scholarly journals The effect of breaking up prolonged sitting on paired associative stimulation-induced plasticity

2020 ◽  
Vol 238 (11) ◽  
pp. 2497-2506 ◽  
Author(s):  
E. Bojsen-Møller ◽  
M. M. Ekblom ◽  
O. Tarassova ◽  
D. W. Dunstan ◽  
O. Ekblom
Keyword(s):  
Physical Activity ◽  
Motor Cortex ◽  
Fixed Effects ◽  
Primary Motor Cortex ◽  
Short Interval ◽  
Moderate Intensity ◽  
Middle Aged ◽  
Moderate Intensity Exercise ◽  
Abductor Pollicis Brevis ◽  
Paired Associative Stimulation

Abstract Paired associative stimulation (PAS) can induce plasticity in the motor cortex, as measured by changes in corticospinal excitability (CSE). This effect is attenuated in older and less active individuals. Although a single bout of exercise enhances PAS-induced plasticity in young, physically inactive adults, it is not yet known if physical activity interventions affect PAS-induced neuroplasticity in middle-aged inactive individuals. Sixteen inactive middle-aged office workers participated in a randomized cross-over design investigating how CSE and short-interval intracortical inhibition (SICI) were affected by PAS preceded by 3 h of sitting (SIT), 3 h of sitting interrupted every 30 min by 3 min of frequent short bouts of physical activity (FPA) and 2.5 h of sitting followed by 25 min of moderate-intensity exercise (EXE). Transcranial magnetic stimulation was applied over the primary motor cortex (M1) of the dominant abductor pollicis brevis to induce recruitment curves before and 5 min and 30 min post-PAS. Linear mixed models were used to compare changes in CSE using time and condition as fixed effects and subjects as random effects. There was a main effect of time on CSE and planned within-condition comparisons showed that CSE was significantly increased from baseline to 5 min and 30 min post-PAS, in the FPA condition, with no significant changes in the SIT or EXE conditions. SICI decreased from baseline to 5 min post-PAS, but this was not related to changes in CSE. Our findings suggest that in middle-aged inactive adults, FPAs may promote corticospinal neuroplasticity. Possible mechanisms are discussed.

scholarly journals Modulation of motor cortex inhibition during motor imagery

2017 ◽  
Vol 117 (4) ◽  
pp. 1776-1784 ◽  
Author(s):  
Benjamin W. X. Chong ◽  
Cathy M. Stinear
Keyword(s):  
Motor Cortex ◽  
Motor Imagery ◽  
Primary Motor Cortex ◽  
Muscle Relaxation ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Abductor Pollicis Brevis ◽  
Voluntary Muscle ◽  
Abductor Digiti Minimi

Motor imagery (MI) is similar to overt movement, engaging common neural substrates and facilitating the corticomotor pathway; however, it does not result in excitatory descending motor output. Transcranial magnetic stimulation (TMS) can be used to assess inhibitory networks in the primary motor cortex via measures of 1-ms short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI), and late cortical disinhibition (LCD). These measures are thought to reflect extrasynaptic GABAA tonic inhibition, postsynaptic GABAB inhibition, and presynaptic GABAB disinhibition, respectively. The behavior of 1-ms SICI, LICI, and LCD during MI has not yet been explored. This study aimed to investigate how 1-ms SICI, LICI, and LCD are modulated during MI and voluntary relaxation (VR) of a target muscle. Twenty-five healthy young adults participated. TMS was used to assess nonconditioned motor evoked potential (MEP) amplitude, 1-ms SICI, 100- (LICI100) and 150-ms LICI, and LCD in the right abductor pollicis brevis (APB) and right abductor digiti minimi during rest, MI, and VR of the hand. Compared with rest, MEP amplitudes were facilitated in APB during MI. SICI was not affected by task or muscle. LICI100 decreased in both muscles during VR but not MI, whereas LCD was recruited in both muscles during both tasks. This indicates that VR modulates postsynaptic GABAB inhibition, whereas both tasks modulate presynaptic GABAB inhibition in a non-muscle-specific way. This study highlights further neurophysiological parallels between actual and imagined movement, which may extend to voluntary relaxation. NEW & NOTEWORTHY This is the first study to investigate how 1-ms short-interval intracortical inhibition, long-interval intracortical inhibition, and late cortical disinhibition are modulated during motor imagery and voluntary muscle relaxation. We present novel findings of decreased 100-ms long-interval intracortical inhibition during voluntary muscle relaxation and increased late cortical disinhibition during both motor imagery and voluntary muscle relaxation.

