Event-Related Desynchronization During Mirror Visual Feedback: A Comparison of Older Adults and People After Stroke.

Event-related desynchronization (ERD), as a proxy for mirror neuron activity, has been used as a neurophysiological marker for motor execution after mirror visual feedback (MVF). Using EEG, this study investigated ERD upon the immediate effects of single-session MVF in unimanual arm movements compared with the ERD effects occurring without a mirror, in two groups: stroke patients with left hemiplegia and their healthy counterparts. During EEG recordings, each group performed one session of mirror therapy training in three task conditions: with a mirror, with no mirror, and with a covered mirror. An asymmetry index was calculated from the subtraction of the event-related spectrum perturbations between the C3 and C4 electrodes located over the sensorimotor cortices contralateral and ipsilateral to the moved arm. Results of the effect of task versus group in contralateral and ipsilateral motor areas showed that there was a significant effect of task condition at the contralateral motor area in the high beta band (17-35 Hz) at C3. High beta ERD showed that the suppression was greater over the contralateral hemisphere than it was over the ipsilateral hemisphere in both study groups. The magnitude of low beta (12-16 Hz) ERD in patients with stroke was more suppressed in contralesional C3 under the no mirror compared to that of the covered mirror and similarly more suppressed in ipsilesional C4 ERD under the no mirror compared to that of the mirror condition. The correlation analysis revealed that the magnitude of ERSP power correlated significantly with arm severity in the low and high beta bands in patients with stroke, and a higher asymmetry index in the low beta band was associated with higher arm functioning under the no-mirror condition. There was a shift in sensorimotor ERD toward the contralateral hemisphere as induced by MVF accompanying unimanual movement in both stroke patients and healthy controls. The use of ERD in the low beta band as a neurophysiological marker to indicate the relationships between the amount of MVF-induced ERD attenuation and motor severity, and the outcome indicator for improving stroke patients' neuroplasticity in clinical trials using MVF are warranted to be explored in the future.

Non-invasive brain stimulation for posttraumatic stress disorder: a systematic review and meta-analysis.

Approximately 7-9% of people develop posttraumatic stress disorder in their lifetime, but standard pharmacological treatment or psychotherapy shows a considerable individual variation in their effectiveness. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) hold promise for the treatment of posttraumatic stress disorder. The objective of this meta-analysis was to summarize the existing evidence on the therapeutic effects of these brain stimulation treatments on posttraumatic core symptoms. We systematically retrieved articles published between 1st January 2000 and 1st January 2020 comparing the effects of active with sham stimulation or no intervention in posttraumatic patients from eight databases. Random-effects model was used for meta-analysis. Meta-regression and subgroup meta-analysis was performed to investigate the influence of stimulation dose and different stimulation protocols, respectively. 20 studies were included in this review, where of 11 randomized controlled trials were subjected to quantitative analysis. Active stimulation demonstrated significant reductions of core posttraumatic symptoms with a large effect size (Hedge's g = -0.975). Subgroup analysis showed that both excitatory and inhibitory rTMS of the right dorsolateral prefrontal cortex led to symptom reductions with a large (Hedges' g = -1.161, 95% CI, -1.823 to -0.499; p = 0.015) and medium effect size (Hedges' g = -0.680, 95% CI: -0.139 to -0.322; p ≤ 0.001) respectively. Results further indicated significant durability of symptom-reducing effects of treatments during a two to four weeks period post stimulation (Hedges' g = -0.909, 95% CI: -1.611 to -0.207; p = 0.011). rTMS of the right dorsolateral prefrontal cortex appears to have a positive effect in reducing core symptoms in patients with posttraumatic stress disorder.

Effects of repetitive transcranial magnetic stimulation (rTMS) on craving and substance consumption in patients with substance dependence: a systematic review and meta-analysis.

BACKGROUND AND AIMS: Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as an intervention for treating substance dependence. We aimed to assess evidence of the anti-craving and consumption-reducing effects of rTMS in patients with alcohol, nicotine and illicit drug dependence. METHODS: A systematic review and meta-analysis of 26 randomized controlled trials (RCTs) published from January 2000 to October 2018 that investigated the effects of rTMS on craving and substance consumption in patients with nicotine, alcohol and illicit drug dependence (n = 748). Craving, measured using self-reported questionnaires or visual analog scale, and substance consumption, measured using self-report substance intake or number of addiction relapse cases, were considered as primary and secondary outcomes, respectively. Substance type, study design and rTMS parameters were used as the independent factors in the meta-regression. RESULTS: Results showed that excitatory rTMS of the left dorsolateral pre-frontal cortex (DLPFC) significantly reduced craving [Hedges' g = -0.62; 95% confidence interval (CI) = -0.89 to -0.35; P < 0.0001], compared with sham stimulation. Moreover, meta-regression revealed a significant positive association between the total number of stimulation pulses and effect size among studies using excitatory left DLPFC stimulation (P = 0.01). Effects of other rTMS protocols on craving were not significant. However, when examining substance consumption, excitatory rTMS of the left DLPFC and excitatory deep TMS (dTMS) of the bilateral DLPFC and insula revealed significant consumption-reducing effects, compared with sham stimulation. CONCLUSION: Excitatory repetitive transcranial magnetic stimulation of the dorsolateral pre-frontal cortex appears to have an acute effect on reducing craving and substance consumption in patients with substance dependence. The anti-craving effect may be associated with stimulation dose.

The Activation of the Mirror Neuron System during Action Observation and Action Execution with Mirror Visual Feedback in Stroke: A Systematic Review.

Objective: To evaluate the concurrent and training effects of action observation (AO) and action execution with mirror visual feedback (MVF) on the activation of the mirror neuron system (MNS) and its relationship with the activation of the motor cortex in stroke individuals. Methods: A literature search using CINAHL, PubMed, PsycINFO, Medline, Web of Science, and SCOPUS to find relevant studies was performed. Results: A total of 19 articles were included. Two functional magnetic resonance imaging (fMRI) studies reported that MVF could activate the ipsilesional primary motor cortex as well as the MNS in stroke individuals, whereas two other fMRI studies found that the MNS was not activated by MVF in stroke individuals. Two clinical trials reported that long-term action execution with MVF induced a shift of activation toward the ipsilesional hemisphere. Five fMRI studies showed that AO activated the MNS, of which, three found the activation of movement-related areas. Five electroencephalography (EEG) studies demonstrated that AO or MVF enhanced mu suppression over the sensorimotor cortex. Conclusions: MVF may contribute to stroke recovery by revising the interhemispheric imbalance caused by stroke due to the activation of the MNS. AO may also promote motor relearning in stroke individuals by activating the MNS and motor cortex.