scholarly journals Modulation of intracortical inhibition during physically performed and mentally simulated balance tasks

2021 ◽  
Vol 121 (5) ◽  
pp. 1379-1388
Author(s):  
A. Mouthon ◽  
J. Ruffieux ◽  
W. Taube
Keyword(s):  
Motor Evoked Potentials ◽  
Action Observation ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Mental Simulation ◽  
Task Execution ◽  
Postural Tasks ◽  
Execution Condition ◽  
The One ◽  
Postural Task

Abstract Purpose Action observation (AO) during motor imagery (MI), so-called AO + MI, has been proposed as a new form of non-physical training, but the neural mechanisms involved remains largely unknown. Therefore, this study aimed to explore whether there were similarities in the modulation of short-interval intracortical inhibition (SICI) during execution and mental simulation of postural tasks, and if there was a difference in modulation of SICI between AO + MI and AO alone. Method 21 young adults (mean ± SD = 24 ± 6.3 years) were asked to either passively observe (AO) or imagine while observing (AO + MI) or physically perform a stable and an unstable standing task, while motor evoked potentials and SICI were assessed in the soleus muscle. Result SICI results showed a modulation by condition (F2,40 = 6.42, p = 0.009) with less SICI in the execution condition compared to the AO + MI (p = 0.009) and AO (p = 0.002) condition. Moreover, switching from the stable to the unstable stance condition reduced significantly SICI (F1,20 = 8.34, p = 0.009) during both, physically performed (− 38.5%; p = 0.03) and mentally simulated balance (− 10%, p < 0.001, AO + MI and AO taken together). Conclusion The data demonstrate that SICI is reduced when switching from a stable to a more unstable standing task during both real task execution and mental simulation. Therefore, our results strengthen and further support the existence of similarities between executed and mentally simulated actions by showing that not only corticospinal excitability is similarly modulated but also SICI. This proposes that the activity of the inhibitory cortical network during mental simulation of balance tasks resembles the one during physical postural task execution.

scholarly journals Alterations in the cortical control of standing posture during varying levels of postural threat and task difficulty

2018 ◽  
Vol 120 (3) ◽  
pp. 1010-1016 ◽  
Author(s):  
Craig D. Tokuno ◽  
Martin Keller ◽  
Mark G. Carpenter ◽  
Gonzalo Márquez ◽  
Wolfgang Taube
Keyword(s):  
Evoked Potentials ◽  
Task Difficulty ◽  
Motor Evoked Potentials ◽  
Intracortical Inhibition ◽  
Perceived Threat ◽  
Cortical Control ◽  
Corticospinal Pathway ◽  
Postural Threat ◽  
Postural Tasks ◽  
Postural Task

Cortical excitability increases during the performance of more difficult postural tasks. However, it is possible that changes in postural threat associated with more difficult tasks may in themselves lead to alterations in the neural strategies underlying postural control. Therefore, the purpose of this study was to examine whether changes in postural threat are responsible for the alterations in corticospinal excitability and short-interval intracortical inhibition (SICI) that occur with increasing postural task difficulty. Fourteen adults completed three postural tasks (supported standing, free standing, or standing on an unstable board) at two surface heights (ground level or 3 m above ground). Single- and paired-pulse magnetic stimuli were applied to the motor cortex to compare soleus (SOL) and tibialis anterior (TA) test motor-evoked potentials (MEPs) and SICI between conditions. SOL and TA test MEPs increased from 0.35 ± 0.29 to 0.82 ± 0.41 mV (SOL) and from 0.64 ± 0.51 to 1.96 ± 1.45 mV (TA), respectively, whereas SICI decreased from 52.4 ± 17.2% to 39.6 ± 15.4% (SOL) and from 71.3 ± 17.7% to 50.3 ± 19.9% (TA) with increasing task difficulty. In contrast to the effects of task difficulty, only SOL test MEPs were smaller when participants stood at high (0.49 ± 0.29 mV) compared with low height (0.61 ± 0.40 mV). Because the presence of postural threat did not lead to any additional changes in the excitability of the motor corticospinal pathway and intracortical inhibition with increasing task difficulty, it seems unlikely that alterations in perceived threat are primarily responsible for the neurophysiological changes that are observed with increasing postural task difficulty. NEW & NOTEWORTHY We examined how task difficulty and postural threat influence the cortical control of posture. Results indicated that the motor corticospinal pathway and intracortical inhibition were modulated more by task difficulty than postural threat. Furthermore, because the presence of postural threat during the performance of various postural tasks did not lead to summative changes in motor-evoked potentials, alterations in perceived threat are not responsible for the neurophysiological changes that occur with increasing postural task difficulty.

