scholarly journals Fatigue induces behavioural improvements in the unfatigued hand via altered functional connectivity and neurochemicals in cortical motor areas

2021 ◽  
Author(s):  
Justin W Andrushko ◽  
Jacob M Levenstein ◽  
Catharina Zich ◽  
Evan C Edmond ◽  
Jon Campbell ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Motor Performance ◽  
Primary Motor Cortex ◽  
Maximum Voluntary Contraction ◽  
Reaction Time Task ◽  
Voluntary Contraction ◽  
Sensorimotor Network ◽  
Before And After ◽  
Contralateral Hand ◽  
Fatiguing Exercise

In humans, motor learning is underpinned by changes in functional connectivity (FC) across the sensorimotor network. Unilateral exercise-induced fatigue increases FC in the ipsilateral primary motor cortex (M1) and supplementary motor area (SMA); areas involved in motor planning and execution of the contralateral hand. Unilateral fatiguing exercise is therefore a promising potential approach to augment motor performance in the non-fatigued, contralateral, hand. In a within-participant, controlled, randomized, cross-over design, 15 right-handed adults had two magnetic resonance imaging (MRI) sessions, where functional MRI and MR Spectroscopic Imaging were acquired before and after repeated right-hand contractions at either 5% or 50% maximum voluntary contraction (MVC). Before and after scanning, response times (RTs) were determined in both hands, and after scanning, participants performed a serial reaction time task (SRTT) with their left, unfatigued, hand. Nine minutes of 50% MVC contractions resulted in fatigue. This unimanual fatigue improved motor performance, as indexed by decreased RTs, in the contralateral hand. Although fatigue had no significant effects on sequence learning, fatigue led to a significant increase in the transfer of the learned skill to the untrained hand. These behavioural effects were supported by significant neural changes: an increase in SMA-SMA functional connectivity, and increased connectivity between right M1 and right Orbitofrontal Cortex. At a neurochemical level, the degree of fatigue-induced decrease in GABA in left M1, left and right SMA correlated with subsequent behavioural improvements in the left-hand. These results support unilateral fatiguing exercise as a potential therapeutic intervention in a range of neurological and orthopedic conditions.

scholarly journals Strengthened Corticosubcortical Functional Connectivity during Muscle Fatigue

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Zhiguo Jiang ◽  
Xiao-Feng Wang ◽  
Guang H. Yue
Keyword(s):  
Motor Control ◽  
Functional Connectivity ◽  
Quantile Regression ◽  
Muscle Fatigue ◽  
Motor Performance ◽  
Primary Motor Cortex ◽  
Motor Task ◽  
Voluntary Contraction ◽  
Control Network ◽  
Subcortical Structures

The present study examined functional connectivity (FC) between functional MRI (fMRI) signals of the primary motor cortex (M1) and each of the three subcortical neural structures, cerebellum (CB), basal ganglia (BG), and thalamus (TL), during muscle fatigue using the quantile regression technique. Understanding activation relation between the subcortical structures and the M1 during prolonged motor performance should help delineate how central motor control network modulates acute perturbations at peripheral sensorimotor system such as muscle fatigue. Ten healthy subjects participated in the study and completed a 20-minute intermittent handgrip motor task at 50% of their maximal voluntary contraction (MVC) level. Quantile regression analyses were carried out to compare the FC between the contralateral (left) M1 and CB, BG, and TL in the minimal (beginning 100 s) versus significant (ending 100 s) fatigue stages. Widespread, statistically significant increases in FC were found in bilateral BG, CB, and TL with the left M1 during significant versus minimal fatigue stages. Our results imply that these subcortical nuclei are critical components in the motor control network and actively involved in modulating voluntary muscle fatigue, possibly, by working together with the M1 to strengthen the descending central command to prolong the motor performance.

scholarly journals Longitudinal Brain Functional Connectivity Changes of the Cortical Motor-Related Network in Subcortical Stroke Patients with Acupuncture Treatment

