Effects of Moderate Exercise on Cortical Resilience: A Transcranial Magnetic Stimulation Study Targeting the Dorsolateral Prefrontal Cortex

Defining the concept of reserve in the motor domain: a systematic review

A reserve in the motor domain may underlie the capacity exhibited by some patients to maintain motor functionality in the face of a certain level of disease. This form of "motor reserve" (MR) could include cortical, cerebellar, and muscular processes. However, a systematic definition has not been provided yet. Clarifying this concept in healthy individuals and patients would be crucial for implementing prevention strategies and rehabilitation protocols. Due to its wide application in the assessment of motor system functioning, non-invasive brain stimulation (NIBS) may support such definition. Here, studies focusing on reserve in the motor domain and studies using NIBS were revised. Current literature highlights the ability of the motor system to create a reserve and a possible role for NIBS. MR could include several mechanisms occurring in the brain, cerebellum, and muscles, and NIBS may support the understanding of such mechanisms.

Effects of acute aerobic exercise on food-reward mechanisms in smoking-addicted individuals: An fNIRS study

PURPOSE

In addition to its toxic effects on the human cardiovascular and respiratory systems, tobacco dependence also causes damage to brain function and cognitive activity. Therefore, the main objective of this study was to investigate the effects of acute aerobic exercise on food-reward function and its food-cued prefrontal brain activation in tobacco-dependent individuals.

METHOD

Ninety-three participants who met the study criteria were randomly divided into a moderate-intensity exercise group (65%-75% HRmax), a high-intensity exercise group (75%-85% HRmax), and a quiet control group (n = 31 in each group). Participants were asked to perform a 35-minute target-intensity exercise or rest. The participants took the Leeds Food Preference Questionnaire and the Visual Food Cues Paradigm Task immediately before the experiment and immediately after completing the exercise or control intervention, and oxyhemoglobin concentrations in each prefrontal brain region were measured at the same time as the Visual Food Cues Paradigm Task.

RESULTS

Acute aerobic exercise significantly increased implicit cravings for low-calorie sweets in nicotine-dependent individuals (high: p = 0.040; moderate: p = 0.001), while acute moderate-intensity aerobic exercise also significantly increased the activation levels of the left dorsolateral prefrontal cortex (DLPFC: CH15: p = 0.030; CH22: p = 0.003) as well as the left orbitofrontal area (OFC: CH21: p = 0.007) in the food-reward brain region in nicotine-dependent individuals.

CONCLUSION

Acute aerobic exercise improves food-reward function and effectively increases activation levels in the DLPFC and OFC cerebral cortex in tobacco-dependent individuals, facilitating restoration of sensitivity to their drug-hijacked natural reward circuits.

Promoting brain health through physical activity among adults exposed to early life adversity: Potential mechanisms and theoretical framework

Adverse childhood experiences such as abuse, neglect, and poverty, profoundly alter neurobehavioral development in a manner that negatively impacts health across the lifespan. Adults who have been exposed to such adversities exhibit premature and more severe age-related declines in brain health. Unfortunately, it remains unclear whether the negative effects of early life adversity (ELA) on brain health can be remediated through intervention in adulthood. Physical activity may represent a low-cost behavioral approach to address the long-term consequences of ELA on brain health. However, there has been limited research examining the impact of physical activity on brain health among adults with a history of ELA. Accordingly, the purpose of this review is to (1) review the influence of ELA on brain health in adulthood and (2) highlight evidence for the role of neurotrophic factors, hypothalamic-adrenal-pituitary axis regulation, inflammatory processes, and epigenetic modifications in mediating the effects of both ELA and physical activity on brain health outcomes in adulthood. We then propose a theoretical framework to guide future research in this area.

