scholarly journals Systematic examination of low-intensity ultrasound parameters on human motor cortex excitability and behavior

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Anton Fomenko ◽  
Kai-Hsiang Stanley Chen ◽  
Jean-François Nankoo ◽  
James Saravanamuttu ◽  
Yanqiu Wang ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Cortical Inhibition ◽  
Transcranial Ultrasound ◽  
Human Motor Cortex ◽  
Low Intensity ◽  
Visuomotor Task ◽  
Motor Cortex Excitability ◽  
And Behavior

Low-intensity transcranial ultrasound (TUS) can non-invasively modulate human neural activity. We investigated how different fundamental sonication parameters influence the effects of TUS on the motor cortex (M1) of 16 healthy subjects by probing cortico-cortical excitability and behavior. A low-intensity 500 kHz TUS transducer was coupled to a transcranial magnetic stimulation (TMS) coil. TMS was delivered 10 ms before the end of TUS to the left M1 hotspot of the first dorsal interosseous muscle. Varying acoustic parameters (pulse repetition frequency, duty cycle, and sonication duration) on motor-evoked potential amplitude were examined. Paired-pulse measures of cortical inhibition and facilitation, and performance on a visuomotor task was also assessed. TUS safely suppressed TMS-elicited motor cortical activity, with longer sonication durations and shorter duty cycles when delivered in a blocked paradigm. TUS increased GABAA-mediated short-interval intracortical inhibition and decreased reaction time on visuomotor task but not when controlled with TUS at near-somatosensory threshold intensity.

Evidence for high-fidelity timing-dependent synaptic plasticity of human motor cortex

2013 ◽  
Vol 109 (1) ◽  
pp. 106-112 ◽  
Author(s):  
R. F. H. Cash ◽  
F. L. Mastaglia ◽  
G. W. Thickbroom
Keyword(s):  
Motor Cortex ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Single Pulse ◽  
Cortical Inhibition ◽  
Membrane Excitability ◽  
Human Motor Cortex ◽  
Excitatory Transmission ◽  
Resting Motor Threshold ◽  
Human Motor

A single transcranial magnetic stimulation (TMS) pulse typically evokes a short series of spikes in corticospinal neurons [known as indirect (I)-waves] which are thought to arise from transynaptic input. Delivering a second pulse at inter-pulse intervals (IPIs) corresponding to the timing of these I-waves leads to a facilitation of the response, and if stimulus pairs are delivered repeatedly, a persistent LTP-like increase in excitability can occur. This has been demonstrated at an IPI of 1.5 ms, which corresponds to the first I-wave interval, in an intervention referred to as ITMS (I-wave TMS), and it has been argued that this may have similarities with timing-dependent plasticity models. Consequently, we hypothesized that if the second stimulus is delivered so as not to coincide with I-wave timing, it should lead to LTD. We performed a crossover study in 10 subjects in which TMS doublets were timed to coincide (1.5-ms IPI, ITMS1.5) or not coincide (2-ms IPI, ITMS2) with I-wave firing. Single pulse motor-evoked potential (MEP) amplitude, resting motor threshold (RMT), and short-interval cortical inhibition (SICI) were measured from the first dorsal interosseous (FDI) muscle. After ITMS1.5 corticomotor excitability was increased by ∼60% for 15 min ( P < 0.05) and returned to baseline by 20 min. Increasing the IPI by just 500 μs to 2 ms reversed the aftereffect, and MEP amplitude was significantly reduced (∼35%, P < 0.05) for 15 min before returning to baseline. This reduction was not associated with an increase in SICI, suggesting a reduction in excitatory transmission rather than an increase in inhibitory efficacy. RMT also remained unchanged, suggesting that these changes were not due to changes in membrane excitability. Amplitude-matching ITMS2 did not modulate excitability. The results are consistent with timing-dependent synaptic LTP/D-like effects and suggest that there are plasticity mechanisms operating in the human motor cortex with a temporal resolution of the order of a few hundreds of microseconds.

Late Cortical Disinhibition in Human Motor Cortex: A Triple-Pulse Transcranial Magnetic Stimulation Study

2010 ◽  
Vol 103 (1) ◽  
pp. 511-518 ◽  
Author(s):  
R. F. H. Cash ◽  
U. Ziemann ◽  
K. Murray ◽  
G. W. Thickbroom
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Intracortical Inhibition ◽  
Human Motor Cortex ◽  
Acid Type ◽  
Human Motor

In human motor cortex transcranial magnetic stimulation (TMS) has been used to identify short-interval intracortical inhibition (SICI) corresponding to γ-aminobutyric acid type A (GABAA) effects and long-interval intracortical inhibition (LICI) and the cortical silent period (SP) corresponding to postsynaptic GABAB effects. Presynaptic GABAB effects, corresponding to disinhibition, can also be identified with TMS and have been shown to be acting during LICI by measuring SICI after a suprathreshold priming stimulus (PS). The duration of disinhibition is not certain and, guided by studies in experimental preparations, we hypothesized that it may be longer-lasting than postsynaptic inhibition, leading to a period of late cortical disinhibition and consequently a net increase in corticospinal excitability. We tested this first by measuring the motor-evoked potential (MEP) to a test stimulus (TS), delivered after a PS at interpulse intervals (IPIs) ≤300 ms that encompassed the period of PS-induced LICI and its aftermath. MEP amplitude was initially decreased, but then increased at IPIs of 190–210 ms, reaching 160 ± 17% of baseline 200 ms after PS ( P < 0.05). SP duration was 181 ± 5 ms. A second experiment established that the onset of the later period of increased excitability correlated with PS intensity ( r2 = 0.99) and with the duration of the SP ( r2 = 0.99). The third and main experiment demonstrated that SICI was significantly reduced in strength at all IPIs ≤220 ms after PS. We conclude that TMS-induced LICI is associated with a period of disinhibition that is at first masked by LICI, but that outlasts LICI and gives rise to a period during which disinhibition predominates and net excitability is raised. Identification of this late period of disinhibition in human motor cortex may provide an opportunity to explore or modulate the behavior of excitatory networks at a time when inhibitory effects are restrained.

