scholarly journals EEG-triggered TMS reveals stronger brain state-dependent modulation of motor evoked potentials at weaker stimulation intensities

2018 ◽  
Author(s):  
Natalie Schaworonkow ◽  
Jochen Triesch ◽  
Ulf Ziemann ◽  
Christoph Zrenner
Keyword(s):  
Evoked Potentials ◽  
Real Time ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Brain State ◽  
Stimulation Intensity ◽  
Negative Peak ◽  
State Dependent ◽  
Wide Range ◽  
Brain States

AbstractBackgroundCorticospinal excitability depends on the current brain state. The recent development of real-time EEG-triggered transcranial magnetic stimulation (EEG-TMS) allows studying this relationship in a causal fashion. Specifically, it has been shown that corticospinal excitability is higher during the scalp surface negative EEG peak compared to the positive peak of µ-oscillations in sensorimotor cortex, as indexed by larger motor evoked potentials (MEPs) for fixed stimulation intensity.ObjectiveWe further characterize the effect of µ-rhythm phase on the MEP input-output (IO) curve by measuring the degree of excitability modulation across a range of stimulation intensities. We furthermore seek to optimize stimulation parameters to enable discrimination of functionally relevant EEG-defined brain states.MethodsA real-time EEG-TMS system was used to trigger MEPs during instantaneous brain-states corresponding to µ-rhythm surface positive and negative peaks with five different stimulation intensities covering an individually calibrated MEP IO curve in 15 healthy participants.ResultsMEP amplitude is modulated by µ-phase across a wide range of stimulation intensities, with larger MEPs at the surface negative peak. The largest relative MEP-modulation was observed for weak intensities, the largest absolute MEP-modulation for intermediate intensities. These results indicate a leftward shift of the MEP IO curve during the µ-rhythm negative peak.ConclusionThe choice of stimulation intensity influences the observed degree of corticospinal excitability modulation by µ-phase. Lower stimulation intensities enable more efficient differentiation of EEG µ-phase-defined brain states.

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 EEG-triggered TMS reveals stronger brain state-dependent modulation of motor evoked potentials at weaker stimulation intensities

2019 ◽  
Vol 12 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Natalie Schaworonkow ◽  
Jochen Triesch ◽  
Ulf Ziemann ◽  
Christoph Zrenner
Keyword(s):  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Brain State ◽  
State Dependent

scholarly journals Transspinal stimulation decreases corticospinal excitability and alters the function of spinal locomotor networks

2019 ◽  
Vol 122 (6) ◽  
pp. 2331-2343 ◽  
Author(s):  
Timothy S. Pulverenti ◽  
Md. Anamul Islam ◽  
Ola Alsalman ◽  
Lynda M. Murray ◽  
Noam Y. Harel ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Surface Emg ◽  
Corticospinal Excitability ◽  
Emg Activity ◽  
Step Cycle ◽  
Healthy Humans ◽  
Descending Volleys ◽  
Period Duration

Locomotion requires the continuous integration of descending motor commands and sensory inputs from the legs by spinal central pattern generator circuits. Modulation of spinal neural circuits by transspinal stimulation is well documented, but how transspinal stimulation affects corticospinal excitability during walking in humans remains elusive. We measured the motor evoked potentials (MEPs) at multiple phases of the step cycle conditioned with transspinal stimulation delivered at sub- and suprathreshold intensities of the spinally mediated transspinal evoked potential (TEP). Transspinal stimulation was delivered before or after transcranial magnetic stimulation during which summation between MEP and TEP responses in the surface EMG was absent or present. Relationships between MEP amplitude and background EMG activity, silent period duration, and phase-dependent EMG amplitude modulation during and after stimulation were also determined. Ankle flexor and extensor MEPs were depressed by suprathreshold transspinal stimulation when descending volleys were timed to interact with transspinal stimulation-induced motoneuron depolarization at the spinal cord. MEP depression coincided with decreased MEP gain, unaltered MEP threshold, and unaltered silent period duration. Locomotor EMG activity of bilateral knee and ankle muscles was significantly depressed during the step at which transspinal stimulation was delivered but fully recovered at the subsequent step. The results support a model in which MEP depression by transspinal stimulation occurs via subcortical or spinal mechanisms. Transspinal stimulation disrupts the locomotor output of flexor and extensor motoneurons initially, but the intact nervous system has the ability to rapidly overcome this pronounced locomotor adaptation. In conclusion, transspinal stimulation directly affects spinal locomotor centers in healthy humans. NEW & NOTEWORTHY Lumbar transspinal stimulation decreases ankle flexor and extensor motor evoked potentials (MEPs) during walking. The MEP depression coincides with decreased MEP gain, unaltered MEP threshold changes, and unaltered silent period duration. These findings indicate that MEP depression is subcortical or spinal in origin. Healthy subjects could rapidly overcome the pronounced depression of muscle activity during the step at which transspinal stimulation was delivered. Thus, transspinal stimulation directly affects the function of spinal locomotor networks in healthy humans.

