Shouting strengthens maximal voluntary force and is associated with augmented pupillary dilation

AbstractPrevious research has demonstrated that human maximal voluntary force is generally limited by neural inhibition. Producing a shout during maximal exertion effort enhances the force levels of maximal voluntary contraction. However, the mechanisms underlying this enhancement effect on force production remain unclear. We investigated the influence of producing a shout on the pupil-linked neuromodulatory system state by examining pupil size. We also examined its effects on the motor system state by examining motor evoked potentials in response to transcranial magnetic stimulation applied over the contralateral primary motor cortex, and by evaluating handgrip maximal voluntary force. Analysis revealed that producing a shout significantly increased handgrip maximal voluntary force, followed by an increase in pupil size and a reduction of the cortical silent period. Our results indicate that producing a shout increased handgrip maximal voluntary force through the enhancement of motor cortical excitability, possibly via the enhancement of noradrenergic system activity. This study provides evidence that the muscular force-enhancing effect of shouting during maximal force exertion is related to both the motor system state and the pupil-linked neuromodulatory system state.

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Shouting Strengthens Maximal Voluntary Force with Pupillary Dilation

10.21203/rs.3.rs-549858/v1 ◽

2021 ◽

Author(s):

Yudai Takarada ◽

Daichi Nozaki

Keyword(s):

Pupil Size ◽

Motor System ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Force Production ◽

Silent Period ◽

System State ◽

Enhancing Effect ◽

Maximal Voluntary Force

Abstract Previous research has demonstrated that human maximal voluntary force is generally limited by neural inhibition. Indeed, producing a shout during maximal exertion efforts enhances the force levels of maximum voluntary contractions. However, the mechanisms underlying this enhancing effect of force production remain unknown. We investigated the influence of a shout on the pupil-linked neuromodulatory system state by examining pupil size. We also examined its effect on the motor system state by examining motor evoked potentials in response to transcranial magnetic stimulation applied over the contralateral primary motor cortex, and by evaluating the handgrip maximal voluntary force. Analysis showed that a shout significantly increased the handgrip maximal voluntary force, followed by an increase in pupil size and a reduction of the cortical silent period. Our results indicate that a shout can increase handgrip maximal voluntary force through the enhancement of motor cortical excitability, possibly via the enhancement of noradrenergic system activity. This study provides evidence that the muscular force-enhancing effect of a shout during maximal force exertion is related to both the motor system state and the pupil-linked neuromodulatory system state.

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Cerebellar rTMS and PAS effectively induce cerebellar plasticity

Scientific Reports ◽

10.1038/s41598-021-82496-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Martje G. Pauly ◽

Annika Steinmeier ◽

Christina Bolte ◽

Feline Hamami ◽

Elinor Tzvi ◽

...

Keyword(s):

Motor Cortex ◽

Healthy Subjects ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Repetitive Transcranial Magnetic Stimulation ◽

Premotor Cortex ◽

Motor Pathways ◽

Non Invasive ◽

Cerebellar Plasticity

AbstractNon-invasive brain stimulation techniques including repetitive transcranial magnetic stimulation (rTMS), continuous theta-burst stimulation (cTBS), paired associative stimulation (PAS), and transcranial direct current stimulation (tDCS) have been applied over the cerebellum to induce plasticity and gain insights into the interaction of the cerebellum with neo-cortical structures including the motor cortex. We compared the effects of 1 Hz rTMS, cTBS, PAS and tDCS given over the cerebellum on motor cortical excitability and interactions between the cerebellum and dorsal premotor cortex / primary motor cortex in two within subject designs in healthy controls. In experiment 1, rTMS, cTBS, PAS, and tDCS were applied over the cerebellum in 20 healthy subjects. In experiment 2, rTMS and PAS were compared to sham conditions in another group of 20 healthy subjects. In experiment 1, PAS reduced cortical excitability determined by motor evoked potentials (MEP) amplitudes, whereas rTMS increased motor thresholds and facilitated dorsal premotor-motor and cerebellum-motor cortex interactions. TDCS and cTBS had no significant effects. In experiment 2, MEP amplitudes increased after rTMS and motor thresholds following PAS. Analysis of all participants who received rTMS and PAS showed that MEP amplitudes were reduced after PAS and increased following rTMS. rTMS also caused facilitation of dorsal premotor-motor cortex and cerebellum-motor cortex interactions. In summary, cerebellar 1 Hz rTMS and PAS can effectively induce plasticity in cerebello-(premotor)-motor pathways provided larger samples are studied.

