Effects of Transcranial Alternating Current Stimulation on the Primary Motor Cortex by Online Combined Approach with Transcranial Magnetic Stimulation

Shpektor, Anna; Nazarova, Maria; Feurra, Matteo

doi:10.3791/55839

Cited by 8 publications

(10 citation statements)

References 28 publications

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“…The majority of tACS studies using TMS-induced MEPs to measure effects of tACS neuromodulation demonstrated prominent frequency-specific online effects 6 , 7 , 31 , 32 . For instance, 20 Hz (beta-band) stimulation increased corticospinal excitability (measured as TMS-induced MEPs amplitude) at rest, while other frequencies (i.e.…”

Section: Introductionmentioning

confidence: 99%

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

Pozdniakov

Vorobiova

Galli

et al. 2021

Sci Rep

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Transcranial 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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Section: Introductionmentioning

confidence: 99%

“…In Experiment 1, we tested online effects of tACS on the motor corticospinal output at rest by using a combined single pulse TMS-tACS approach 6 , 7 , 31 . Our dependent variable was the amplitude of TMS-induced MEPs recorded from the contralateral first dorsal interosseous muscle (FDI) 49 .…”

Section: Introductionmentioning

confidence: 99%

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

Pozdniakov

Vorobiova

Galli

et al. 2021

Sci Rep

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“…Транскраниальная магнитная стимуляция (ТМС) , транскраниальной электрической стимуляцией (Shpektor, Nazarova, & Feurra, 2017) и др. ).…”

Section: аннотацияunclassified

Активность-Зависимая ТМС – Совмещение Пространственной И Временной Информации

Новиков¹,

Nazarova²,

Решетников³

et al. 2020

Preprint

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Транскраниальная магнитная стимуляция (ТМС) является средством модулирующего воздействия на мозг для его изучения в норме и при патологии. Важной проблемой, ограничивающей применение ТМС, является высокая вариативность ее эффектов. Становится очевидным, что эффект ТМС протокола – это не только свойство самого протокола, но следствие взаимодействий ТМС с индивидуальными особенностями нервной системы и ее текущим функциональным состоянием. Необходимо создание ТМС подходов, учитывающих текущее нейрональное состояние – подходов состояние/активность-зависимой ТМС. В работе представлено программное обеспечение, объединяющее возможности нейронавигации и учета текущего функционального состояния при ТМС. Подача стимулов происходит автоматически при выполнении ряда заданных условий (например, начало движения, точное положение индуктора). Задержка запуска ТМС протестирована в эксперименте со стимуляцией по условию начала сокращения мышцы. Разработка технического решения для навигационной активность-зависимой ТМС позволит вывести этот метод стимуляции мозга на новый уровень персонифицированного использования.

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“…Also, it is unclear whether corticospinal bursts at higher and lower frequencies are produced by independent oscillatory intracortical circuits with different characteristics, as suggested by modeling studies 8 , or rather reflect the activity of a single neuronal generator able to discharge at harmonically-related frequencies (667 and 333 Hz). A possible approach to explore this issue is to take advantage of the combined stimulation of the motor cortex with TMS and transcranial alternating current stimulation (tACS) [9][10][11][12][13][14][15][16] . tACS is able to cause coherent changes in the firing probability and thereby timing of neuronal populations, thus entraining brain activity [17][18][19] .…”

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confidence: 99%

Detecting cortical circuits resonant to high-frequency oscillations in the human primary motor cortex: a TMS-tACS study

Guerra

Ranieri

Falato

et al. 2020

Sci Rep

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Corticospinal volleys evoked by transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) consist of high-frequency bursts (≈667 and ≈333 Hz). However, intracortical circuits producing such corticospinal high-frequency bursts are unknown. We here investigated whether neurons activated by single TMS pulses over M1 are resonant to high-frequency oscillations, using a combined transcranial alternating current stimulation (tACS)-TMS approach. We applied 667, 333 Hz or sham-tACS and, concurrently, we delivered six single-pulse TMS protocols using monophasic or biphasic pulses, different stimulation intensities, muscular states, types and orientations of coils. We recorded motor evoked potentials (MEPs) before, during and after tACS. 333 Hz tACS facilitated MEPs evoked by biphasic TMS through a figure-of-eight coil at active motor threshold (AMT), and by monophasic TMS with anteriorto-posterior-induced current in the brain. 333 Hz tACS also facilitated MEPs evoked by monophasic TMS through a circular coil at AMT, an effect that weakly persisted after the stimulation. 667 Hz tACS had no effects. 333 Hz, but not 667 Hz, tACS may have reinforced the synchronization of specific neurons to high-frequency oscillations enhancing this activity, and facilitating MEPs. Our findings suggest that different bursting modes of corticospinal neurons are produced by separate circuits with different oscillatory properties. Corticospinal neurons (CSNs) of the mammalian brain show a high frequency (≈667 Hz) burst of activity in response to transcranial electric (TES) and magnetic (TMS) stimulation. These stereotyped bursts of activity can be recorded from the surface of the high cervical cord and reflect the spiking of a large number of corticospinal axons 1-5. Recently, Maier et al. 6 recorded the responses of single corticospinal axons together with volleys from the surface of the cervical cord after intracortical stimulation in monkey and showed that individual axons fire repetitively at the high frequency revealed by surface recordings, thus demonstrating that bursts originate from the repetitive synchronous discharge of CSNs. They also found that while most of the corticospinal axons discharged at around 600 Hz, there were other axons responding at lower frequencies 6. In humans, bursts of corticospinal activity with different frequencies can be recorded by cervical epidural electrodes after TMS over the motor cortex 5. This descending bursting activity is influenced by the direction of the current flowing across the central sulcus. The more commonly used posterior-to-anterior (PA)-induced current in the brain (perpendicular to the central sulcus) preferentially evokes the 667 Hz repetitive discharge. However, when the orientation of the induced current is reversed (anterior-to-posterior in the brain; AP) or when stimulation is performed using a biphasic TMS that combines sequentially both directions of stimulation (a PA induced current followed by an AP induced current), the output changes with less synchronized vol...

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Effects of Transcranial Alternating Current Stimulation on the Primary Motor Cortex by Online Combined Approach with Transcranial Magnetic Stimulation

Cited by 8 publications

References 28 publications

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

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

Активность-Зависимая ТМС – Совмещение Пространственной И Временной Информации

Detecting cortical circuits resonant to high-frequency oscillations in the human primary motor cortex: a TMS-tACS study

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