, particularly in perturbation studies, the specific contributions of temporal and spatial adaptation strategies to step length asymmetry (SLA) during split-belt treadmill walking require further examination. This study fills this gap by evaluating how distinct adaptation strategies contribute to SLA in healthy young and older adults. 19 healthy young adults (20.4 ± 1.1 years) and 19 healthy older adults (68.3 ± 8.1 years) walked on a split-belt treadmill requiring their non-dominant leg to move twice as fast as their dominant leg. Repeated measures ANOVA investigated (1) spatial and temporal contributions to SLA, (2) SLA across gait adaptation epochs, and (3) rates of adaptation and deadaptation. Older adults displayed reduced temporal contributions to SLA compared to younger adults (F1,36 = 6.42, p = .02, ŋ2 = .15), but no group differences were observed in spatial contributions to SLA (F1,36 = 3.23, p = .08, ŋ2 = .082). SLA during adaptation and deadaptation did not differ by age group, nor did the rate of adaptation (F1,34.7 = 0.594, p = .45) or deadaptation F1,33.6 = 2.886, p = .09). These findings suggest that while older adults rely less on temporal strategies for gait adaptation, but maintain overall adaptability comparable to younger adults. Findings enhance our understanding of age-related changes in gait adaptation mechanisms and may inform targeted interventions to improve gait adaptability in older populations.

Differential Aging Effects on Implicit and Explicit Sensorimotor Learning

Deterioration in motor control is a hallmark of aging, significantly contributing to a decline in quality of life. More controversial is the question of whether and how aging impacts sensorimotor learning. We hypothesized that the inconsistent picture observed in the current literature can be attributed to at least two factors. First, aging studies tend to be underpowered. Second, the learning assays used in these experiments tend to reflect, to varying degrees, the operation of multiple learning processes, making it difficult to make inferences across studies. We took a two-pronged approach to address these issues. We first performed a meta-analysis of the sensorimotor adaptation literature focusing on outcome measures that provide estimates of explicit and implicit components of adaptation. We then conducted two well-powered experiments to re-examine the effect of aging on sensorimotor adaptation, using behavioral tasks designed to isolate explicit and implicit processes. Convergently, both approaches revealed a striking dissociation: Older individuals exhibited a marked impairment in their ability to discover an explicit strategy to counteract a visuomotor perturbation. However, they exhibited enhanced implicit recalibration. We hypothesize that the effect of aging on explicit learning reflects an age-related decline in reasoning and problem solving, and the effect of aging on implicit learning reflects age-related changes in multisensory integration. Taken together, these findings deepen our understanding of the impact of aging on sensorimotor learning.

The independence of impairments in proprioception and visuomotor adaptation after stroke

BACKGROUND

Proprioceptive impairments are common after stroke and are associated with worse motor recovery and poor rehabilitation outcomes. Motor learning may also be an important factor in motor recovery, and some evidence in healthy adults suggests that reduced proprioceptive function is associated with reductions in motor learning. It is unclear how impairments in proprioception and motor learning relate after stroke. Here we used robotics and a traditional clinical assessment to examine the link between impairments in proprioception after stroke and a type of motor learning known as visuomotor adaptation.

METHODS

We recruited participants with first-time unilateral stroke and controls matched for overall age and sex. Proprioceptive impairments in the more affected arm were assessed using robotic arm position- (APM) and movement-matching (AMM) tasks. We also assessed proprioceptive impairments using a clinical scale (Thumb Localization Test; TLT). Visuomotor adaptation was assessed using a task that systematically rotated hand cursor feedback during reaching movements (VMR). We quantified how much participants adapted to the disturbance and how many trials they took to adapt to the same levels as controls. Spearman's rho was used to examine the relationship between proprioception, assessed using robotics and the TLT, and visuomotor adaptation. Data from healthy adults were used to identify participants with stroke who were impaired in proprioception and visuomotor adaptation. The independence of impairments in proprioception and adaptation were examined using Fisher's exact tests.

