Corticospinal Excitability Is Lower During Rhythmic Arm Movement Than During Tonic Contraction

2006 ◽  
Vol 95 (2) ◽  
pp. 914-921 ◽  
Author(s):  
Timothy J. Carroll ◽  
Evan R. L. Baldwin ◽  
David F. Collins ◽  
E. Paul Zehr
Keyword(s):  
Motor Cortex ◽  
Neural Control ◽  
Motor Evoked Potentials ◽  
Arm Movement ◽  
Voluntary Contraction ◽  
Tonic Contraction ◽  
H Reflex ◽  
Corticospinal Excitability ◽  
Arm Cycling ◽  
Subcortical Regions

Humans perform rhythmic, locomotor movements with the arms and legs every day. Studies using reflexes to probe the functional role of the CNS suggest that spinal circuits are an important part of the neural control system for rhythmic arm cycling and walking. Here, by studying motor-evoked potentials (MEPs) in response to transcranial magnetic stimulation (TMS) of the motor cortex, and H-reflexes induced by electrical stimulation of peripheral nerves, we show a reduction in corticospinal excitability during rhythmic arm movement compared with tonic, voluntary contraction. Responses were compared between arm cycling and tonic contraction at four positions, while participants generated similar levels of muscle activity. Both H-reflexes and MEPs were significantly smaller during arm cycling than during tonic contraction at the midpoint of arm flexion ( F = 13.51, P = 0.006; F = 11.83, P = 0.009). Subthreshold TMS significantly facilitated the FCR H-reflex during tonic contractions, but did not significantly modulate H-reflex amplitude during arm cycling. The data indicate a reduction in the responsiveness of cells constituting the fast, monosynaptic, corticospinal pathway during arm cycling and suggest that the motor cortex may contribute less to motor drive during rhythmic arm movement than during tonic, voluntary contraction. Our results are consistent with the idea that subcortical regions contribute to the control of rhythmic arm movements despite highly developed corticospinal projections to the human upper limb.

Central nervous adaptations following 1 wk of wrist and hand immobilization

2008 ◽  
Vol 105 (1) ◽  
pp. 139-151 ◽  
Author(s):  
Jesper Lundbye-Jensen ◽  
Jens Bo Nielsen
Keyword(s):  
Physical Activity ◽  
Motor Cortex ◽  
Motor Evoked Potentials ◽  
Afferent Input ◽  
Voluntary Contraction ◽  
H Reflex ◽  
Abductor Pollicis Brevis ◽  
Corticomuscular Coherence ◽  
Reduced Physical Activity ◽  
Static Contractions

Plastic neural changes have been documented in relation to different types of physical activity, but little is known about central nervous system plasticity accompanying reduced physical activity and immobilization. In the present study we investigated whether plastic neural changes occur in relation to 1 wk of immobilization of the nondominant wrist and hand and a corresponding period of recovery in 10 able-bodied volunteers. After immobilization, maximal voluntary contraction torque decreased and the variability of submaximal static contractions increased significantly without evidence of changes in muscle contractile properties. Hoffmann (H)-reflex amplitudes and the ratios of H-slope to M-slope increased significantly in flexor carpi radialis and abductor pollicis brevis at rest and during contraction without changes in corticospinal excitability, estimated from motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation. Corticomuscular coherence measures were derived from EEG and EMG obtained during static contractions. After immobilization, corticomuscular coherence in the 15- to 35-Hz range associated with maximum negative cumulant values at lags corresponding to MEP latencies decreased. One week after cast removal, all measurements returned to preimmobilization levels. The increased H-reflex amplitudes without changes in MEPs may suggest that presynaptic inhibition or postactivation depression of Ia afferents is reduced following immobilization. Reduced corticomuscular coherence may be caused by changes in afferent input at spinal and cortical levels or by changes in the descending drive from motor cortex. Further studies are needed to elucidate the mechanisms underlying the observed increased spinal excitability and reduced coupling between motor cortex and spinal motoneuronal activity following immobilization.