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yongxin Li ◽  
Ya Wang ◽  
Chenxi Liao ◽  
Wenhua Huang ◽  
Ping Wu
Keyword(s):  
Functional Connectivity ◽  
Western Medicine ◽  
Primary Motor Cortex ◽  
Brain Connectivity ◽  
Effective Means ◽  
Brain Network ◽  
Stroke Patients ◽  
Rehabilitation Therapy ◽  
Cortical Motor ◽  
Before And After

In clinical practice, the effectiveness of the rehabilitation therapy such as acupuncture combining conventional Western medicine (AG) on stroke people’s motor-related brain network and their behaviors has not been systematically studied. In the present study, seventeen adult ischemic patients were collected and divided into two groups: the conventional Western medicine treatment group (CG) and the AG. The neurological deficit scores (NDS) and resting-state functional MRI data were collected before and after treatment. Compared with the CG patients, AG patients exhibited a significant enhancement of the percent changes of NDS from pre- to posttreatment intervention. All patients showed significant changes of functional connectivity (FC) between the pair of cortical motor-related regions. After treatment, both patient groups showed a recovery of brain connectivity to the nearly normal level compared with the controls in these pairs. Moreover, a significant correlation between the percent changes of NDS and the pretreatment FC values of bilateral primary motor cortex (M1) in all patients was found. In conclusion, our results showed that AG therapy can be an effective means for ischemic stroke patients to recover their motor function ability. The FC strengths between bilateral M1 of stroke patients can predict stroke patients’ treatment outcome after rehabilitation therapy.

The strength of the corticospinal coherence depends on the predictability of modulated isometric forces

2013 ◽  
Vol 109 (6) ◽  
pp. 1579-1588 ◽  
Author(s):  
Ignacio Mendez-Balbuena ◽  
Jose Raul Naranjo ◽  
Xi Wang ◽  
Agnieska Andrykiewicz ◽  
Frank Huethe ◽  
...  
Keyword(s):  
Sensory Feedback ◽  
Muscle Activation ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Visuomotor Task ◽  
Gamma Range ◽  
Cortical Motor ◽  
Contralateral Hand ◽  
Hand Motor Area ◽  
Isometric Forces

Isometric compensation of predictably frequency-modulated low forces is associated with corticomuscular coherence (CMC) in beta and low gamma range. It remains unclear how the CMC is influenced by unpredictably modulated forces, which create a mismatch between expected and actual sensory feedback. We recorded electroencephalography from the contralateral hand motor area, electromyography (EMG), and the motor performance of 16 subjects during a visuomotor task in which they had to isometrically compensate target forces at 8% of the maximum voluntary contraction with their right index finger. The modulated forces were presented with predictable or unpredictable frequencies. We calculated the CMC, the cortical motor alpha-, beta-, and gamma-range spectral powers (SP), and the task-related desynchronization (TRD), as well as the EMG SP and the performance. We found that in the unpredictable condition the CMC was significantly lower and associated with lower cortical motor SP, stronger TRD, higher EMG SP, and worse performance. The findings suggest that due to the mismatch between predicted and actual sensory feedback leading to higher computational load and less stationary motor state, the unpredictable modulation of the force leads to a decrease in corticospinal synchrony, an increase in cortical and muscle activation, and a worse performance.

FORCE SUMMATION AND TWITCH POTENTIATION CAPACITY IN HUMAN ANKLE PLANTAR- AND DORSI-FLEXOR MUSCLES

2014 ◽  
Vol 17 (04) ◽  
pp. 1450015
Author(s):  
Yoichi Ohta ◽  
Kengo Yotani
Keyword(s):  
Muscle Function ◽  
Pulse Train ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Twitch Potentiation ◽  
Flexor Muscles ◽  
Human Ankle ◽  
Before And After ◽  
Isometric Torque ◽  
Plantar Flexor Muscles