RESULTS

Impairments in proprioception (58.3%) and adaptation (52.1%) were common in participants with stroke (n = 48; 2.10% acute, 70.8% subacute, 27.1% chronic stroke). Performance on the APM task, AMM task, and TLT scores correlated weakly with measures of visuomotor adaptation. Fisher's exact tests demonstrated that impairments in proprioception, assessed using robotics and the TLT, were independent from impairments in visuomotor adaptation in our sample.

CONCLUSION

Our results suggest impairments in proprioception may be independent from impairments in visuomotor adaptation after stroke. Further studies are needed to understand factors that influence the relationship between motor learning, proprioception and other rehabilitation outcomes throughout stroke recovery.

Efficacy of cognitive training on executive functions in healthy older adults: a systematic review with meta-analysis of randomized controlled trials

OBJECTIVE

Systematically review randomized controlled trials on the efficacy of cognitive training on executive functions in healthy older people.

MEASURES

The outcome measures were related to inhibitory control, working memory, and cognitive flexibility.

RESULTS

Thirty-one trials were included in the systematic review and thirteen trials in the meta-analysis. In the overall analysis, the cognitive training enhanced inhibitory control when measured by the Stroop task (p < .001, d = 1.64) and working memory when measured by the Corsi Block task (p = .002, d = .16). A marginal significance was found for working memory in the Digit Span task - Forward (p = .06, d = .92). However, cognitive training did not enhance inhibitory control when measured by the Go/No-Go task (p = .76, d = .59), working memory when measured by the Digit Span - Backward (p = .72, d = .95) and N-Back (p = .10, d = .26) tasks, and cognitive flexibility when measured by Trail Making - Part B (p = .08, d = .27) and Semantic Fluency (p = .49, d = .06) tasks.

CONCLUSION

Mixed evidence was found for inhibitory control and working memory; cognitive flexibility showed no evidence of improvement.

Developmental and age differences in visuomotor adaptation across the lifespan

In the present cross-sectional study, we examined age and sex differences in sensorimotor adaptation. We tested 253 individuals at a local science museum (NEMO Science Museum, Amsterdam). Participants spanned a wide age range (8-70 years old; 54% male), allowing us to examine effects of both development and healthy aging within a single study. Participants performed a visuomotor adaptation task in which they had to adapt manual joystick movements to rotated visual feedback. We assessed the rate of adaptation following the introduction of the visual perturbation (both for early and later stages of adaptation), and the rate of de-adaptation following its removal. Results showed reliable adaptation patterns which did not differ by sex. We observed a quadratic relationship between age and both early adaptation and de-adaptation rates, with younger and older adults exhibiting the fasted adaptation rates. Our findings suggest that both younger and older age are associated with poorer strategic, cognitive processes involved in adaptation. We propose that developmental and age differences in cognitive functions and brain properties may underlie these effects on sensorimotor functioning.

Physical activity is associated with behavioral and neural changes across the lifespan

Physical activity is known to positively impact brain structure and function, but its effects on resting-state functional connectivity (rsFC) and its relationship with complex tasks as a function of age remain unclear. Here, we address these issues in a large population-based sample (N=540) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) repository. We relate levels of physical activity to rsFC patterns in magnetoencephalographic (MEG) and functional magnetic resonance imaging (fMRI) data, and to measures of executive function and visuomotor adaptation, across the lifespan. We show that higher self-reported daily physical activity is associated with lower alpha-band (8-12Hz) global coherence, indicating weaker synchrony of neural oscillations in this band. Physical activity affected between-network connectivity of resting-state functional networks, although its effects on individual networks did not survive correction for multiple comparisons. Furthermore, our results indicate that greater engagement in day-to-day physical activity is associated with better visuomotor adaptation, across the lifespan. Overall, our findings indicate that rsFC metrics indexed by MEG and fMRI are sensitive indicators of the brain's response to physical activity, and that a physically active lifestyle affects multiple aspects of neural function across the lifespan.