Premovement Changes in Corticospinal Excitability of the Biceps Brachii are Not Different Between Arm Cycling and an Intensity-Matched Tonic Contraction

Motor Control ◽  
2015 ◽  
Vol 19 (3) ◽  
pp. 223-241 ◽  
Author(s):  
David B. Copithorne ◽  
Davis A. Forman ◽  
Kevin E. Power
Keyword(s):  
Evoked Potentials ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Surface Emg ◽  
Tonic Contraction ◽  
Corticospinal Excitability ◽  
Spinal Motoneuron ◽  
Motoneuron Excitability ◽  
Arm Cycling ◽  
Motor Outputs

The purpose of this study was to determine if supraspinal and/or spinal motoneuron excitability of the biceps brachii were differentially modulated before: 1) arm cycling and 2) an intensity-matched tonic contraction. Surface EMG recordings of motor evoked potentials (MEPs) and cervicomedullary motor evoked potentials (CMEPs) were used to assess supraspinal and spinal motoneuron excitability, respectively. MEP amplitudes were larger and onset latencies shorter, before arm cycling and tonic contraction when compared with rest with no intent to move, but with no difference between motor outputs. CMEP amplitudes and onset latencies remained unchanged before cycling and tonic contraction compared with rest. Premovement enhancement of corticospinal excitability was due to an increase in supraspinal excitability that was not task-dependent. This suggests that a common neural drive is used to initiate both motor outputs with task-dependent changes in neural excitability only being evident once the motor outputs have begun.

Corticospinal excitability of the biceps brachii is higher during arm cycling than an intensity-matched tonic contraction

2014 ◽  
Vol 112 (5) ◽  
pp. 1142-1151 ◽  
Author(s):  
Davis Forman ◽  
Amita Raj ◽  
Duane C. Button ◽  
Kevin E. Power
Keyword(s):  
Evoked Potentials ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Maximum Amplitude ◽  
Elbow Flexion ◽  
Tonic Contraction ◽  
Corticospinal Excitability ◽  
Spinal Motoneuron ◽  
Motoneuron Excitability ◽  
Arm Cycling

Human studies have not assessed corticospinal excitability of an upper-limb prime mover during arm cycling. The purpose of the present study was to determine whether supraspinal and/or spinal motoneuron excitability of the biceps brachii was different between arm cycling and an intensity-matched tonic contraction. We hypothesized that spinal motoneuron excitability would be higher during arm cycling than an intensity-matched tonic contraction. Supraspinal and spinal motoneuron excitability were assessed using transcranial magnetic stimulation (TMS) of the motor cortex and transmastoid electrical stimulation (TMES) of the corticospinal tract, respectively. TMS-induced motor-evoked potentials (MEPs) and TMES-induced cervicomedullary-evoked potentials (CMEPs) were assessed at three separate positions (3, 6, and 12 o'clock relative to a clock face) during arm cycling and an intensity-matched tonic contraction. MEP amplitudes were 7.2 and 8.8% maximum amplitude of the compound muscle action potential (Mmax) larger during arm cycling compared with a tonic contraction at the 3 ( P < 0.001) and 6 o'clock ( P < 0.001) positions, respectively. There was no difference between tasks during elbow extension (12 o'clock). CMEP amplitudes were 5.2% Mmax larger during arm cycling compared with a tonic contraction at the 3 o'clock position ( P < 0.001) with no differences seen at midflexion (6 o'clock) or extension (12 o'clock). The data indicate an increase in the excitability of corticospinal neurons, which ultimately project to biceps brachii during the elbow flexion portion of arm cycling, and increased spinal motoneuron excitability at the onset of elbow flexion during arm cycling. We conclude that supraspinal and spinal motoneuron excitability are phase- and task-dependent.