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Online and offline effects of transcranial alternating current stimulation of the primary motor cortex

Scientific Reports ◽

10.1038/s41598-021-83449-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ivan Pozdniakov ◽

Alicia Nunez Vorobiova ◽

Giulia Galli ◽

Simone Rossi ◽

Matteo Feurra

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Random Noise ◽

Single Pulse ◽

Alternating Current ◽

Online Application ◽

Transcranial Random Noise Stimulation ◽

Transcranial Alternating Current Stimulation

AbstractTranscranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that allows interaction with endogenous cortical oscillatory rhythms by means of external sinusoidal potentials. The physiological mechanisms underlying tACS effects are still under debate. Whereas online (e.g., ongoing) tACS over the motor cortex induces robust state-, phase- and frequency-dependent effects on cortical excitability, the offline effects (i.e. after-effects) of tACS are less clear. Here, we explored online and offline effects of tACS in two single-blind, sham-controlled experiments. In both experiments we used neuronavigated transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) as a probe to index changes of cortical excitability and delivered M1 tACS at 10 Hz (alpha), 20 Hz (beta) and sham (30 s of low-frequency transcranial random noise stimulation; tRNS). Corticospinal excitability was measured by single pulse TMS-induced motor evoked potentials (MEPs). tACS was delivered online in Experiment 1 and offline in Experiment 2. In Experiment 1, the increase of MEPs size was maximal with the 20 Hz stimulation, however in Experiment 2 neither the 10 Hz nor the 20 Hz stimulation induced tACS offline effects. These findings support the idea that tACS affects cortical excitability only during online application, at least when delivered on the scalp overlying M1, thereby contributing to the development of effective protocols that can be applied to clinical populations.

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The Influence of Cortico-Cerebellar Structural Connectivity on Cortical Excitability in Chronic Stroke

Cerebral Cortex ◽

10.1093/cercor/bhz169 ◽

2019 ◽

Vol 30 (3) ◽

pp. 1330-1344

Author(s):

Stephanie Guder ◽

Benedikt M Frey ◽

Winifried Backhaus ◽

Hanna Braass ◽

Jan E Timmermann ◽

...

Keyword(s):

Primary Motor Cortex ◽

Structural Integrity ◽

Cortical Excitability ◽

Structural Information ◽

Motor Evoked Potentials ◽

Structural Connectivity ◽

Chronic Stroke ◽

Motor Output ◽

Healthy Controls ◽

Stroke Patients

Abstract Brain imaging has recently evidenced that the structural state of distinct reciprocal cortico-cerebellar fiber tracts, the dentato-thalamo-cortical tract (DTCT), and the cortico-ponto-cerebellar tract (CPCeT), significantly influences residual motor output in chronic stroke patients, independent from the level of damage to the corticospinal tract (CST). Whether such structural information might also directly relate to measures of cortical excitability is an open question. Eighteen chronic stroke patients with supratentorial ischemic lesions and 17 healthy controls underwent transcranial magnetic stimulation to assess recruitment curves of motor evoked potentials of both hemispheres. Diffusion-weighted imaging and probabilistic tractography were applied to reconstruct reciprocal cortico-cerebellar motor tracts between the primary motor cortex and the cerebellum. Tract-related microstructure was estimated by means of fractional anisotropy, and linear regression modeling was used to relate it to cortical excitability. The main finding was a significant association between cortical excitability and the structural integrity of the DTCT, the main cerebellar outflow tract, independent from the level of damage to the CST. A comparable relationship was neither detectable for the CPCeT nor for the healthy controls. This finding contributes to a mechanistic understanding of the putative supportive role of the cerebellum for residual motor output by facilitating cortical excitability after stroke.

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Chronic low-frequency rTMS of primary motor cortex diminishes exercise training-induced gains in maximal voluntary force in humans

Journal of Applied Physiology ◽

10.1152/japplphysiol.90701.2008 ◽

2009 ◽

Vol 106 (2) ◽

pp. 403-411 ◽

Cited By ~ 20

Author(s):

Tibor Hortobágyi ◽

Sarah Pirio Richardson ◽

Mikhael Lomarev ◽

Ejaz Shamim ◽

Sabine Meunier ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Repetitive Transcranial Magnetic Stimulation ◽