Investigating Cortical Buffering Effects of Acute Moderate Intensity Exercise: A cTBS Study Targeting the Left Dorsolateral Prefrontal Cortex

Background: The beneficial effects of both single-session bouts of aerobic exercise and therapeutic exercise interventions on the cortical regions associated with top-down attentional control [i.e., prefrontal cortex (PFC)] have been well documented. However, it remains unclear whether aerobic exercise can be used to buffer against suppressive influences on the dorsolateral PFC (dlPFC). Objective: The current study sought to determine whether a single session of moderate intensity aerobic exercise can offset the expected suppressive effects of continuous theta burst stimulation (cTBS) targeting the dorsolateral prefrontal cortex (dlPFC). Methods: Twenty-two right-handed participants (aged 19-30) completed a 20-minute movement-only control session [10% heart rate reserve (HRR)] and moderate intensity (50% HRR) exercise in a counterbalanced order. Following each exercise session, participants received active cTBS to the left dlPFC. Changes in executive functions were quantified using a Flanker paradigm employed at baseline, post-exercise and post-cTBS time points. Additionally, EEG was used to measure changes in event-related potential components related to inhibitory control (i.e., N2) and attentional control (i.e., P3) during the flanker task. Results: Behavioral results from the flanker task revealed a significant improvement in task performance following an acute bout of moderate intensity exercise. Furthermore, the effect of cTBS in both the movement-only control and moderate intensity conditions were non-significant. Similarly, EEG data from P3b and N2 ERP components revealed no changes to amplitude across time and condition. P3b latency data revealed a significant effect of time in both the moderate intensity and movement-only conditions, such that P3b latencies were significantly shorter across time points. Latency data within the N2 ERP component revealed no significant interactions or main effects. Conclusion: The findings of the current study provide tentative support for the hypothesis that both moderate and light intensity exercise promote cortical buffering against the suppressive effects of cTBS targeting the dlPFC. However, in the absence of a no-movement control, a lack of expected suppressive effects of cTBS cannot be ruled out.

Quantifying Cortical Resilience in Experimental, Clinical, and Epidemiological Studies: A Conceptually Grounded Method Using Noninvasive Brain Stimulation

OBJECTIVE

Cortical resilience can be defined as the ability of the cortex of the human brain to rebound efficiently from perturbation. This concept is important in both research and clinical practice contexts. However, no direct measure of cortical resilience exists. Inhibitory variants of repetitive transcranial magnetic stimulation, such as continuous theta burst stimulation, provide a standardized method for inducing a perturbation; when coupled with the assessment of recovery rate from the perturbation, such a paradigm might provide a standardized measure of cortical resilience. This article describes a standardized method for quantifying cortical resilience using theta burst stimulation protocols.

METHODS

A descriptive overview of a method for assessing cortical resilience is presented. Links are drawn between critical facets of the resilience construct and the protocol described.

RESULTS

The Cortical Challenge and Recovery Test (CCaRT) method makes use of existing stimulation parameters and cognitive testing paradigms to provide a flexible and conceptually meaningful measure of cortical resilience.

CONCLUSIONS

The CCaRT paradigm is potentially useful in research and contexts where cortical resilience is to be measured. The CCaRT paradigm has applicability to epidemiological studies and laboratory experimentation as well as diagnostic practice and clinical trial outcome measures.

Effects of Acute Exercise Duration on the Inhibition Aspect of Executive Function in Late Middle-Aged Adults

Objective: This study investigated whether acute exercise duration affects inhibition in late middle-aged adults. Methods: Over four separate days, 40 late middle-aged adults completed, in a counterbalanced order, three exercise sessions consisting of single bouts of moderate-to-vigorous intensity cycling, with the main acute exercise durations being 10, 20, and 45 min, and a control session consisting of 30 min of reading. Their inhibition performance was then evaluated by administration of the Stroop test following each session. Results: The participants had shorter mean response times for both the congruent and neutral conditions of the Stroop following the acute exercise lasting 20 min than they did after the control session. The acute exercise lasting 20 min also resulted in shorter response times for both conditions of the Stroop than the acute exercise lasting only 10 min. Meanwhile, the acute exercise lasting 45 min resulted in a shorter mean response time for the neutral Stroop condition than did the control session. Finally, the acute exercise lasting 20 min resulted in the shortest mean response time of all four sessions for the Stroop incongruent condition. Conclusion: The above findings suggest that the moderate-to-vigorous intensity acute exercise lasting 20 min facilitated multiple cognitive function domains in general, whereas the exercise sessions of shorter and longer duration had negligible effects on executive function in the late middle-aged adults. These results highlight the need to consider the duration of any moderate-to-vigorous intensity exercise when developing acute exercise programs to facilitate executive function in aged populations.