Purpose: The present study aimed to clarify inter-individual correlation between the magnitudes of force summation and the post-activation potentiation (PAP), in human ankle plantar- and dorsi-flexor muscles. Methods: We analyzed 10 male participants plantar-flexor muscles and the 12 male participants dorsi-flexor muscles using a database from a previous study. Before and after maximum voluntary contraction, we measured the amount of isometric torque evoked by a single, double- and triple-pulse train stimulus. Results: The magnitude of PAP was significantly positively correlated with the magnitude of force summation in both the plantar- and dorsi-flexor muscles. Conclusions: The present study confirmed the correlation between the magnitudes of force summation and PAP in human ankle plantar- and dorsi-flexor muscles. This suggests that muscle characteristics affecting the force summation capacity depend on the PAP, to some degree. These results suggest that the combination of both parameters might enhance the usefulness of evaluating changes in muscle function using intrinsic contractile properties.

scholarly journals Motor planning perturbation: muscle activation and reaction time

2018 ◽  
Vol 120 (4) ◽  
pp. 2059-2065
Author(s):  
Stefan Delmas ◽  
Agostina Casamento-Moran ◽  
Seoung Hoon Park ◽  
Basma Yacoubi ◽  
Evangelos A. Christou
Keyword(s):  
Reaction Time ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Maximum Voluntary Contraction ◽  
Motor Planning ◽  
Reaction Time Task ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Time Interval ◽  
Voluntary Activity

Reaction time (RT) is the time interval between the appearance of a stimulus and initiation of a motor response. Within RT, two processes occur, selection of motor goals and motor planning. An unresolved question is whether perturbation to the motor planning component of RT slows the response and alters the voluntary activation of muscle. The purpose of this study was to determine how the modulation of muscle activity during an RT response changes with motor plan perturbation. Twenty-four young adults (20.5 ±1.1 yr, 13 women) performed 15 trials of an isometric RT task with ankle dorsiflexion using a sinusoidal anticipatory strategy (10–20% maximum voluntary contraction). We compared the processing part of the RT and modulation of muscle activity from 10 to 60 Hz of the tibialis anterior (primary agonist) when the stimulus appeared at the trough or at the peak of the sinusoidal task. We found that RT ( P = 0.003) was longer when the stimulus occurred at the peak compared with the trough. During the time of the reaction, the electromyography (EMG) power from 10 to 35 Hz was less at the peak than the trough ( P = 0.019), whereas the EMG power from 35 to 60 Hz was similar between the peak and trough ( P = 0.92). These results suggest that perturbation to motor planning lengthens the processing part of RT and alters the voluntary activation of the muscle by decreasing the relative amount of power from 10 to 35 Hz. NEW & NOTEWORTHY We aimed to determine whether perturbation to motor planning would alter the speed and muscle activity of the response. We compared trials when a stimulus appeared at the peak or trough of an oscillatory reaction time task. When the stimulus occurred at the trough, participants responded faster, with greater force, and less EMG power from 10-35 Hz. We provide evidence that motor planning perturbation slows the response and alters the voluntary activity of the muscle.

Effect of Social Stress on Motor Function in Older Adults: an fNIRS Investigation

2017 ◽  
Vol 61 (1) ◽  
pp. 31-31
Author(s):  
Joohyun Rhee ◽  
Taylor Dillards ◽  
Michelle Nzoiwu ◽  
Ranjana K. Mehta
Keyword(s):  
Older Adults ◽  
Stress Level ◽  
Social Stress ◽  
Motor Performance ◽  
Memory Function ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Neural Activation ◽  
Force Steadiness ◽  
Before And After