Low Frequency ◽

Motor Evoked Potential ◽

Single Pulse ◽

Compound Action Potential ◽

Voluntary Contraction ◽

Maximal Voluntary Force ◽

Resting Motor Threshold

Although there is consensus that the central nervous system mediates the increases in maximal voluntary force (maximal voluntary contraction, MVC) produced by resistance exercise, the involvement of the primary motor cortex (M1) in these processes remains controversial. We hypothesized that 1-Hz repetitive transcranial magnetic stimulation (rTMS) of M1 during resistance training would diminish strength gains. Forty subjects were divided equally into five groups. Subjects voluntarily (Vol) abducted the first dorsal interosseus (FDI) (5 bouts × 10 repetitions, 10 sessions, 4 wk) at 70–80% MVC. Another group also exercised but in the 1-min-long interbout rest intervals they received rTMS [Vol+rTMS, 1 Hz, FDI motor area, 300 pulses/session, 120% of the resting motor threshold (rMT)]. The third group also exercised and received sham rTMS (Vol+Sham). The fourth group received only rTMS (rTMS_only). The 37.5% and 33.3% gains in MVC in Vol and Vol+Sham groups, respectively, were greater ( P = 0.001) than the 18.9% gain in Vol+rTMS, 1.9% in rTMS_only, and 2.6% in unexercised control subjects who received no stimulation. Acutely, within sessions 5 and 10, single-pulse TMS revealed that motor-evoked potential size and recruitment curve slopes were reduced in Vol+rTMS and rTMS_only groups and accumulated to chronic reductions by session 10. There were no changes in rMT, maximum compound action potential amplitude (Mmax), and peripherally evoked twitch forces in the trained FDI and the untrained abductor digiti minimi. Although contributions from spinal sources cannot be excluded, the data suggest that M1 may play a role in mediating neural adaptations to strength training.

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Expanding the parameter space of anodal transcranial direct current stimulation of the primary motor cortex

Scientific Reports ◽

10.1038/s41598-019-54621-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 10

Author(s):

Desmond Agboada ◽

Mohsen Mosayebi Samani ◽

Asif Jamil ◽

Min-Fang Kuo ◽

Michael A. Nitsche

Keyword(s):

Motor Cortex ◽

Parameter Space ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Anodal Tdcs ◽

Stimulation Parameters ◽

Motor Cortex Excitability ◽

The Impact ◽

Motor Cortex Plasticity

AbstractSize and duration of the neuroplastic effects of tDCS depend on stimulation parameters, including stimulation duration and intensity of current. The impact of stimulation parameters on physiological effects is partially non-linear. To improve the utility of this intervention, it is critical to gather information about the impact of stimulation duration and intensity on neuroplasticity, while expanding the parameter space to improve efficacy. Anodal tDCS of 1–3 mA current intensity was applied for 15–30 minutes to study motor cortex plasticity. Sixteen healthy right-handed non-smoking volunteers participated in 10 sessions (intensity-duration pairs) of stimulation in a randomized cross-over design. Transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEP) were recorded as outcome measures of tDCS effects until next evening after tDCS. All active stimulation conditions enhanced motor cortex excitability within the first 2 hours after stimulation. We observed no significant differences between the three stimulation intensities and durations on cortical excitability. A trend for larger cortical excitability enhancements was however observed for higher current intensities (1 vs 3 mA). These results add information about intensified tDCS protocols and suggest that the impact of anodal tDCS on neuroplasticity is relatively robust with respect to gradual alterations of stimulation intensity, and duration.

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Time Course of Determination of Movement Direction in the Reaction Time Task in Humans

Journal of Neurophysiology ◽

10.1152/jn.2001.86.3.1195 ◽

2001 ◽

Vol 86 (3) ◽

pp. 1195-1201 ◽

Cited By ~ 18

Author(s):

Martin Sommer ◽

Joseph Classen ◽

Leonardo G. Cohen ◽

Mark Hallett

Keyword(s):

Reaction Time ◽

Motor Cortex ◽

Time Course ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Movement Direction ◽

Movement Onset ◽

Thumb Movement

The primary motor cortex produces motor commands that include encoding the direction of movement. Excitability of the motor cortex in the reaction time (RT) task can be assessed using transcranial magnetic stimulation (TMS). To elucidate the timing of the increase in cortical excitability and of the determination of movement direction before movement onset, we asked six right-handed, healthy subjects to either abduct or extend their right thumb after a go-signal indicated the appropriate direction. Between the go-signal and movement onset, single TMS pulses were delivered to the contralateral motor cortex. We recorded the direction of the TMS-induced thumb movement and the amplitude of motor-evoked potentials (MEPs) from the abductor pollicis brevis and extensor pollicis brevis muscles. Facilitation of MEPs from the prime mover, as early as 200 ms before the end of the reaction time, preceded facilitation of MEPs from the nonprime mover, and both preceded measurable directional change. Compared with a control condition in which no voluntary movement was required, the direction of the TMS-induced thumb movement started to change in the direction of the intended movement as early as 90 ms before the end of the RT, and maximum changes were seen shortly before the end of reaction time. Movement acceleration also increased with maxima shortly before the end of the RT. We conclude that in concentric movements a change of the movement direction encoded in the primary motor cortex occurs in the 200 ms prior to movement onset, which is as early as increased excitability itself can be detected.