Reduction of Intracortical Inhibition in Soleus Muscle During Postural Activity

2006 ◽  
Vol 96 (4) ◽  
pp. 1711-1717 ◽  
Author(s):  
Oscar Soto ◽  
Josep Valls-Solé ◽  
Paul Shanahan ◽  
John Rothwell
Keyword(s):  
Muscle Contraction ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Voluntary Contraction ◽  
Similar Type ◽  
Similar Extent ◽  
Intracortical Facilitation ◽  
Postural Tasks ◽  
Cortical Involvement

Short-interval intracortical inhibition (SICI) decreases during voluntary contraction of the target muscle. It is unknown whether this effect also occurs with postural contractions. We have compared the effects of voluntary and postural contractions on SICI in the soleus (SOL) muscle. We applied transcranial magnetic stimuli (TMS) in subjects under three tasks: sitting at rest (Rest), sitting while activating the SOL muscle (Voluntary), or standing quietly (Postural). In control trials, we applied suprathreshold TMS to obtain unconditioned motor-evoked potentials (MEPs). In test trials, the same TMS was preceded by a subthreshold TMS at different interstimulus intervals (ISIs), to obtain a conditioned MEP. SICI and intracortical facilitation (ICF) were expressed as the decrease or increase in MEP size relative to unconditioned MEPs. There was significant effect of task in mean SICI or mean ICF in SOL. Mean SICI in SOL was 52% in Rest and decreased to 21% in Voluntary and 15% in Postural. Mean ICF in SOL was 132% and decreased to 113% in Voluntary and to 108% in Postural. Mean SICI in SOL was not different in Voluntary and Postural tasks. There was no effect of task in mean SICI or mean ICF in TA. Our results indicate that decrease of SICI with muscle contraction occurs to a similar extent with tonic voluntary and postural activation, suggesting that those contractions require a similar type of cortical involvement. However, it cannot be excluded that some part of the SICI reduction with muscle contraction depends on changes in segmental excitability.

scholarly journals The value of corticospinal excitability and intracortical inhibition in predicting motor skill improvement driven by action observation

2021 ◽  
Author(s):  
Arturo Nuara ◽  
Maria Chiara Bazzini ◽  
Pasquale Cardellicchio ◽  
Emilia Scalona ◽  
Doriana De Marco ◽  
...  
Keyword(s):  
Motor Skill ◽  
Motor Evoked Potentials ◽  
Action Observation ◽  
Short Interval ◽  
Silent Period ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Two Phase ◽  
Rehabilitative Treatment ◽  
Skill Improvement

BACKGROUND AND OBJECTIVE: Action observation can sustain motor skill improvement. At the neurophysiological level, action observation affects the excitability of the motor cortices, as measured by transcranial magnetic stimulation. However, whether the cortical modulations induced by action observation may explain the amount of motor improvement driven by action observation training (AOT) remains to be addressed. METHODS: We conducted a two-phase study involving 40 volunteers. First, we assessed the effect of action observation on corticospinal excitability (amplitude of motor evoked potentials), short-interval intracortical inhibition, and transcallosal inhibition (ipsilateral silent period). Subsequently, a randomized-controlled design was applied, with AOT participants asked to observe and then execute, as quickly as possible, a right-hand dexterity task six consecutive times, whereas controls had to observe a no-action video before performing the same task. RESULTS: AOT participants showed greater performance improvement relative to controls. The amount of improvement in the AOT group was predicted by the amplitude of corticospinal modulation during action observation and even more by the amount of intracortical inhibition induced by action observation. Importantly, these relations were found specifically for the AOT group and not for the controls. CONCLUSIONS: In this study, we identified the neurophysiological signatures associated with, and potentially sustaining, the outcome of AOT. Intracortical inhibition driven by action observation plays a major role. These findings elucidate the cortical mechanisms underlying AOT efficacy and open to predictive assessments for the identification of potential responders to AOT, informing the rehabilitative treatment individualization.

Intracortical Inhibition During Volitional Inhibition of Prepared Action

2006 ◽  
Vol 95 (6) ◽  
pp. 3371-3383 ◽  
Author(s):  
James P. Coxon ◽  
Cathy M. Stinear ◽  
Winston D. Byblow
Keyword(s):  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Corticomotor Excitability ◽  
Hand Muscles ◽  
Cortical Level ◽  
A Site ◽  
Intrinsic Hand Muscles ◽  
Inhibitory Networks

