Current Change Rate Influences Sensorimotor Cortical Excitability During Neuromuscular Electrical Stimulation

Abstract

Neuromuscular electrical stimulation (NMES) is frequently used in rehabilitation therapy to improve motor recovery. To optimize the stimulatory effect of NMES, the parameters of NMES, including stimulation mode, location, current intensity, and duration, among others have been investigated; however, these studies mainly focused on the effects of changing parameters in the current plateau stage of the NMES cycle, while the impacts on other stages, such as the current rising stage, have yet to be investigated. In this article, we studied the electroencephalograph (EEG) effects during NMES, with different rates of current change in the rising stage, and stable current intensity in the plateau stage. EEG signals (64-channel) were collected from 28 healthy subjects, who were administered with high, medium, or low current change rate (CCR) NMES through a right-hand wrist extensor. Time-frequency analysis and brain source analysis, using the LORETA method, were used to investigate neural activity in sensorimotor cortical areas. The strengths of cortical activity induced by different CCR conditions were compared. NMES with a high CCR activated the sensorimotor cortex, despite the NMES current intensity in the plateau stage lower than the motor threshold. Reduction of the Alpha 2 band (10–13 Hz) event related spectral power (ERSP) during NMES stimulation was significantly enhanced by increasing CCR ( p < 0.05). LORETA-based source analysis demonstrated that, in addition to typical sensory areas, such as primary somatosensory cortex (S1), sensorimotor areas including primary motor cortex (M1), premotor cortex (PMC), and somatosensory association cortex (SAC) were all activated by within threshold NMES. Furthermore, compared with the low CCR condition, cortical activity was significantly enhanced in the S1, M1, and PMC areas under high CCR conditions. This study shows CCR in the NMES rising stage can affect EEG responses in the sensorimotor cortex and suggests that CCR is an important parameter applicable to the optimization of NMES treatment.

Short-Term Suppression of Somatosensory Evoked Potentials and Perceived Sensations in Healthy Subjects Following TENS

“…In the present work, we tested our objective in healthy subjects to allow the inclusion of a sufficiently large and homogeneous subject population. Studies to investigate the effect of novel interventions to modulate neuroplasticity with the later aim to use these for therapeutic purposes in particular patient populations are common [25]- [27]. Our findings, however, ultimately needs to be validated in a clinical setting with phantom limb pain patients.…”

Alteration in Cortical Activity and Perceived Sensation Following Modulated TENS

“…In this paper, we studied healthy subjects intending to include a larger and homogeneous subject population. Investigation of novel intervention effects on healthy populations with a further therapeutic purpose for the patient population has been common strategy [11], [28], [37], [38]. However, future studies on PLP patients with PWM TENS sessions are needed to validate our results.…”

From pulse width modulated TENS to cortical modulation: based on EEG functional connectivity analysis

“…The LORETA computes and estimates the source activities and reduces the dimensionality of the data from the 64-channel electrode space to few cortical regions’ activations ( Pascual-Marqui et al, 1994 ). Several studies have previously validated the consistency of the LORETA algorithm in physiological conditions ( Stern et al, 2006 ; Jiang et al, 2019 ; Zarei et al, 2022 ). The head model was set based on the Montreal Neurological Institute template (MNI-305), including 2,394 voxels with 7 cubic mm spatial resolution.…”