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Transcranial random noise stimulation (tRNS): a wide range of frequencies is needed for increasing cortical excitability

Scientific Reports ◽

10.1038/s41598-019-51553-7 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 6

Author(s):

Beatrice Moret ◽

Rita Donato ◽

Massimo Nucci ◽

Giorgia Cona ◽

Gianluca Campana

Keyword(s):

Frequency Band ◽

High Frequency ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Random Noise ◽

High Frequency Band ◽

Neural Excitability ◽

Transcranial Random Noise Stimulation ◽

Wide Range

Abstract Transcranial random noise stimulation (tRNS) is a recent neuromodulation protocol. The high-frequency band (hf-tRNS) has shown to be the most effective in enhancing neural excitability. The frequency band of hf-tRNS typically spans from 100 to 640 Hz. Here we asked whether both the lower and the higher half of the high-frequency band are needed for increasing neural excitability. Three frequency ranges (100–400 Hz, 400–700 Hz, 100–700 Hz) and Sham conditions were delivered for 10 minutes at an intensity of 1.5 mA over the primary motor cortex (M1). Single-pulse transcranial magnetic stimulation (TMS) was delivered over the same area at baseline, 0, 10, 20, 30, 45 and 60 minutes after stimulation, while motor evoked potentials (MEPs) were recorded to evaluate changes in cortical excitability. Only the full-band condition (100–700 Hz) was able to modulate excitability by enhancing MEPs at 10 and 20 minutes after stimulation: neither the higher nor the lower sub-range of the high-frequency band significantly modulated cortical excitability. These results show that the efficacy of tRNS is strictly related to the width of the selected frequency range.

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Automatic Recruitment of the Motor System by Undetected Graspable Objects: A Motor-evoked Potential Study

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01165 ◽

2017 ◽

Vol 29 (11) ◽

pp. 1918-1931 ◽

Cited By ~ 5

Author(s):

Nicolas A. McNair ◽

Ashleigh D. Behrens ◽

Irina M. Harris

Keyword(s):

Evoked Potentials ◽

Visual Processing ◽

Motor System ◽

Primary Motor Cortex ◽

Direct Evidence ◽

Motor Evoked Potentials ◽

Motor Evoked Potential ◽

Motor Action ◽

Motor Pathway ◽

The Right

Previous behavioral and neuroimaging studies have suggested that the motor properties associated with graspable objects may be automatically accessed when people passively view these objects. We directly tested this by measuring the excitability of the motor pathway when participants viewed pictures of graspable objects that were presented during the attentional blink (AB), when items frequently go undetected. Participants had to identify two briefly presented objects separated by either a short or long SOA. Motor-evoked potentials were measured from the right hand in response to a single TMS pulse delivered over the left primary motor cortex 250 msec after the onset of the second target. Behavioral results showed poorer identification of objects at short SOA compared with long SOA, consistent with an AB, which did not differ between graspable and nongraspable objects. However, motor-evoked potentials measured during the AB were significantly higher for graspable objects than for nongraspable objects, irrespective of whether the object was successfully identified or undetected. This provides direct evidence that the motor system is automatically activated during visual processing of objects that afford a motor action.

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EEG Coherence Analysis for Suppression of MEP Amplitude Variability in TMS

International Journal of Online and Biomedical Engineering (iJOE) ◽

10.3991/ijoe.v17i06.22553 ◽

2021 ◽

Vol 17 (06) ◽

pp. 87

Author(s):

Keisuke Sasaki ◽

Yuki Fujishige ◽

Masato Odagaki

Keyword(s):

Cortical Neurons ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Motor Evoked Potential ◽

Coherence Analysis ◽

Eeg Coherence ◽

Peripheral Muscle ◽

Online Measurements ◽

Stimulation Method

Transcranial magnetic stimulation (TMS) is a non-invasive stimulation method for cortical neurons. When TMS is delivered to the primary motor cortex (M1), motor evoked potentials can be measured in electromyograms for the peripheral muscle. However, the motor-evoked potential (MEP) amplitudes measured by stimulations for M1 fluctuated from trial to trial. MEP fluctuations are caused by changes in cortical excitability. We hypothesized that MEP variability could be suppressed with application of TMS when cortical excitability was stable. Thus, we developed a TMS system to suppress MEP amplitude variabilities. We used electroencephalographic (EEG) online measurements with coherence analysis to obtain the similarity of cortical excitabilities. The system enables us to trigger TMS if the EEGs measured from the two channels have a high similarity in the frequency domain. In this study, we found that the suppression of MEP fluctuation was dependent on the state of cortical excitability obtained by EEG coherence analysis.

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