Stress has adverse impacts on mental and physical health and quality of life, especially in older adults. Stress can impair cognitive function including short and long-term memory, and this functional declines can further be associated with decreased neuromuscular performance (Mehta & Parasuraman, 2014) and increased fatigability (Keller-Ross et al., 2014). Since older adults are more susceptible to the effect of stress because their limited mobility caused by aging can worsen under stress (Noven at al., 2014), it is important to examine the effect of acute stress on neuromuscular function in older adults. In the present study, we tested the effect of social stress on neuromuscular function of both upper and lower extremity in older adults before and after a short bout of social stress. Thirty participants (15 males, 15 females, mean age: 73.3 (5.6) yrs) performed ten trials of submaximal voluntary contraction at 30% of their maximum voluntary contraction force level before and after the Trier Social Stress Test (TSST) session. Handgrip and knee extension motor performance was measured on separate days. TSST consisted of five minutes speech and five minutes serial arithmetic subtraction tasks. We measured force steadiness and electromyography (EMG) of working muscles to evaluate motor function. Additionally, electrocardiogram (ECG), the Visual Analogue Scale of Stress (VAS), and salivary cortisol were collected to evaluate the effect of the TSST. Neural activation pattern changes of prefrontal and sensorimotor area during exercise and TSST sessions was recorded using functional Near Infrared Spectroscopy (fNIRS). To confirm whether the TSST session increased stress level in our participants, we first analysed the stress metrics. Heart rate increased during the TSST and returned to prestress level instantly after the TSST session. Perceived stress level using the VAS increased after TSST. While not significant, salivary cortisol level increased after the TSST session. Findings indicate that handgrip force steadiness improved after the TSST session, whereas knee extension force steadiness remained unchanged. On the other hand, handgrip EMG root mean square (RMS) did not change after stress while knee extension EMG RMS was found to increase. Neural activation during handgrip exercise increased at the left motor area, and neural activation during knee extension increased at the left sensory area after the TSST session. Change of heart rate and VAS indicates that participants’ stress level was increased after stress and the improved motor performance during handgrip exercise after the stress is consistent with a previous study that reported increased memory function after stress in older adults (Pulopulos et al., 2015). However, the differential effects of stress based on upper or lower extremity indicates increased sensitivity of certain motor tasks to social stress than other. While social stress is known to affect response time but not memory function (Guez et al., 2016), different spatial activation pattern between handgrip and knee extension exercises observed in the present study suggest that different neural strategies were adapted to compensate for the effects of acute social stress to maintain motor performance.

Achilles Tendon Mechanical Properties After Both Prolonged Continuous Running and Prolonged Intermittent Shuttle Running in Cricket Batting

2013 ◽  
Vol 29 (4) ◽  
pp. 453-462 ◽  
Author(s):  
Laurence Houghton ◽  
Brian Dawson ◽  
Jonas Rubenson
Keyword(s):  
Achilles Tendon ◽  
Elastic Energy ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Force Transmission ◽  
Before And After ◽  
Tendon Force ◽  
Force Displacement ◽  
Tendon Properties

Effects of prolonged running on Achilles tendon properties were assessed after a 60 min treadmill run and 140 min intermittent shuttle running (simulated cricket batting innings). Before and after exercise, 11 participants performed ramp-up plantar flexions to maximum-voluntary-contraction before gradual relaxation. Muscle-tendon-junction displacement was measured with ultrasonography. Tendon force was estimated using dynamometry and a musculoskeletal model. Gradients of the ramp-up force-displacement curves fitted between 0–40% and 50–90% of the preexercise maximal force determined stiffness in the low- and high-force-range, respectively. Hysteresis was determined using the ramp-up and relaxation force-displacement curves and elastic energy storage from the area under the ramp-up curve. In simulated batting, correlations between tendon properties and shuttle times were also assessed. After both protocols, Achilles tendon force decreased (4% to 5%,P< .050), but there were no changes in stiffness, hysteresis, or elastic energy. In simulated batting, Achilles tendon force and stiffness were both correlated to mean turn and mean sprint times (r= −0.719 to −0.830,P< .050). Neither protocol resulted in fatigue-related changes in tendon properties, but higher tendon stiffness and plantar flexion force were related to faster turn and sprint times, possibly by improving force transmission and control of movement when decelerating and accelerating.

Task-Dependent Modulation of Inputs to Proximal Upper Limb Following Transcranial Direct Current Stimulation of Primary Motor Cortex

2010 ◽  
Vol 103 (5) ◽  
pp. 2382-2389 ◽  
Author(s):  
Lynley V. Bradnam ◽  
Cathy M. Stinear ◽  
Gwyn N. Lewis ◽  
Winston D. Byblow
Keyword(s):  
Motor Cortex ◽  
Upper Limb ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Hand Muscles ◽  
Before And After ◽  
Contralateral Hand ◽  
Left And Right ◽  
Period Duration