Exercise, spinogenesis and cognitive functions

Exercise training improves mental and cognitive functions by enhancing neurogenesis and neuroprotection. Recent studies suggest the facilitation of spinogenesis across different brain regions including hippocampus and cerebral cortex by physical activity. In this article we will summarize major findings for exercise effects on synaptogenesis and spinogenesis, in order to provide mechanisms for exercise intervention of both psychiatric diseases and neurodegenerative disorders. We will also revisit major findings for molecular mechanism governing exercise-related spinogenesis, and will discuss the screening for novel factors, or exerkines, whose levels are correlated with endurance training and affect neural plasticity. We believe that further studies focusing on the molecular mechanism of exercise-mediate spinogenesis should benefit the optimization of exercise therapy in clinics and the evaluation of treatment efficiency using specific biomarkers.

Mental health consequences of exercise withdrawal: A systematic review

OBJECTIVE

A sedentary lifestyle has been associated with mental health disorders. Many medical conditions result in the cessation of exercise, which may increase the risk of developing mental health problems. The purpose of this article is to systematically review the literature examining the effects of exercise withdrawal on mental health.

METHOD

Literature was searched using PubMed, PsycINFO, and SPORTdiscus for studies that experimentally manipulated the withdrawal of exercise and included mental health as outcome measure.

RESULTS

A total of 19 studies met inclusion criteria (total N=689 with 385 individuals participating in an exercise withdrawal condition). Exercise withdrawal consistently resulted in increases in depressive symptoms and anxiety. Other mental health outcomes were investigated infrequently. Severe mental health issues requiring clinical intervention after experimentally controlled exercise withdrawal was rare. Heterogeneity in methods and outcomes was observed, especially in terms of the duration of exercise withdrawal (range 1 to 42days, median=7days), with stronger effects if exercise withdrawal exceeded 2weeks.

CONCLUSION

Experimentally controlled exercise withdrawal has adverse consequences for mental health. These observations in healthy individuals may help to understand the onset of mental health problems in response to acute and chronic medical conditions associated with reduced physical activity. Future research is needed to investigate potential mechanisms explaining the adverse mental health consequences of cessation of exercise that will provide new targets for clinical interventions.

Role of medial premotor areas in action language processing in relation to motor skills

The literature reports that the supplementary motor area (SMA) and pre-supplementary motor area (pre-SMA) are involved in motor planning and execution, and in motor-related cognitive functions such as motor imagery. However, their specific role in action language processing remains unclear. In the present study, we investigated the impact of repetitive transcranial magnetic stimulation (rTMS) over SMA and pre-SMA during an action semantic analogy task (SAT) in relation with fine motor skills (i.e., manual dexterity) and motor imagery abilities in healthy non-expert adults. The impact of rTMS over SMA (but not pre-SMA) on reaction times (RT) during SAT was correlated with manual dexterity. Specifically, results show that rTMS over SMA modulated RT for those with lower dexterity skills. Our results therefore demonstrate a causal involvement of SMA in action language processing, as well as the existence of inter-individual differences in this involvement. We discuss these findings in light of neurolinguistic theories of language processing.

The neurocognitive consequences of sleep restriction: A meta-analytic review

The current meta-analytic review evaluated the effects of experimentally manipulated sleep restriction on neurocognitive functioning. Random-effects models were employed to estimate the overall effect size and the differential effect size across cognitive domains. Age, time of day, age-adjusted sleep deficit, cumulative days of restricted sleep, sleep latency, subjective sleepiness, and biological sex were examined as potential moderators of the effect. Based on a sample of 61 studies, from 71 different populations, findings revealed a significant negative effect of sleep restriction on cognitive processing across cognitive domains (g=-0.383, p<0.001). This effect held for executive functioning (g=-0.324, p<0.001), sustained attention (g=-0.409, p<0.001), and long-term memory (g=-0.192, p=0.002). There was insufficient evidence to detect an effect within the domains of attention, multitask, impulsive decision-making or intelligence. Age group, time of day, cumulative days of restricted sleep, sleep latency, subjective sleepiness, and biological sex were all significant moderators of the overall effect. In conclusion, the current meta-analysis is the first comprehensive review to provide evidence that short-term sleep restriction significantly impairs waking neurocognitive functioning.