P41 Semi-automatic cleaning of resting state EEG and motor-evoked potentials – Application and importance for brain state estimation

2020 ◽  
Vol 131 (4) ◽  
pp. e35-e36
Author(s):  
J. Metsomaa ◽  
C. Zrenner ◽  
P. Belardinelli ◽  
M. Ermolova ◽  
P. Gordon ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
State Estimation ◽  
Resting State ◽  
Motor Evoked Potentials ◽  
Brain State

scholarly journals Training voluntary motor suppression with real-time feedback of motor evoked potentials

2015 ◽  
Vol 113 (9) ◽  
pp. 3446-3452 ◽  
Author(s):  
D. S. Adnan Majid ◽  
Christina Lewis ◽  
Adam R. Aron
Keyword(s):  
Motor Cortex ◽  
Evoked Potentials ◽  
Real Time ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
High Temporal Resolution ◽  
Double Blind Study ◽  
Training Procedure ◽  
Double Blind ◽  
Control Response

Training people to suppress motor representations voluntarily could improve response control. We evaluated a novel training procedure of real-time feedback of motor evoked potentials (MEPs) generated by transcranial magnetic stimulation (TMS) over motor cortex. On each trial, a cue instructed participants to use a mental strategy to suppress a particular finger representation without overt movement. A single pulse of TMS was delivered over motor cortex, and an MEP-derived measure of hand motor excitability was delivered visually to the participant within 500 ms. In experiment 1, we showed that participants learned to reduce the excitability of a particular finger beneath baseline (selective motor suppression) within 30 min of practice. In experiment 2, we performed a double-blind study with 2 training groups (1 with veridical feedback and 1 with matched sham feedback) to show that selective motor suppression depends on the veridical feedback itself. Experiment 3 further demonstrated the importance of veridical feedback by showing that selective motor suppression did not arise from mere mental imagery, even when incentivized with reward. Thus participants can use real-time feedback of TMS-induced MEPs to discover an effective mental strategy for selective motor suppression. This high-temporal-resolution, trial-by-trial-feedback training method could be used to help people better control response tendencies and may serve as a potential therapy for motor disorders such as Tourette's and dystonia.

Brain State-Dependent Transcranial Magnetic Closed-Loop Stimulation Controlled by Sensorimotor Desynchronization Induces Robust Increase of Corticospinal Excitability

2016 ◽  
Vol 9 (3) ◽  
pp. 415-424 ◽  
Author(s):  
Dominic Kraus ◽  
Georgios Naros ◽  
Robert Bauer ◽  
Fatemeh Khademi ◽  
Maria Teresa Leão ◽  
...  
Keyword(s):  
Closed Loop ◽  
Corticospinal Excitability ◽  
Brain State ◽  
State Dependent ◽  
Closed Loop Stimulation

Roles of default-mode network and supplementary motor area in human vigilance performance: evidence from real-time fMRI

2013 ◽  
Vol 109 (5) ◽  
pp. 1250-1258 ◽  
Author(s):  
Oliver Hinds ◽  
Todd W. Thompson ◽  
Satrajit Ghosh ◽  
Julie J. Yoo ◽  
Susan Whitfield-Gabrieli ◽  
...  
Keyword(s):  
Real Time ◽  
Default Mode Network ◽  
Human Performance ◽  
Supplementary Motor Area ◽  
Brain Regions ◽  
Motor Area ◽  
Neural Systems ◽  
Brain State ◽  
Default Mode ◽  
Brain States

We used real-time functional magnetic resonance imaging (fMRI) to determine which regions of the human brain have a role in vigilance as measured by reaction time (RT) to variably timed stimuli. We first identified brain regions where activation before stimulus presentation predicted RT. Slower RT was preceded by greater activation in the default-mode network, including lateral parietal, precuneus, and medial prefrontal cortices; faster RT was preceded by greater activation in the supplementary motor area (SMA). We examined the roles of these brain regions in vigilance by triggering trials based on brain states defined by blood oxygenation level-dependent activation measured using real-time fMRI. When activation of relevant neural systems indicated either a good brain state (increased activation of SMA) or a bad brain state (increased activation of lateral parietal cortex and precuneus) for performance, a target was presented and RT was measured. RTs on trials triggered by a good brain state were significantly faster than RTs on trials triggered by a bad brain state. Thus human performance was controlled by monitoring brain states that indicated high or low vigilance. These findings identify neural systems that have a role in vigilance and provide direct evidence that the default-mode network has a role in human performance. The ability to control and enhance human behavior based on brain state may have broad implications.

Brain State-dependent Gain Modulation of Corticospinal Output in the Active Motor System

2019 ◽  
Vol 30 (1) ◽  
pp. 371-381 ◽  
Author(s):  
Georgios Naros ◽  
Tobias Lehnertz ◽  
Maria Teresa Leão ◽  
Ulf Ziemann ◽  
Alireza Gharabaghi
Keyword(s):  
Muscle Activation ◽  
Motor Evoked Potentials ◽  
Brain State ◽  
Robotic Hand ◽  
Response Modulation ◽  
Beta Band ◽  
State Dependent ◽  
Communication Through Coherence ◽  
Oscillatory Cycle ◽  
Hand Opening

Abstract The communication through coherence hypothesis suggests that only coherently oscillating neuronal groups can interact effectively and predicts an intrinsic response modulation along the oscillatory rhythm. For the motor cortex (MC) at rest, the oscillatory cycle has been shown to determine the brain’s responsiveness to external stimuli. For the active MC, however, the demonstration of such a phase-specific modulation of corticospinal excitability (CSE) along the rhythm cycle is still missing. Motor evoked potentials in response to transcranial magnetic stimulation (TMS) over the MC were used to probe the effect of cortical oscillations on CSE during several motor conditions. A brain–machine interface (BMI) with a robotic hand orthosis allowed investigating effects of cortical activity on CSE without the confounding effects of voluntary muscle activation. Only this BMI approach (and not active or passive hand opening alone) revealed a frequency- and phase-specific cortical modulation of CSE by sensorimotor beta-band activity that peaked once per oscillatory cycle and was independent of muscle activity. The active MC follows an intrinsic response modulation in accordance with the communication through coherence hypothesis. Furthermore, the BMI approach may facilitate and strengthen effective corticospinal communication in a therapeutic context, for example, when voluntary hand opening is no longer possible after stroke.

Sign in / Sign up

Export Citation Format

Share Document