Volitional inhibition is the voluntary prevention of a prepared movement. Here we ask whether primary motor cortex (M1) is a site of convergence of cortical activity associated with movement preparation and volitional inhibition. Volitional inhibition was studied by presenting a stop signal before execution of an anticipated response that requires a key lift to intercept a revolving dial. Motor evoked potentials (MEPs) were elicited in intrinsic hand muscles by transcranial magnetic stimulation (TMS) to assess corticomotor excitability and short interval intracortical inhibition (sICI) during task performance. The closer the stop cue was presented to the anticipated response, the harder it was for subjects to inhibit their response. Corticomotor pathway excitability was temporally modulated during volitional inhibition. Using subthreshold TMS, corticomotor excitability was reduced for Stop trials relative to Go trials from 140 ms after the cue. sICI was significantly greater for Stop trials compared with Go trials at a time that preceded the onset of muscle activity associated with the anticipated response. These results provide evidence that volitional inhibition is exerted at a cortical level and that inhibitory networks within M1 contribute to volitional inhibition of prepared action.

scholarly journals Physiological changes underlying bilateral isometric arm voluntary contractions in healthy humans

2011 ◽  
Vol 105 (4) ◽  
pp. 1594-1602 ◽  
Author(s):  
Demetris S. Soteropoulos ◽  
Monica A. Perez
Keyword(s):  
Tibialis Anterior ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Voluntary Contraction ◽  
Triceps Brachii ◽  
Hand Muscles ◽  
Healthy Humans ◽  
Simultaneous Activation ◽  
The Right

Many bilateral motor tasks engage simultaneous activation of distal and proximal arm muscles, but little is known about their physiological interactions. Here, we used transcranial magnetic stimulation to examine motor-evoked potentials (MEPs), interhemispheric inhibition at a conditioning-test interval of 10 (IHI10) and 40 ms (IHI40), and short-interval intracortical inhibition (SICI) in the left first dorsal interosseous (FDI) muscle during isometric index finger abduction. The right side remained at rest or performed isometric voluntary contraction with the FDI, biceps or triceps brachii, or the tibialis anterior. Left FDI MEPs were suppressed to a similar extent during contraction of the right FDI and biceps and triceps brachii but remained unchanged during contraction of the right tibialis anterior. IHI10 and IHI40 were decreased during contraction of the right biceps and triceps brachii compared with contraction of the right FDI. SICI was increased during activation of the right biceps and triceps brachii and decreased during activation of the right FDI. The present results indicate that an isometric voluntary contraction with either a distal or a proximal arm muscle, but not a foot dorsiflexor, decreases corticospinal output in a contralateral active finger muscle. Transcallosal inhibitory effects were strong during bilateral activation of distal hand muscles and weak during simultaneous activation of a distal and a proximal arm muscle, whereas GABAergic intracortical activity was modulated in the opposite manner. These findings suggest that in intact humans crossed interactions at the level of the motor cortex involved different physiological mechanisms when bilateral distal hand muscles are active and when a distal and a proximal arm muscle are simultaneously active.

scholarly journals Motor facilitation during action observation: a magnetic stimulation study

1995 ◽  
Vol 73 (6) ◽  
pp. 2608-2611 ◽  
Author(s):  
L. Fadiga ◽  
L. Fogassi ◽  
G. Pavesi ◽  
G. Rizzolatti
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Muscle Activity ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Action Observation ◽  
Normal Subjects ◽  
Hand Muscles ◽  
3D Objects ◽  
The One

1. We stimulated the motor cortex of normal subjects (transcranial magnetic stimulation) while they 1) observed an experimenter grasping 3D-objects, 2) looked at the same 3D-objects, 3) observed an experimenter tracing geometrical figures in the air with his arm, and 4) detected the dimming of a light. Motor evoked potentials (MEPs) were recorded from hand muscles. 2. We found that MEPs significantly increased during the conditions in which subjects observed movements. The MEP pattern reflected the pattern of muscle activity recorded when the subjects executed the observed actions. 3. We conclude that in humans there is a system matching action observation and execution. This system resembles the one recently described in the monkey.

Event-related desynchronization reflects downregulation of intracortical inhibition in human primary motor cortex

2013 ◽  
Vol 110 (5) ◽  
pp. 1158-1166 ◽  
Author(s):  
Mitsuaki Takemi ◽  
Yoshihisa Masakado ◽  
Meigen Liu ◽  
Junichi Ushiba
Keyword(s):  
Motor Cortex ◽  
Motor Imagery ◽  
Sensorimotor Cortex ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Hand Movement ◽  
Intracortical Inhibition ◽  
Imagery Task ◽  
Event Related Desynchronization

