Neurophysiological models of rehabilitation and recovery suggest that a large volume of specific practice is required to induce the neuroplastic changes that underlie behavioral recovery. The primary ...objective of this meta-analysis was to explore the relationship between time scheduled for therapy and improvement in motor therapy for adults after stroke by (1) comparing high doses to low doses and (2) using metaregression to quantify the dose-response relationship further.
Databases were searched to find randomized controlled trials that were not dosage matched for total time scheduled for therapy. Regression models were used to predict improvement during therapy as a function of total time scheduled for therapy and years after stroke.
Overall, treatment groups receiving more therapy improved beyond control groups that received less (g=0.35; 95% confidence interval, 0.26-0.45). Furthermore, increased time scheduled for therapy was a significant predictor of increased improvement by itself and when controlling for linear and quadratic effects of time after stroke.
There is a positive relationship between the time scheduled for therapy and therapy outcomes. These data suggest that large doses of therapy lead to clinically meaningful improvements, controlling for time after stroke. Currently, trials report time scheduled for therapy as a measure of therapy dose. Preferable measures of dose would be active time in therapy or repetitions of an exercise.
Transcranial magnetic stimulation (TMS) facilitates the measurement of inhibitory and facilitatory influences of distal cortical regions over primary motor cortex (M1) during behaviour with excellent ...temporal resolution.These methods reveal that PMd transiently modulates inhibitory output on M1 during motor preparation across several classes of reaction time task. Direction of inhibition modulation depends on whether M1 effector representations are selected or nonselected for movement. Timing of inhibition modulation correlates with task cognitive demands.A theoretical framework to explain current findings and inform future predictions is lacking. Recent advances in the field of single-neuron recording research in nonhuman primates may provide a new way to think about the functional role of PMd–M1 inhibition switches.One influential hypothesis models PMd activity as a dynamical system. Available TMS data fit well with some of the predictions of this model.Research combining methods is needed to clarify whether these methods measure common processes.
Transcranial magnetic stimulation (TMS) research has furthered understanding of human dorsal premotor cortex (PMd) function due to its unrivalled ability to measure the inhibitory and facilitatory influences of PMd over the primary motor cortex (M1) in a temporally precise manner. TMS research indicates that PMd transiently modulates inhibitory output to effector representations within M1 during motor preparation, with the direction of modulation depending on which effectors are selected for response, and the timing of modulations co-varying with task selection demands. In this review, we critically assess this literature in the context of a dynamical systems approach used to model nonhuman primate (NHP) PMd/M1 single-neuron recordings during action preparation. Through this process, we identify gaps in the literature and propose future experiments.
The first Stroke Recovery and Rehabilitation Roundtable established a game changing set of new standards for stroke recovery research. Common language and definitions were required to develop an ...agreed framework spanning the four working groups: translation of basic science, biomarkers of stroke recovery, measurement in clinical trials and intervention development and reporting. This paper outlines the working definitions established by our group and an agreed vision for accelerating progress in stroke recovery research.
There is evidence for beneficial effects of acute and long-term exercise interventions on several forms of memory, including procedural motor learning. In the present study we examined how performing ...a single bout of continuous moderate intensity aerobic exercise would impact motor skill acquisition and retention in young healthy adults, compared to a period of rest. We hypothesized that exercise would improve motor skill acquisition and retention, compared to motor practice alone.
Sixteen healthy adults completed sessions of aerobic exercise or seated rest that were immediately followed by practice of a novel motor task (practice). Exercise consisted of 30 minutes of continuous cycling at 60% peak O2 uptake. Twenty-four hours after practice, we assessed motor learning with a no-exercise retention test (retention). We also quantified changes in offline motor memory consolidation, which occurred between practice and retention (offline). Tracking error was separated into indices of temporal precision and spatial accuracy.
There were no differences between conditions in the timing of movements during practice (p = 0.066), at retention (p = 0.761), or offline (p = 0.966). However, the exercise condition enabled participants to maintain spatial accuracy during practice (p = 0.477); whereas, following rest performance diminished (p = 0.050). There were no significant differences between conditions at retention (p = 0.532) or offline (p = 0.246).
An acute bout of moderate-intensity aerobic exercise facilitated the maintenance of motor performance during skill acquisition, but did not influence motor learning. Given past work showing that pairing high intensity exercise with skilled motor practice benefits learning, it seems plausible that intensity is a key modulator of the effects of acute aerobic exercise on changes in complex motor behavior. Further work is necessary to establish a dose-response relationship between aerobic exercise and motor learning.
The first Stroke Recovery and Rehabilitation Roundtable established a game changing set of new standards for stroke recovery research. Common language and definitions were required to develop an ...agreed framework spanning the four working groups: translation of basic science, biomarkers of stroke recovery, measurement in clinical trials and intervention development and reporting. This paper outlines the working definitions established by our group and an agreed vision for accelerating progress in stroke recovery research.