Increased corticospinal excitability prior to arm cycling is due to enhanced supraspinal but not spinal motoneurone excitability

2013 ◽  
Vol 38 (11) ◽  
pp. 1154-1161 ◽  
Author(s):  
Kevin E. Power ◽  
David B. Copithorne
Keyword(s):  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Quiescent State ◽  
M Wave ◽  
Arm Cycling ◽  
Intention To Move ◽  
Stimulation Of

Human studies have not assessed supraspinal or spinal motoneurone excitability in the quiescent state prior to a rhythmic and alternating cyclical motor output. The purpose of the current study was to determine whether supraspinal and (or) spinal motoneurone excitability was modulated in humans prior to arm cycling when compared with rest with no intention to move. We hypothesized that corticospinal excitability would be enhanced prior to arm cycling due, in part, to increased spinal motoneurone excitability. Supraspinal and spinal motoneurone excitability were assessed via transcranial magnetic stimulation (TMS) of the motor cortex and transmastoid stimulation of the corticospinal tract, respectively. Surface electromyography recordings of TMS motor evoked potentials (MEPs) and cervicomedullary MEPs (CMEPs) were made from the relaxed biceps brachii muscle prior to rhythmic arm cycling and at rest with no intention to move. The amplitude of the MEPs was greater (mean increase: +9.8% of maximal M wave; p = 0.006) and their onset latencies were shorter (mean decrease: –1.5 ms; p < 0.05) prior to cycling when compared with rest. The amplitudes of the CMEPs at any of 3 stimulation intensities were not different between conditions. We conclude that premovement enhancement of corticospinal excitability is greater prior to arm cycling than at rest because of increases in supraspinal but not spinal motoneurone excitability.

scholarly journals Corticospinal excitability of the biceps brachii is shoulder position dependent

2017 ◽  
Vol 118 (6) ◽  
pp. 3242-3251 ◽  
Author(s):  
Brandon Wayne Collins ◽  
Edward W. J. Cadigan ◽  
Lucas Stefanelli ◽  
Duane C. Button
Keyword(s):  
Evoked Potentials ◽  
Maximal Voluntary Contraction ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Voluntary Contraction ◽  
Corticospinal Excitability ◽  
State Dependent ◽  
Shoulder Flexion ◽  
Erb’S Point ◽  
Shoulder Position

The purpose of this study was to examine the effect of shoulder position on corticospinal excitability (CSE) of the biceps brachii during rest and a 10% maximal voluntary contraction (MVC). Participants ( n = 9) completed two experimental sessions with four conditions: 1) rest, 0° shoulder flexion; 2) 10% MVC, 0° shoulder flexion; 3) rest, 90° shoulder flexion; and 4) 10% MVC, 90° shoulder flexion. Transcranial magnetic, transmastoid electrical, and Erb’s point stimulation were used to induce motor-evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), and maximal muscle compound potentials (Mmax), respectively, in the biceps brachii in each condition. At rest, MEP, CMEP, and Mmax amplitudes increased ( P < 0.01) by 509.7 ± 118.3%, 113.3 ± 28.3%, and 155.1 ± 47.9%, respectively, at 90° compared with 0°. At 10% MVC, MEP amplitudes did not differ ( P = 0.08), but CMEP and Mmax amplitudes increased ( P < 0.05) by 32.3 ± 10.5% and 127.9 ± 26.1%, respectively, at 90° compared with 0°. MEP/Mmax increased ( P < 0.01) by 224.0 ± 99.1% at rest and decreased ( P < 0.05) by 51.3 ± 6.7% at 10% MVC at 90° compared with 0°. CMEP/Mmax was not different ( P = 0.22) at rest but decreased ( P < 0.01) at 10% MVC by 33.6 ± 6.1% at 90° compared with 0°. EMG increased ( P < 0.001) by 8.3 ± 2.0% at rest and decreased ( P < 0.001) by 21.4 ± 4.4% at 10% MVC at 90° compared with 0°. In conclusion, CSE of the biceps brachii was dependent on shoulder position, and the pattern of change was altered within the state in which it was measured. The position-dependent changes in Mmax amplitude, EMG, and CSE itself all contribute to the overall change in CSE of the biceps brachii. NEW & NOTEWORTHY We demonstrate that when the shoulder is placed into two common positions for determining elbow flexor force and activation, corticospinal excitability (CSE) of the biceps brachii is both shoulder position and state dependent. At rest, when the shoulder is flexed from 0° to 90°, supraspinal factors predominantly alter CSE, whereas during a slight contraction, spinal factors predominantly alter CSE. Finally, the normalization techniques frequently used by researchers to investigate CSE may under- and overestimate CSE when shoulder position is changed.

