Anodal Stimulation Research Articles

Preclinical Validation of Electrodes for Single Anodal Transcranial Direct Current Stimulation on Rat Model With Chronic Stress-Induced Depression

Transcranial direct current stimulation (tDCS) is an effective and safe non-invasive brain stimulation (NIBS) procedures to modulate neuronal excitability. The present preclinical study was carried out to validate the impact of the innovative high definition fabricated spiking Au/AgCI electrodes via non-invasive tDCS procedure on rat model with depression-like behaviour. In present study, chronic stress induced depression like behaviour rat model was developed over a period of 14-days. Further, the after-effects of NIBS procedures were investigated by providing a tDCS dose (2.00mA × 5.00minutes) by placing the electrodes on the interested region of the rat brain. The current study was performed in healthy rats, control rats with depression-like behaviour, and tDCS treated rats, which were used to examine the differential after-effects of tDCS dose. After single tDCS dose, a significant increase in average band power of electroencephalogram (EEG) has been observed (F(2, 15) = 8.376; P = 0.0036) alongside a significant increase in the glutamate level of hippocampus (F(2, 15) = 8.919; P = 0.0028), a significant reduction in immobility time (F(2, 15) = 7.552; P = 0.0054), and a significant increase in the percentage sucrose intake has been observed (F(2,15) = 5.941; P = 0.0126). Additionally, immunohistochemistry (IHC) showed a significant increase in theIba1 protein expression in microglia cell in the both cortex and hippocampus region (P < 0.05). Hence, the fabricated electrodes can deliver a tDCS dose that can penetrate up to the cortex and hippocampus regions from the surface of brain non-invasively within tolerable and safety limits.

Effects of high-definition transcranial direct current stimulation on implicit emotion regulation of social pain in healthy individuals

BackgroundImplicit emotion regulation (ER), a form of ER, is essential for protecting mental health in the process of social interaction. Both the ventrolateral prefrontal cortex (VLPFC) and the dorsolateral prefrontal cortex (DLPFC) have been shown to be involved in ER processes, including explicit ER of social pain, but whether they play a role in implicit ER is unclear. MethodsWe investigated whether anodal high-definition transcranial direct current stimulation (HD-tDCS) of the right VLPFC (rVLPFC) or the right DLPFC (rDLPFC) influences implicit ER. In total, 63 healthy participants completed an emotion priming task, which measures the implicit ER of social pain, before and after receiving active or sham HD-tDCS (2 mA for 20 min, 10 consecutive days). Event-related potentials (ERPs) were recorded during task performance. ResultsCombined with the results of the behavioral and electrophysiological indices indicated that stimulation of both the rVLPFC and the rDLPFC by anodic HD-tDCS could significantly reduce the affective responses caused by social exclusion. The further results also suggested that rDLPFC activation may contribute to promoting the involvement of early cognitive resources in the implicit ER process of social pain, thus helping to reduce the subjective negative experience of individuals. LimitationsThere were no dynamic interactive emotional stimuli to induce social pain, and only static images of social exclusion were used. ConclusionOur study provides cognitive and neurological evidence that expands our knowledge of the role of the rDLPFC and the rVLPFC in social ER. It can also serve as a reference for targeted intervention of implicit ER in social pain.

Modulating Phonological Working Memory With Anodal High-Definition Transcranial Direct Current Stimulation to the Anterior Portion of the Supplementary Motor Area.

Phonological working memory is key to vocabulary acquisition, spoken word recognition, real-time language processing, and reading. Transcranial direct current stimulation, when coupled with behavioral training, has been shown to facilitate speech motor output processes, a key component of nonword repetition, the primary task used to assess phonological working memory. In this study, we examined the efficacy of combining overt nonword repetition training with anodal high-definition transcranial direct current stimulation (HD tDCS) to the presupplementary motor area (preSMA) to enhance nonword repetition. This study investigated whether 20 min of active or sham anodal HD tDCS targeting preSMA concurrently with a nonword repetition task differentially impacted nonword repetition ability. Twenty-eight neurotypical college-age adults (18-25 years; 19 females, eight males, one nonbinary) completed a 20-min nonword repetition training task where they received either active or sham 1-mA anodal HD tDCS to the preSMA while overtly repeating a list of four-, five-, six-, and seven-syllable English-like nonwords presented in a random order. Whole nonword accuracy and error patterns (phoneme and syllable) were measured prior to and following training. Following training, both groups showed a decrease in nonword repetition accuracy. The drop in performance was significantly greater for the active stimulation group compared to the sham stimulation group at the four-syllable nonword length. The findings suggest that targeting the speech motor component of nonword repetition through overt training and HD tDCS to the preSMA does not enhance phonological working memory ability.

Transcranial direct current stimulation alters the process of reward processing in children with ADHD: Evidence from cognitive modeling

BackgroundThe ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are the neural underpinnings of reward processing, which is impaired in individuals with attention deficit hyperactivity disorder (ADHD). In the present study, we aimed to explore the impact of the vmPFC and the dlPFC regulation on reward processing. MethodsTwenty-six children with ADHD performed the balloon analogue risk-taking task (BART) and chocolate delay discounting task (CDDT) during five different sessions of transcranial direct current stimulation (tDCS), separated by a one-week interval: anodal left dlPFC/cathodal right vmPFC, the reversed electrode positioning, anodal left dlPFC stimulation with extracranial return electrode, anodal right vmPFC stimulation with extracranial return electrodes, and sham stimulation. Four-parameter and constant-sensitivity models were used to model the data. ResultsIn the BART, anodal dlPFC/cathodal vmPFC stimulation facilitated conservative decision making, anodal tDCS over dlPFC with extracranial return electrode increased positive beliefs about the explosion of a balloon, and anodal vmPFC/cathodal dlPFC stimulation reduced ongoing learning in the process of decision making. In the CDDT, anodal vmPFC stimulation with extracranial return electrode decreased impatience in the process of the task. ConclusionThese results suggest a role of the left dlPFC and right vmPFC in the outcome of decision making and the process of risky decision making and delay discounting.