Age-related decline of online visuomotor adaptation: a combined effect of deteriorations of motor anticipation and execution

The literature has established that the capability of visuomotor adaptation decreases with aging. However, the underlying mechanisms of this decline are yet to be fully understood. The current study addressed this issue by examining how aging affected visuomotor adaptation in a continuous manual tracking task with delayed visual feedback. To distinguish separate contributions of the declined capability of motor anticipation and deterioration of motor execution to this age-related decline, we recorded and analyzed participants' manual tracking performances and their eye movements during tracking. Twenty-nine older people and twenty-three young adults (control group) participated in this experiment. The results showed that the age-related decline of visuomotor adaptation was strongly linked to degraded performance in predictive pursuit eye movement, indicating that declined capability motor anticipation with aging had critical influences on the age-related decline of visuomotor adaptation. Additionally, deterioration of motor execution, measured by random error after controlling for the lag between target and cursor, was found to have an independent contribution to the decline of visuomotor adaptation. Taking these findings together, we see a picture that the age-related decline of visuomotor adaptation is a joint effect of the declined capability of motor anticipation and the deterioration of motor execution with aging.

A Serious Game for the Assessment of Visuomotor Adaptation Capabilities during Locomotion Tasks Employing an Embodied Avatar in Virtual Reality

The study of visuomotor adaptation (VMA) capabilities has been encompassed in various experimental protocols aimed at investigating human motor control strategies and/or cognitive functions. VMA-oriented frameworks can have clinical applications, primarily in the investigation and assessment of neuromotor impairments caused by conditions such as Parkinson's disease or post-stroke, which affect the lives of tens of thousands of people worldwide. Therefore, they can enhance the understanding of the specific mechanisms of such neuromotor disorders, thus being a potential biomarker for recovery, with the aim of being integrated with conventional rehabilitative programs. Virtual Reality (VR) can be entailed in a framework targeting VMA since it allows the development of visual perturbations in a more customizable and realistic way. Moreover, as has been demonstrated in previous works, a serious game (SG) can further increase engagement thanks to the use of full-body embodied avatars. Most studies implementing VMA frameworks have focused on upper limb tasks and have utilized a cursor as visual feedback for the user. Hence, there is a paucity in the literature about VMA-oriented frameworks targeting locomotion tasks. In this article, the authors present the design, development, and testing of an SG-based framework that addresses VMA in a locomotion activity by controlling a full-body moving avatar in a custom VR environment. This workflow includes a set of metrics to quantitatively assess the participants' performance. Thirteen healthy children were recruited to evaluate the framework. Several quantitative comparisons and analyses were run to validate the different types of introduced visuomotor perturbations and to evaluate the ability of the proposed metrics to describe the difficulty caused by such perturbations. During the experimental sessions, it emerged that the system is safe, easy to use, and practical in a clinical setting. Despite the limited sample size, which represents the main limitation of the study and can be compensated for with future recruitment, the authors claim the potential of this framework as a useful instrument for quantitatively assessing either motor or cognitive impairments. The proposed feature-based approach gives several objective parameters as additional biomarkers that can integrate the conventional clinical scores. Future studies might investigate the relation between the proposed biomarkers and the clinical scores for specific disorders such as Parkinson's disease and cerebral palsy.

Visual-spatial and visuomotor functioning in adults with neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a neurodevelopmental genetic disorder associated with visual-spatial and visuomotor deficits, which have not been studied well in adults with NF1.

METHODS

In 22 adults with NF1 and 31 controls, visuomotor functioning was assessed by measuring eye latency, hand latency and hand accuracy during visuomotor tasks. Visual-spatial functioning was assessed by measuring eye movement responses during the Visual Threshold Task.

RESULTS

The NF1 group had a significantly shorter eye latency than the control group and was less accurate in their hand movements during specific visuomotor tasks. The groups showed no differences in eye movement responses during the Visual Threshold Task and in hand latency during the visuomotor tasks.

CONCLUSIONS

In contrast to studies in children with NF1, we found no alterations in visual-spatial information processing in adults. Impairments in eye latency and hand accuracy during specific visuomotor tasks may indicate deficits in visuomotor functioning in adults with NF1.