scholarly journals Effect of graded hypoxia on supraspinal contributions to fatigue with unilateral knee-extensor contractions

2010 ◽  
Vol 109 (6) ◽  
pp. 1842-1851 ◽  
Author(s):  
Stuart Goodall ◽  
Emma Z. Ross ◽  
Lee M. Romer
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Maximal Voluntary Contraction ◽  
Magnetic Stimulation ◽  
Voluntary Contraction ◽  
Corticospinal Excitability ◽  
Voluntary Activation ◽  
Severe Hypoxia ◽  
Knee Extensors ◽  
Moderate Hypoxia

Supraspinal fatigue, defined as an exercise-induced decline in force caused by suboptimal output from the motor cortex, accounts for over one-quarter of the force loss after fatiguing contractions of the knee extensors in normoxia. We tested the hypothesis that the relative contribution of supraspinal fatigue would be elevated with increasing severities of acute hypoxia. On separate days, 11 healthy men performed sets of intermittent, isometric, quadriceps contractions at 60% maximal voluntary contraction to task failure in normoxia (inspired O2 fraction/arterial O2 saturation = 0.21/98%), mild hypoxia (0.16/93%), moderate hypoxia (0.13/85%), and severe hypoxia (0.10/74%). Electrical stimulation of the femoral nerve was performed to assess neuromuscular transmission and contractile properties of muscle fibers. Transcranial magnetic stimulation was delivered to the motor cortex to quantify corticospinal excitability and voluntary activation. After 10 min of breathing the test gas, neuromuscular function and cortical voluntary activation prefatigue were unaffected in any condition. The fatigue protocol resulted in ∼30% declines in maximal voluntary contraction force in all conditions, despite differences in time-to-task failure (24.7 min in normoxia vs. 15.9 min in severe hypoxia, P < 0.05). Potentiated quadriceps twitch force declined in all conditions, but the decline in severe hypoxia was less than that in normoxia ( P < 0.05). Cortical voluntary activation also declined in all conditions, but the deficit in severe hypoxia exceeded that in normoxia ( P < 0.05). The additional central fatigue in severe hypoxia was not due to altered corticospinal excitability, as electromyographic responses to transcranial magnetic stimulation were unchanged. Results indicate that peripheral mechanisms of fatigue contribute relatively more to the reduction in force-generating capacity of the knee extensors following submaximal intermittent isometric contractions in normoxia and mild to moderate hypoxia, whereas supraspinal fatigue plays a greater role in severe hypoxia.

scholarly journals A common neural element receiving rhythmic arm and leg activity as assessed by reflex modulation in arm muscles

2016 ◽  
Vol 115 (4) ◽  
pp. 2065-2075 ◽  
Author(s):  
Syusaku Sasada ◽  
Toshiki Tazoe ◽  
Tsuyoshi Nakajima ◽  
Genki Futatsubashi ◽  
Hiroyuki Ohtsuka ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Motor Evoked Potentials ◽  
Cervical Spinal Cord ◽  
Voluntary Contraction ◽  
Reflex Modulation ◽  
Neural Element ◽  
Single Motor Unit ◽  
Arm Cycling ◽  
Leg Cycling ◽  
Arm Muscles