scholarly journals The AgingPLUS Trial: Intervening to Promote Physical Activity in Middle-Aged and Older Adults

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 435-435
Author(s):  
David Roth ◽  
Shang-En (Michelle) Chung ◽  
Kaigang Li ◽  
Abigail Nehrkorn-Bailey ◽  
Katherine Thompson ◽  
...  
Keyword(s):  
Physical Activity ◽  
Older Adults ◽  
Physical Function ◽  
Motivational Factors ◽  
Moderate Intensity ◽  
Middle Aged ◽  
Moderate Intensity Exercise ◽  
Intervention Effects ◽  
Standardized Effect Sizes ◽  
Mediational Role

Abstract This paper investigated whether the AgingPLUS program promotes physical activity in middle-aged and older adults by examining outcomes at weeks 4 and 8 with baseline scores included as covariates. The analyses assessed intervention effects on negative views of aging (NVOA), physical activity (CHAMPS), physical function (SPPB, VO2max), and accelerometry measures (e.g., minutes sedentary). We found significant intervention effects on NVOA (p < .001) and frequency of moderate intensity exercise (p = 0.048), but no significant effects on physical function, VO2max, or the accelerometry measures. Standardized effect sizes for the significant effects ranged from 0.31 to 1.03 standard deviation units. These findings suggest that AgingPLUS improved motivational factors for engaging in physical activity but did not lead to objective changes in physical activity in the short term. Further research will investigate the mediational role of these motivational factors in enhancing physical activity over the longer term (6 months).

scholarly journals Frontal and motor cortex oxygenation during maximal exercise in normoxia and hypoxia

2009 ◽  
Vol 106 (4) ◽  
pp. 1153-1158 ◽  
Author(s):  
Andrew W. Subudhi ◽  
Brittany R. Miramon ◽  
Matthew E. Granger ◽  
Robert C. Roach
Keyword(s):  
Motor Cortex ◽  
Near Infrared ◽  
Maximal Exercise ◽  
Acute Hypoxia ◽  
Moderate Intensity ◽  
Chamber Pressure ◽  
Motor Drive ◽  
Maximal Power ◽  
Moderate Intensity Exercise ◽  
Test Order

Reductions in prefrontal oxygenation near maximal exertion may limit exercise performance by impairing executive functions that influence the decision to stop exercising; however, whether deoxygenation also occurs in motor regions that more directly affect central motor drive is unknown. Multichannel near-infrared spectroscopy was used to compare changes in prefrontal, premotor, and motor cortices during exhaustive exercise. Twenty-three subjects performed two sequential, incremental cycle tests (25 W/min ramp) during acute hypoxia [79 Torr inspired Po2 (PiO2)] and normoxia (117 Torr PiO2) in an environmental chamber. Test order was balanced, and subjects were blinded to chamber pressure. In normoxia, bilateral prefrontal oxygenation was maintained during low- and moderate-intensity exercise but dropped 9.0 ± 10.7% (mean ± SD, P < 0.05) before exhaustion (maximal power = 305 ± 52 W). The pattern and magnitude of deoxygenation were similar in prefrontal, premotor, and motor regions ( R2 > 0.94). In hypoxia, prefrontal oxygenation was reduced 11.1 ± 14.3% at rest ( P < 0.01) and fell another 26.5 ± 19.5% ( P < 0.01) at exhaustion (maximal power = 256 ± 38 W, P < 0.01). Correlations between regions were high ( R2 > 0.61), but deoxygenation was greater in prefrontal than premotor and motor regions ( P < 0.05). Prefrontal, premotor, and motor cortex deoxygenation during high-intensity exercise may contribute to an integrative decision to stop exercise. The accelerated rate of cortical deoxygenation in hypoxia may hasten this effect.

Reversal of Cortical Reorganization in Human Primary Motor Cortex Following Thumb Reconstruction

2010 ◽  
Vol 103 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Zhen Ni ◽  
Dimitri J. Anastakis ◽  
Carolyn Gunraj ◽  
Robert Chen
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Short Interval ◽  
Body Part ◽  
Cortical Reorganization ◽  
Traumatic Amputation ◽  
Motor Threshold ◽  
Thumb Reconstruction ◽  
Intact Side ◽  
Injured Side