Application of Immersive Virtual-Reality-Based Puzzle Games in Elderly Patients with Post-Stroke Cognitive Impairment: A Pilot Study

Background: The society is aging in China, and the cognitive level of elderly post-stroke patients gradually declines. Face-to-face cognitive functional training is no longer sufficient. Immersive virtual reality (IVR) is a promising rehabilitation training device. In this study, we developed an IVR-based puzzle game to explore its effectiveness, feasibility, and safety in elderly stroke patients with cognitive dysfunction. Methods: A total of 30 patients with mild post-stroke cognitive impairment after stroke were randomly assigned to a control or IVR group. Patients in both groups received routine rehabilitation therapy. Patients in the control group received traditional cognitive training, and those in the IVR group received IVR-based puzzle game therapy. Before and after treatment, Montreal cognitive assessment (MOCA), trail-making test-A (TMT-A), digit symbol substitution test (DSST), digital span test (DST), verbal fluency test (VFT), and modified Barthel index (MBI) were evaluated in both groups. In addition, the IVR group was administered a self-report questionnaire to obtain feedback on user experience. Results: There was no significant difference in the baseline data between the two groups. After six weeks of treatment, the cognitive assessment scores were improved in both groups. Moreover, the IVR group showed more improvements than the control group in the DSST (Z = 2.203, p = 0.028 < 0.05, η2 = 0.16); MOCA (T = 1.186, p = 0.246 > 0.05, d = 0.44), TMT-A (T = 1.791, p = 0.084 > 0.05, d = 0.65), MBI (T = 0.783, p = 0.44 > 0.05, d = 0.28), FDST (Z = 0.78, p = 0.435 > 0.05, η2 = 0.02), BDST (Z = 0.347, p = 0.728 > 0.05, η2 = 0.004), and VFT(Z = 1.087, p = 0.277 > 0.05, η2 = 0.039) did not significantly improve. The significant difference in DSST represents an improvement in executive function and visual−spatial cognitive characteristics. The other assessment scores did not show such features. Therefore, we did not observe significant differences through this measure. According to the results of the self-report questionnaire, most of the patients were satisfied with the equipment stability and training content. Several individuals reported mild adverse reactions. Conclusions: This pilot study suggests that IVR-based puzzle games are a promising approach to improve post-stroke cognitive function, especially executive cognitive function, and visual−spatial attention in older adults.

Virtual Reality-based Cognitive Intervention for Enhancing Executive Functions in Community-dwelling Older Adults

With the rapid growth of the older population globally, it is anticipated that age-related cognitive decline in the prodromal phase and more severe pathological decline will increase. Moreover, currently, no effective treatment options for the disease exist. Thus, early and timely prevention actions are promising and prior strategies to preserve cognitive functions by preventing symptomatology from increasing the age-related deterioration of the functions in healthy older adults. This study aims to develop the virtual reality-based cognitive intervention for enhancing executive functions (EFs) and examine the EFs after training with the virtual reality-based cognitive intervention in community-dwelling older adults. Following inclusion/exclusion criteria, 60 community-dwelling older adults aged 60-69 years were involved in the study and randomly divided into passive control and experimental groups. Eight 60 min virtual reality-based cognitive intervention sessions were held twice a week and lasted for 1 month. The EFs (i.e., inhibition, updating, and shifting) of the participants were assessed by using standardized computerized tasks, i.e., Go/NoGo, forward and backward digit span, and Berg's card sorting tasks. Additionally, a repeated-measure ANCOVA and effect sizes were applied to investigate the effects of the developed intervention. The virtual reality-based intervention significantly improved the EFs of older adults in the experimental group. Specifically, the magnitudes of enhancement were observed for inhibitory as indexed by the response time, F(1) = 6.95, p < .05, η_p² = .11, updating as represented by the memory span, F(1) = 12.09, p < .01, η_p² = .18, and the response time, F(1) = 4.46, p = .04, η_p² = .07, and shifting abilities as indexed by the percentage of correct responses, F(1) = 5.30, p = .03, η_p² = .09, respectively. The results indicated that the simultaneous combined cognitive-motor control as embedded in the virtual-based intervention is safe and effective in enhancing EFs in older adults without cognitive impairment. Nevertheless, further studies are required to investigate the benefits of these enhancements to motor functions and emotional aspects relating to daily living and the well-being of older populations in communities.