scholarly journals Homeostatic Modulation of Stimulation-Dependent Plasticity in Human Motor Cortex

2011 ◽  
pp. S107-S112 ◽  
Author(s):  
N. V. ILIĆ ◽  
S. MILANOVIĆ ◽  
J. KRSTIĆ ◽  
Đ. D. BAJEC ◽  
M. GRAJIĆ ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Motor Cortex ◽  
Motor Evoked Potential ◽  
Single Pair ◽  
Post Intervention ◽  
Human Motor Cortex ◽  
Motor Cortex Excitability ◽  
Human Motor ◽  
Plastic Changes ◽  
Complex Relationships

Since recently, it is possible, using noninvasive cortical stimulation, such as the protocol of paired associative stimulation (PAS), to induce the plastic changes in the motor cortex, in humans that mimic Hebb's model of learning. Application of TMS conjugated with peripheral electrical stimulation at strictly coherent temporal manner lead to convergence of inputs in the sensory-motor cortex, with the consequent synaptic potentiation or weakening, if applied repetitively. However, when optimal interstimulus interval (ISI) for induction of LTP-like effects is applied as a single pair, Motor evoked potential (MEP) amplitude inhibition is observed, the paradigm known as short-latency afferent inhibition (SLAI). Aiming to resolve this paradox, PAS protocols were applied, with 200 repetitions of TMS pulses paired with median nerve electrical stimulation, at ISI equal to individual latencies of evoked response of somatosensory cortex (N20) (PASLTP), and at ISI of N20 shortened for 5 msec (PASLTD) – protocols that mimic LTP-like changes in the human motor cortex. MEP amplitudes before, during and after interventions were measured as an indicator based on output signals originating from the motor system. Post-intervention MEP amplitudes following the TMS protocols of PASLTP and PASLTD were facilitated and depressed, respectively, contrary to MEP amplitudes during intervention. During PASLTP MEP amplitudes were significantly decreased in case of PASLTP, while in the case of PASLTD an upward trend was observed. In conclusions, a possible explanation for the seemingly paradoxical effect of PAS can be found in the mechanism of homeostatic modulation of plasticity. Those findings indicate the existence of complex relationships in the development of plasticity induced by stimulation, depending on the level of the previous motor cortex excitability.

P029 Direct evaluation of intra-cortical inhibition and facilitation balance in human motor cortex: an EEG-paired pulse TMS study

2008 ◽  
Vol 119 ◽  
pp. S78
Author(s):  
Florinda Ferreri ◽  
Patrizio Pasqualetti ◽  
David Ponzo ◽  
Sara Maatta ◽  
Fabio Ferrarelli ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Cortical Inhibition ◽  
Direct Evaluation ◽  
Human Motor Cortex ◽  
Paired Pulse ◽  
Human Motor

P025 Minocycline has acute inhibitory effects on human motor cortex excitability

2008 ◽  
Vol 119 ◽  
pp. S77
Author(s):  
Nicolas Lang ◽  
Daniella Terney ◽  
Holger Rothkegel ◽  
Andrea Antal ◽  
Walter Paulus
Keyword(s):  
Motor Cortex ◽  
Inhibitory Effects ◽  
Human Motor Cortex ◽  
Motor Cortex Excitability ◽  
Human Motor

scholarly journals High Gamma and Beta Temporal Interference Stimulation in the Human Motor Cortex Improves Motor Functions

2022 ◽  
Vol 15 ◽  
Author(s):  
Ru Ma ◽  
Xinzhao Xia ◽  
Wei Zhang ◽  
Zhuo Lu ◽  
Qianying Wu ◽  
...  
Keyword(s):  
Reaction Time ◽  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Reaction Time Task ◽  
Promoting Effect ◽  
Motor Functions ◽  
Human Motor Cortex ◽  
Time Task ◽  
Motor Cortex Excitability ◽  
Human Motor

Background: Temporal interference (TI) stimulation is a new technique of non-invasive brain stimulation. Envelope-modulated waveforms with two high-frequency carriers can activate neurons in target brain regions without stimulating the overlying cortex, which has been validated in mouse brains. However, whether TI stimulation can work on the human brain has not been elucidated.Objective: To assess the effectiveness of the envelope-modulated waveform of TI stimulation on the human primary motor cortex (M1).Methods: Participants attended three sessions of 30-min TI stimulation during a random reaction time task (RRTT) or a serial reaction time task (SRTT). Motor cortex excitability was measured before and after TI stimulation.Results: In the RRTT experiment, only 70 Hz TI stimulation had a promoting effect on the reaction time (RT) performance and excitability of the motor cortex compared to sham stimulation. Meanwhile, compared with the sham condition, only 20 Hz TI stimulation significantly facilitated motor learning in the SRTT experiment, which was significantly positively correlated with the increase in motor evoked potential.Conclusion: These results indicate that the envelope-modulated waveform of TI stimulation has a significant promoting effect on human motor functions, experimentally suggesting the effectiveness of TI stimulation in humans for the first time and paving the way for further explorations.

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