Cortico-muscular coupling and motor performance are modulated by 20 Hz transcranial alternating current stimulation (tACS) in Parkinson’s disease

Abstract

Parkinson’s disease (PD) is associated with pathologically altered oscillatory activity. While synchronized oscillations between 13 and 30 Hz are increased within a cortico-subcortical network, cortico-muscular coupling (CMC) is decreased. The present study aims at investigating the effect of non-invasive transcranial alternating current stimulation (tACS) of the primary motor cortex (M1) on motor symptoms and motor-cortical oscillations in PD. In 10 PD patients and 10 healthy control subjects, static isometric contraction, dynamic fast finger tapping, and diadochokinesia of the more severely affected hand were investigated prior to and shortly after tACS of the contralateral M1 at 10 Hz vs. 20 Hz vs. sham. During isometric contraction, neuromagnetic activity was recorded using magnetoencephalography. 20 Hz tACS attenuated beta band CMC during isometric contraction and amplitude variability during finger tapping in PD patients but not in healthy control subjects. 10 Hz tACS yielded no significant after-effects. The present data suggest that PD is associated with pathophysiological alterations which abet a higher responsiveness toward frequency-specific tACS – possibly due to pathologically altered motor-cortical oscillatory synchronization at frequencies between 13 and 30 Hz.

The effect of transcranial alternating current stimulation (tACS) at alpha and beta frequency on motor learning

“…These changes appear to take place within the motor network consisting of the primary motor cortex (M1) and functionally connected cortical and subcortical regions [3][4][5][6][7]. Synchronized oscillatory activity at alpha (8)(9)(10)(11)(12) and beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) Hz) frequencies within and between these brain regions is assumed to facilitate neuronal plasticity thereby promoting motor learning [8,9]. In addition, alpha and beta frequencies may mediate different motor control modes [10].…”

“…Although the exact underlying mechanisms are not well understood, tACS is hypothesized to alter the power of oscillatory brain rhythms by (de) synchronizing neuronal networks in a frequency-dependent manner [18,19]. TACS may entrain endogenous brain oscillations during stimulation [20][21][22][23] and may also be associated with neuroplastic changes outlasting stimulation cessation [20,[24][25][26]. Both tACS and tDCS are suitable to investigate the neurophysiological underpinnings of cognitive and motor processes as well as their potential implementation in neuro(psycho) logical and psychiatric therapy [27,28].…”

Aging induced cortical drive alterations during sleep in rats

“…The corticomuscular coherence (CMC) is an established method for detecting early markers of healthy aging (Kamp et al, 2013), a neurophysiological marker of functional coupling between primary motor cortex and peripheral muscles, a method for quantifying the functional coupling between the motor cortex and contralateral peripheral muscles in frequency domain (Krause et al, 2014;Kristeva et al, 2007;Salenius and Hari, 2003), and the measure of pyramidal system integrity (Kristeva et al, 2007;Mima and Hallett, 1999). CMC plays a crucial role for sensorimotor integration, representing a key mechanism for appropriate motor control (Kamp et al, 2013;Kristeva et al, 2007).…”

REM sleep diversity following the pedunculopontine tegmental nucleus lesion in rat

“…CMC is prominent in the beta frequency band during weak to medium isometric muscle contraction [43]. In contrast to tremor, which has been related to increased oscillatory beta band synchronization [42], the movement slowing (bradykinesia, akinesia, and rigidity) in PD has been related to decreased beta band CMC [44].…”

“…CMC quantitatively reflects the corticomotoneuronal coupling, which can be used as an index of the cortical locomotor drive to particular motor output [39]; represents a binding mechanism between the motor cortex and the corresponding muscle; reflects the conduction of fast pyramidal pathways, and plays a crucial role in sensorimotor integration [41]. CMC is an established method for quantifying the functional coupling between the motor cortex and the contralateral peripheral muscle in the frequency domain and the measure of the integrity of the pyramidal system [42]. CMC is prominent in the beta frequency band during weak to medium isometric muscle contraction [43].…”