Supporting data: D2 receptor blockade eliminates exercise-induced changes in cortical inhibition and excitation

This data was acquired from an experiment in which measures of synaptic excitatory and inhibitory activity of the primary motor cortex were taken using transcranial magnetic stimulation (TMS), both before and after a 20-minute bout of high-intensity interval cycling exercise. We then examined the effect of D2 receptor blockade (800mg sulpiride) on these measures within a randomised, double-blind, placebo-controlled, crossover design. </p

The effects of dopamine and ageing on exercise-enhanced neuroplasticity

This thesis is inspired by evidence showing the benefits of exercise for the brain in healthy ageing and Parkinson’s disease — a disorder involving the loss of dopamine, a chemical messenger in the brain. The main finding was that brain activity and function, including the ability to learn a new skill, was strongly reduced when dopamine activity was blocked. Additionally, it was shown that the brain’s response to exercise is attenuated in older age. Together, these results explain how the states of low dopamine (e.g. as seen in Parkinson’s patients off their medication) and older age (> 65 years) weaken the effects of exercise on the brain

D2 receptor blockade eliminates exercise-induced changes in cortical inhibition and excitation

Background: Although cardiorespiratory exercise is known to affect cortical excitatory and inhibitory activity, the neurochemical mechanisms driving this effect are poorly understood. Animal models of Parkinson's disease identify dopamine D2 receptor expression as a candidate mechanism, but the link between the D2 receptor and exercise-induced changes in cortical activity in humans is unknown. Objective: Here, we examined the effect of a selective dopamine D2 receptor antagonist, sulpiride, on exercise-induced changes in cortical activity. Methods: We acquired measures of excitatory and inhibitory activity of the primary motor cortex using transcranial magnetic stimulation (TMS) from 23 healthy adults, both before and after a 20-min bout of high-intensity interval cycling exercise. We examined the effect of D2 receptor blockade (800 mg sulpiride) on these measures within a randomised, double-blind, placebo-controlled crossover design. Results: Sulpiride abolished exercise-induced modulation of the cortical excitation:inhibition balance relative to placebo (P < 0.001, Cohen's d = 1.76). Sulpiride blocked both the increase in glutamatergic excitation and reduction in gamma-aminobutyric acid (GABA) inhibition that was observed following exercise in the placebo condition. Conclusion: Our results provide causal evidence that D2 receptor blockade eliminates exercise-induced changes in excitatory and inhibitory cortical networks, and have implications for how exercise should be prescribed in diseases of dopaminergic dysfunction

Intensity matters: high-intensity interval exercise enhances motor cortex plasticity more than moderate exercise

A single bout of cardiovascular exercise can enhance plasticity in human cortex; however, the intensity required for optimal enhancement is debated. We investigated the effect of exercise intensity on motor cortex synaptic plasticity, using transcranial magnetic stimulation. Twenty healthy adults (Mage = 35.10 ± 13.25 years) completed three sessions. Measures of cortico-motor excitability (CME) and inhibition were obtained before and after a 20-min bout of either high-intensity interval exercise, moderate-intensity continuous exercise, or rest, and again after intermittent theta burst stimulation (iTBS). Results showed that high-intensity interval exercise enhanced iTBS plasticity more than rest, evidenced by increased CME and intracortical facilitation, and reduced intracortical inhibition. In comparison, the effect of moderate-intensity exercise was intermediate between high-intensity exercise and rest. Importantly, analysis of each participant's plasticity response profile indicated that high-intensity exercise increased the likelihood of a facilitatory response to iTBS. We also established that the brain-derived neurotrophic factor Val66Met polymorphism attenuated plasticity responses following high-intensity exercise. These findings suggest that high-intensity interval exercise should be considered not only when planning exercise interventions designed to enhance neuroplasticity, but also to maximize the therapeutic potential of non-invasive brain stimulation. Additionally, genetic profiling may enhance efficacy of exercise interventions for brain health

A single bout of moderate-intensity aerobic exercise improves motor learning in premanifest and early Huntington's disease

IntroductionCardiorespiratory exercise has emerged as a promising candidate to modify disease progression in Huntington's disease (HD). In animal models, exercise has been found to alter biomarkers of neuroplasticity and delay evidence of disease, and some interventions-including exercise-have shown benefits in human HD patients. In healthy human populations, increasing evidence suggests that even a single bout of exercise can improve motor learning. In this pilot study, we investigated the effect of a single bout of moderate intensity aerobic exercise on motor skill learning in presymptomatic and early manifest HD patients. MethodsParticipants were allocated to either an exercise (n = 10) or control (n = 10) group. They performed either 20 min of moderate intensity cycling or rest before practicing a novel motor task, the sequential visual isometric pinch force task (SVIPT). After 1 week, the retention of the SVIPT was measured in both groups. ResultsWe found that the exercise group performed significantly better during initial task acquisition. There were no significant differences in offline memory consolidation between groups, but total skill gain across both acquisition and retention sessions was greater in the group who exercised. The better performance of the exercise group was driven by improvements in accuracy, rather than speed. DiscussionWe have shown that a single bout of moderate intensity aerobic exercise can facilitate motor skill learning in people with HD gene-expansion. More research is needed to investigate the underlying neural mechanisms and to further explore the potential for neurocognitive and functional benefits of exercise for people with HD.ISSN:1664-107

High-intensity acute exercise impacts motor learning in healthy older adults

Abstract Healthy aging is associated with changes in motor sequence learning, with some studies indicating decline in motor skill learning in older age. Acute cardiorespiratory exercise has emerged as a potential intervention to improve motor learning, however research in healthy older adults is limited. The current study investigated the impact of high-intensity interval exercise (HIIT) on a subsequent sequential motor learning task. Twenty-four older adults (aged 55–75 years) completed either 20-minutes of cycling, or an equivalent period of active rest before practicing a sequential force grip task. Skill learning was assessed during acquisition and at a 6-hour retention test. In contrast to expectation, exercise was associated with reduced accuracy during skill acquisition compared to rest, particularly for the oldest participants. However, improvements in motor skill were retained in the exercise condition, while a reduction in skill was observed following rest. Our findings indicate that high-intensity exercise conducted immediately prior to learning a novel motor skill may have a negative impact on motor performance during learning in older adults. We also demonstrated that exercise may facilitate early offline consolidation of a motor skill within this population, which has implications for motor rehabilitation