There is increasing interest in electroencephalogram (EEG)-based brain-computer interface (BCI) as a tool for rehabilitation of upper limb motor functions in hemiplegic stroke patients. This type of BCI often exploits mu and beta oscillations in EEG recorded over the sensorimotor areas, and their event-related desynchronization (ERD) following motor imagery is believed to represent increased sensorimotor cortex excitability. However, it remains unclear whether the sensorimotor cortex excitability is actually correlated with ERD. Thus we assessed the association of ERD with primary motor cortex (M1) excitability during motor imagery of right wrist movement. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) with transcranial magnetic stimulation (TMS). Twenty healthy participants were recruited. The participants performed 7 s of rest followed by 5 s of motor imagery and received online visual feedback of the ERD magnitude of the contralateral hand M1 while performing the motor imagery task. TMS was applied to the right hand M1 when ERD exceeded predetermined thresholds during motor imagery. MEP amplitudes, SICI, and ICF were recorded from the agonist muscle of the imagined hand movement. Results showed that the large ERD during wrist motor imagery was associated with significantly increased MEP amplitudes and reduced SICI but no significant changes in ICF. Thus ERD magnitude during wrist motor imagery represents M1 excitability. This study provides electrophysiological evidence that a motor imagery task involving ERD may induce changes in corticospinal excitability similar to changes accompanying actual movements.

scholarly journals Writing's Shadow: Corticospinal Activation during Letter Observation

2012 ◽  
Vol 24 (5) ◽  
pp. 1138-1148 ◽  
Author(s):  
Masahiro Nakatsuka ◽  
Mohamed Nasreldin Thabit ◽  
Satoko Koganemaru ◽  
Ippei Nojima ◽  
Hidenao Fukuyama ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Single Pulse ◽  
Random Order ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Motor Memory ◽  
F Wave ◽  
The Right

We can recognize handwritten letters despite the variability among writers. One possible strategy is exploiting the motor memory of orthography. By using TMS, we clarified the excitatory and inhibitory neural circuits of the motor corticospinal pathway that might be activated during the observation of handwritten letters. During experiments, participants looked at the handwritten or printed single letter that appeared in a random order. The excitability of the left and right primary motor cortex (M1) was evaluated by motor-evoked potentials elicited by single-pulse TMS. Short interval intracortical inhibition (SICI) of the left M1 was evaluated using paired-pulse TMS. F waves were measured for the right ulnar nerve. We found significant reduction of corticospinal excitability only for the right hand at 300–400 msec after each letter presentation without significant changes in SICI. This suppression is likely to be of supraspinal origin, because of no significant alteration in F-wave amplitudes. These findings suggest that the recognition of handwritten letters may include the implicit knowledge of “writing” in M1. The M1 activation associated with that process, which has been shown in previous neuroimaging studies, is likely to reflect the active suppression of the corticospinal excitability.

Corticomotor plasticity and learning of a ballistic thumb training task are diminished in older adults

2009 ◽  
Vol 107 (6) ◽  
pp. 1874-1883 ◽  
Author(s):  
Nigel C. Rogasch ◽  
Tamara J. Dartnall ◽  
John Cirillo ◽  
Michael A. Nordstrom ◽  
John G. Semmler
Keyword(s):  
Older Adults ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Training Task ◽  
Abductor Pollicis Brevis ◽  
Corticomotor Excitability ◽  
Old Adults ◽  
Young Subjects

This study examined changes in corticomotor excitability and plasticity after a thumb abduction training task in young and old adults. Electromyographic (EMG) recordings were obtained from right abductor pollicis brevis (APB, target muscle) and abductor digiti minimi (ADM, control muscle) in 14 young (18–24 yr) and 14 old (61–82 yr) adults. The training task consisted of 300 ballistic abductions of the right thumb to maximize peak thumb abduction acceleration (TAAcc). Transcranial magnetic stimulation (TMS) of the left primary motor cortex was used to assess changes in APB and ADM motor evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) before, immediately after, and 30 min after training. No differences in corticomotor excitability (resting and active TMS thresholds, MEP input-output curves) or SICI were observed in young and old adults before training. Motor training resulted in improvements in peak TAAcc in young (177% improvement, P < 0.001) and old (124%, P = 0.005) subjects, with greater improvements in young subjects ( P = 0.002). Different thumb kinematics were observed during task performance, with increases in APB EMG related to improvements in peak TAAcc in young ( r2 = 0.46, P = 0.008) but not old ( r2 = 0.09, P = 0.3) adults. After training, APB MEPs were 50% larger ( P < 0.001 compared with before) in young subjects, with no change after training in old subjects ( P = 0.49), suggesting reduced use-dependent corticomotor plasticity with advancing age. These changes were specific to APB, because no training-related change in MEP amplitude was observed in ADM. No significant association was observed between change in APB MEP and improvement in TAAcc with training in individual young and old subjects. SICI remained unchanged after training in both groups, suggesting that it was not responsible for the diminished use-dependent corticomotor plasticity for this task in older adults.

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