Deafferentation such as the amputation of a body part causes cortical reorganization in the primary motor cortex (M1). We investigated whether this reorganization is reversible after reconstruction of the lost body part. We tested two patients who had long-standing thumb amputations followed by thumb reconstruction with toe-to-thumb transfer 9 to 10 mo later and one patient who underwent thumb replantation immediately following traumatic amputation. Using transcranial magnetic stimulation, we measured the motor evoked potential (MEP) threshold, latency, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) at different time points in the course of recovery in abductor pollicis brevis muscle. For the two patients who underwent late toe-to-thumb transfer, the rest motor threshold was lower on the injured side than that on the intact side before surgery and it increased with time after reconstruction, whereas the active motor threshold remained unchanged. The rest and active MEP latencies were similar on the injured side before and ≤15 wk after surgery and followed by restoration of expected latency differences. SICI was reduced before surgery and progressively normalized with the time after surgery. ICF did not change with time. These physiological measures correlated with the recovery of motor and sensory functions. All the measurements on the intact side of the toe-to-thumb transfer patients and in the patient with thumb replantation immediately following traumatic amputation remained stable over time. We conclude that chronic reorganization occurring in the M1 after amputation can be reversed by reconstruction of the lost body part.

scholarly journals The Regulation of the Metastatic Cascade by Physical Activity: A Narrative Review

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 153 ◽  
Author(s):  
Sophie van Doorslaer de ten Ryen ◽  
Louise Deldicque
Keyword(s):  
Physical Activity ◽  
Careful Analysis ◽  
The Body ◽  
Narrative Review ◽  
Moderate Intensity ◽  
Moderate Physical Activity ◽  
Moderate Intensity Exercise ◽  
Tumor Spread ◽  
Warm Up ◽  
Cancer Dissemination

The purpose of this narrative review is to provide an overview of the currently available knowledge about the mechanisms by which physical activity may affect metastatic development. The search terms exercise [Title/Abstract] AND metastasis [Title/Abstract] returned 222 articles on PUBMED on the 10 February 2019. After careful analysis of the abstracts, a final selection of 24 articles was made. Physical activity regulates the levels of metastatic factors in each of the five steps of the process. Moderate intensity exercise appears to prevent tumor spread around the body, among others, by normalizing angiogenesis, destroying circulating tumor cells, and decreasing endothelial cells permeability. Contrarily, high-intensity exercise seems to favor cancer dissemination, likely through excessive stress, which can be somewhat counteracted by an appropriate warm-up. In conclusion, chronic adaptations to moderate-intensity endurance exercise seem the most effective way to achieve a preventive effect of exercise on metastases. Altogether, the data gathered here reinforce the importance of encouraging cancer patients to perform moderate physical activity several times a week. To limit the undesired events thereof, a good knowledge of the patient’s training level is important to establish an adapted exercise training program.

scholarly journals Priming Effects of Water Immersion on Paired Associative Stimulation-Induced Neural Plasticity in the Primary Motor Cortex

2019 ◽  
Vol 17 (1) ◽  
pp. 215 ◽  
Author(s):  
Daisuke Sato ◽  
Koya Yamashiro ◽  
Yudai Yamazaki ◽  
Koyuki Ikarashi ◽  
Hideaki Onishi ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Primary Motor Cortex ◽  
Water Immersion ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Long Term Potentiation ◽  
Cortical Inhibition ◽  
Stimulus Interval ◽  
Paired Associative Stimulation ◽  
Inter Stimulus Interval

We aimed to verify whether indirect-wave (I-wave) recruitment and cortical inhibition can regulate or predict the plastic response to paired associative stimulation with an inter-stimulus interval of 25 ms (PAS25), and also whether water immersion (WI) can facilitate the subsequent PAS25-induced plasticity. To address the first question, we applied transcranial magnetic stimulation (TMS) to the M1 hand area, while alternating the direction of the induced current between posterior-to-anterior and anterior-to-posterior to activate two independent synaptic inputs to the corticospinal neurons. Moreover, we used a paired stimulation paradigm to evaluate the short-latency afferent inhibition (SAI) and short-interval intracortical inhibition (SICI). To address the second question, we examined the motor evoked potential (MEP) amplitudes before and after PAS25, with and without WI, and used the SAI, SICI, and MEP recruitment curves to determine the mechanism underlying priming by WI on PAS25. We demonstrated that SAI, with an inter-stimulus interval of 25 ms, might serve as a predictor of the response to PAS25, whereas I-wave recruitment evaluated by the MEP latency difference was not predictive of the PAS25 response, and found that 15 min WI prior to PAS25 facilitated long-term potentiation (LTP)-like plasticity due to a homeostatic increase in cholinergic activity.

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