Cathodal transcranial DC stimulation (c-tDCS) suppresses excitability of primary motor cortex (M1) controlling contralateral hand muscles. This study assessed whether c-tDCS would have similar effects on ipsi- and contralateral M1 projections to a proximal upper limb muscle. Transcranial magnetic stimulation (TMS) of left M1 was used to elicit motor evoked potentials (MEPs) in the left and right infraspinatus (INF) muscle immediately before and after c-tDCS of left M1, and at 20 and 40 min, post-c-tDCS. TMS was delivered as participants preactivated each INF in isolation (left, right) or both INF together (bilateral). After c-tDCS, ipsilateral MEPs in left INF and contralateral MEPs in right INF were suppressed in the left task but not in the bilateral or right tasks, indicative of task-dependent modulation. Ipsilateral silent period duration in the left INF was reduced after c-tDCS, indicative of altered transcallosal inhibition. These findings may have implications for the use of tDCS as an adjunct to therapy for the proximal upper limb after stroke.

Fatigue in multiple sclerosis: The contribution of resting-state functional connectivity reorganization

2017 ◽  
Vol 24 (13) ◽  
pp. 1696-1705 ◽  
Author(s):  
Alvino Bisecco ◽  
Federica Di Nardo ◽  
Renato Docimo ◽  
Giuseppina Caiazzo ◽  
Alessandro d’Ambrosio ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Regression Analysis ◽  
Functional Connectivity ◽  
Motor Cortex ◽  
Resting State ◽  
Primary Motor Cortex ◽  
Linear Regression Analysis ◽  
Posterior Cingulate Cortex ◽  
Resting State Functional Connectivity ◽  
Sensorimotor Network

Objectives: To investigate resting-state functional connectivity (RS-FC) of the default-mode network (DMN) and of sensorimotor network (SMN) network in relapsing remitting (RR) multiple sclerosis (MS) patients with fatigue (F) and without fatigue(NF). Methods: In all, 59 RRMS patients and 29 healthy controls (HC) underwent magnetic resonance imaging (MRI) protocol including resting-state fMRI (RS-fMRI). Functional connectivity of the DMN and SMN was evaluated by independent component analysis (ICA). A linear regression analysis was performed to explore whether fatigue was mainly driven by changes observed in the DMN or in the SMN. Regional gray matter atrophy was assessed by voxel-based morphometry (VBM). Results: Compared to HC, F-MS patients showed a stronger RS-FC in the posterior cingulate cortex (PCC) and a reduced RS-FC in the anterior cingulated cortex (ACC) of the DMN. F-MS patients, compared to NF-MS patients, revealed (1) an increased RS-FC in the PCC and a reduced RS-FC in the ACC of the DMN and (2) an increased RS-FC in the primary motor cortex and in the supplementary motor cortex of the SMN. The regression analysis suggested that fatigue is mainly driven by RS-FC changes of the DMN. Conclusions: Fatigue in RRMS is mainly associated to a functional rearrangement of non-motor RS networks.

scholarly journals Pallidotomy Increases Cortical Inhibition in Parkinson's Disease

1997 ◽  
Vol 24 (2) ◽  
pp. 133-136 ◽  
Author(s):  
A. Strafella ◽  
P. Ashby ◽  
A. Lozano ◽  
A.E. Lang
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Magnetic Stimulation ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Short Latency ◽  
Cortical Inhibition ◽  
First Dorsal Interosseus ◽  
Before And After ◽  
Posteroventral Pallidotomy

ABSTRACT:Background:Pallidotomy helps parkinsonian symptoms. We tested the hypothesis that this might be due to changes in inhibition in the motor cortex.Methods:We examined 15 patients with parkinsonism before and after posteroventral pallidotomy. Magnetic stimuli were delivered over the motor cortex, while subjects maintained a 30% maximum voluntary contraction of the contralateral first dorsal interosseus (FDI).Results:Weak stimuli inhibited voluntary muscle activity, while slightly stronger stimuli caused short latency facilitation from activation of the corticospinal neurons. After pallidotomy magnetic stimulation, at the threshold for the short latency facilitation, resulted in more inhibition than before.Conclusions:Pallidotomy increases cortical inhibition. This may be associated with improved control of movements.

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