The most difficult clinical questions in stroke rehabilitation are “What is this patient’s potential for recovery?” and “What is the best rehabilitation strategy for this person, given her/his ...clinical profile?” Without answers to these questions, clinicians struggle to make decisions regarding the content and focus of therapy, and researchers design studies that inadvertently mix participants who have a high likelihood of responding with those who do not. Developing and implementing biomarkers that distinguish patient subgroups will help address these issues and unravel the factors important to the recovery process. The goal of the present paper is to provide a consensus statement regarding the current state of the evidence for stroke recovery biomarkers. Biomarkers of motor, somatosensory, cognitive and language domains across the recovery timeline post-stroke are considered; with focus on brain structure and function, and exclusion of blood markers and genetics. We provide evidence for biomarkers that are considered ready to be included in clinical trials, as well as others that are promising but not ready and so represent a developmental priority. We conclude with an example that illustrates the utility of biomarkers in recovery and rehabilitation research, demonstrating how the inclusion of a biomarker may enhance future clinical trials. In this way, we propose a way forward for when and where we can include biomarkers to advance the efficacy of the practice of, and research into, rehabilitation and recovery after stroke.
The objectives of the present study were to evaluate the impact of a single bout of high-intensity aerobic exercise on 1) long-term potentiation (LTP)-like neuroplasticity via response to paired ...associative stimulation (PAS) and 2) the temporal and spatial components of sequence-specific implicit motor learning. Additionally, relationships between exercise-induced increases in systemic brain-derived neurotrophic factor (BDNF) and response to PAS and motor learning were evaluated. Sixteen young healthy participants completed six experimental sessions, including the following: 1) rest followed by PAS; 2) aerobic exercise followed by PAS; 3) rest followed by practice of a continuous tracking (CT) task and 4) a no-exercise 24-h retention test; and 5) aerobic exercise followed by CT task practice and 6) a no-exercise 24-h retention test. The CT task included an embedded repeated sequence allowing for evaluation of sequence-specific implicit learning. Slope of motor-evoked potential recruitment curves generated with transcranial magnetic stimulation showed larger increases when PAS was preceded by aerobic exercise (59.8% increase) compared with rest (14.2% increase, P = 0.02). Time lag of CT task performance on the repeated sequence improved under the aerobic exercise condition from early (-100.8 ms) to late practice (-75.2 ms, P < 0.001) and was maintained at retention (-79.2 ms, P = 0.004) but did not change under the rest condition (P > 0.16). Systemic BDNF increased on average by 3.4-fold following aerobic exercise (P = 0.003), but the changes did not relate to neurophysiological or behavioral measures (P > 0.42). These results indicate that a single bout of high-intensity aerobic exercise can prime LTP-like neuroplasticity and promote sequence-specific implicit motor learning.
Recovery of motor function after stroke involves relearning motor skills and is mediated by neuroplasticity. Recent research has focused on developing rehabilitation strategies that facilitate such ...neuroplasticity to maximize functional outcome poststroke. Although many molecular signaling pathways are involved, brain-derived neurotrophic factor (BDNF) has emerged as a key facilitator of neuroplasticity involved in motor learning and rehabilitation after stroke. Thus, rehabilitation strategies that optimize BDNF effects on neuroplasticity may be especially effective for improving motor function poststroke. Two potential poststroke rehabilitation strategies that consider the importance of BDNF are the use of aerobic exercise to enhance brain function and the incorporation of genetic information to individualize therapy. Converging evidence demonstrates that aerobic exercise increases BDNF production and consequently enhances learning and memory processes. Nevertheless, a common genetic variant reduces activity-dependent secretion of the BDNF protein. Thus, BDNF gene variation may affect response to motor rehabilitation training and potentially modulate the effects of aerobic exercise on neuroplasticity. This perspective article discusses evidence that aerobic exercise promotes neuroplasticity by increasing BDNF production and considers how aerobic exercise may facilitate the acquisition and retention of motor skills for poststroke rehabilitation. Next, the impact of the BDNF gene val66met polymorphism on motor learning and response to rehabilitation is explored. It is concluded that the effects of aerobic exercise on BDNF and motor learning may be better exploited if aerobic exercise is paired more closely in time with motor training. Additionally, information about BDNF genotype could provide insight into the type and magnitude of effects that aerobic exercise may have across individuals and potentially help guide an individualized prescription of aerobic exercise to enhance motor rehabilitation poststroke.
Diabetes is associated with a loss of somatosensory and motor function, leading to impairments in gait, balance, and manual dexterity. Data-driven neuroimaging studies frequently report a negative ...impact of diabetes on sensorimotor regions in the brain; however, relationships with sensorimotor behavior are rarely considered. The goal of this review is to consider existing diabetes neuroimaging evidence through the lens of sensorimotor neuroscience. We review evidence for diabetes-related disruptions to three critical circuits for movement control: the cerebral cortex, the cerebellum, and the basal ganglia. In addition, we discuss how central nervous system (CNS) degeneration might interact with the loss of sensory feedback from the limbs due to peripheral neuropathy to result in motor impairments in individuals with diabetes. We argue that our understanding of movement impairments in individuals with diabetes is incomplete without the consideration of disease complications in both the central and peripheral nervous systems. Neuroimaging evidence for disrupted central sensorimotor circuitry suggests that there may be unrecognized behavioral impairments in individuals with diabetes. Applying knowledge from the existing literature on CNS contributions to motor control and motor learning in healthy individuals provides a framework for hypothesis generation for future research on this topic.
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