Neural interactions between regulatory systems for rhythmic arm and leg movements are an intriguing issue in locomotor neuroscience. Amplitudes of early latency cutaneous reflexes (ELCRs) in stationary arm muscles are modulated during rhythmic leg or arm cycling but not during limb positioning or voluntary contraction. This suggests that interneurons mediating ELCRs to arm muscles integrate outputs from neural systems controlling rhythmic limb movements. Alternatively, outputs could be integrated at the motoneuron and/or supraspinal levels. We examined whether a separate effect on the ELCR pathways and cortico-motoneuronal excitability during arm and leg cycling is integrated by neural elements common to the lumbo-sacral and cervical spinal cord. The subjects performed bilateral leg cycling (LEG), contralateral arm cycling (ARM), and simultaneous contralateral arm and bilateral leg cycling (A&L), while ELCRs in the wrist flexor and shoulder flexor muscles were evoked by superficial radial (SR) nerve stimulation. ELCR amplitudes were facilitated by cycling tasks and were larger during A&L than during ARM and LEG. A low stimulus intensity during ARM or LEG generated a larger ELCR during A&L than the sum of ELCRs during ARM and LEG. We confirmed this nonlinear increase in single motor unit firing probability following SR nerve stimulation during A&L. Furthermore, motor-evoked potentials following transcranial magnetic and electrical stimulation did not show nonlinear potentiation during A&L. These findings suggest the existence of a common neural element of the ELCR reflex pathway that is active only during rhythmic arm and leg movement and receives convergent input from contralateral arms and legs.

scholarly journals Corticospinal Excitability to the Biceps Brachii is Not Different When Arm Cycling at a Self-Selected or Fixed Cadence

2019 ◽  
Vol 9 (2) ◽  
pp. 41 ◽  
Author(s):  
Evan Lockyer ◽  
Anna Nippard ◽  
Kaitlyn Kean ◽  
Nicole Hollohan ◽  
Duane Button ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Compound Muscle Action Potential ◽  
Corticospinal Excitability ◽  
Biceps Brachii Muscle ◽  
Muscle Action ◽  
Arm Cycling ◽  
Muscle Action Potential

Background: The present study compared corticospinal excitability to the biceps brachii muscle during arm cycling at a self-selected and a fixed cadence (SSC and FC, respectively). We hypothesized that corticospinal excitability would not be different between the two conditions. Methods: The SSC was initially performed and the cycling cadence was recorded every 5 s for one minute. The average cadence of the SSC cycling trial was then used as a target for the FC of cycling that the participants were instructed to maintain. The motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation (TMS) of the motor cortex were recorded from the biceps brachii during each trial of SSC and FC arm cycling. Results: Corticospinal excitability, as assessed via normalized MEP amplitudes (MEPs were made relative to a maximal compound muscle action potential), was not different between groups. Conclusions: Focusing on maintaining a fixed cadence during arm cycling does not influence corticospinal excitability, as assessed via TMS-evoked MEPs.

Moving forward: methodological considerations when assessing corticospinal excitability during rhythmic motor output in humans

2021 ◽  
Author(s):  
Evan J Lockyer ◽  
Christopher T Compton ◽  
Davis A. Forman ◽  
Gregory E. Pearcey ◽  
Duane C Button ◽  
...  
Keyword(s):  
Neural Control ◽  
Human Movement ◽  
Human Locomotion ◽  
Corticospinal Excitability ◽  
Motor Output ◽  
Rhythmic Motor ◽  
Arm Cycling ◽  
Physiological Relevance ◽  
The Many ◽  
Methodological Considerations

The use of transcranial magnetic stimulation to assess the excitability of the central nervous system to further understand the neural control of human movement is expansive. The majority of the work performed to-date has assessed corticospinal excitability either at rest or during relatively simple isometric contractions. The results from this work are not easily extrapolated to rhythmic, dynamic motor outputs given that corticospinal excitability is task-, phase-, intensity-, direction- and muscle-dependent (Power et al. 2018). Assessing corticospinal excitability during rhythmic motor output, however, involves technical challenges that are to be overcome, or at the minimum considered, when attempting to design experiments and interpret the physiological relevance of the results. The purpose of this narrative review is to highlight research examining corticospinal excitability during a rhythmic motor output and importantly, to provide recommendations regarding the many factors that must be considered when designing and interpreting findings from studies that involve limb movement. To do so, the majority of work described herein refers to work performed using arm cycling (arm pedaling or arm cranking) as a model of a rhythmic motor output used to examine the neural control of human locomotion.

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