Transcranial direct-current stimulation enhances Pavlovian tendencies during intermittent loss of control.

Pavlovian bias is an innate motivational tendency to approach rewards and remain passive in the face of punishment. The relative reliance on Pavlovian valuation has been found to increase when the perceived control over environmental reinforcers is compromised, leading to behavior resembling learned helplessness (LH). Sixty healthy young adults underwent a Go-NoGo reinforcement learning task and received anodal high-definition transcranial direct current stimulation (HD-tDCS) over the medial prefrontal/dorsal anterior cingulate cortex in our randomized, double-blind, sham- controlled study. Furthermore, we evaluated changes in cue-locked mid-frontal theta power derived from simultaneous electroencephalography (EEG). We hypothesized that active stimulation would reduce Pavlovian bias during manipulation of outcome controllability, and the effect would be accompanied by stronger mid-frontal theta activity, representing arbitration between choice strategies in favor of instrumental relative to Pavlovian valuation. We found a progressive decrease in Pavlovian bias during and after loss of control over feedback. Active HD-tDCS counteracted this effect while not affecting the mid-frontal theta signal. The results were at odds with our hypotheses but also with previous findings reporting LH-like patterns during and after loss of control without brain stimulation. The discrepancy may be related to different protocols for the controllability manipulation. We argue that the subjective evaluation of task controllability is crucial in mediating the balance between Pavlovian and instrumental valuation during reinforcement learning and that the medial prefrontal/dorsal anterior cingulate cortex is a key region in this respect. These findings have implications for understanding the behavioral and neural underpinnings of LH in humans.

Anodal Transcranial Direct Current Stimulation over the Right Dorsolateral Prefrontal Cortex Boosts Decision Making and Functional Impulsivity in Female Sports Referees.

We investigated the effect of anodal transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (rDLPFC) on the sensitive decision making of female team sports referees. Twenty-four female referees voluntarily participated in this randomized, double-blind, crossover, and sham-controlled study. In three different sessions, participants received either anodal (a-tDCS; anode (+) over F4, cathode (-) over the supraorbital region (SO)), cathodal (c-tDCS; -F4/+SO), or sham tDCS (sh-tDCS) in a randomized and counterbalanced order. a-tDCS and c-tDCS were applied with 2 mA for 20 min. In sh-tDCS, the current was turned off after 30 s. Before and after tDCS, participants performed the computerized Iowa Gambling Task (IGT) and Go/No Go impulsivity (IMP) tests. Only a-tDCS improved IGT and IMP scores from pre to post. The delta (Δ = post-pre) analysis showed a significantly higher ΔIGT in a-tDCS compared to c-tDCS (p = 0.02). The ΔIMP was also significantly higher in a-tDCS compared to sh-tDCS (p = 0.01). Finally, the reaction time decreased significantly more in a-tDCS (p = 0.02) and sh-tDCS (p = 0.03) than in c-tDCS. The results suggest that the a-tDCS improved factors related to sensitive decision making in female team sports referees. a-tDCS might be used as an ergogenic aid to enhance decision performance in female team sports referees.

Remotely supervised at-home tDCS for veterans with persistent post-traumatic headache: a double-blind, sham-controlled randomized pilot clinical trial.

Currently, there are no FDA approved therapies for persistent post-traumatic headache (PPTH) secondary to traumatic brain injury (TBI). As such neither headache nor TBI specialists have an effective means to manage PPTH. Thus, the objective of the present pilot trial was to evaluate the feasibility and preliminary efficacy of a four-week at-home remotely supervised transcranial direct current stimulation (RS-tDCS) intervention for veterans with PPTH. Twenty-five (m = 46.6 ± 8.7 years) veterans with PPTH were randomized into two groups and received either active (n = 12) or sham (n = 13) RS-tDCS, with anodal stimulation over left dlPFC and cathodal over occipital pole. Following a four-week baseline, participants completed 20-sessions of active or sham RS-tDCS with real-time video monitoring over a period of four-weeks. Participants were assessed again at the end of the intervention and at four-weeks post-intervention. Primary outcomes were overall adherence rate (feasibility) and change in moderate-to-severe headache days per month (efficacy). Secondary outcomes were changes in total number of headache days, and PPTH-related functional outcomes. Adherence rate was high with 88% of participants (active = 10/12; sham = 12/13) fully completing tDCS interventions. Importantly, there was no significant difference in adherence between active and sham groups (p = 0.59). Moderate-to-severe headache days were significantly reduced within the active RS-tDCS group (p = 0.004), compared to sham during treatment (-2.5 ± 3.5 vs. 2.3 ± 3.4), and 4-week follow-up (-3.9 ± 6.4 vs. 1.2 ± 6.5). Total number of headache days was significantly reduced within the active RS-tDCS (p = 0.03), compared to sham during-treatment (-4.0 ± 5.2 vs. 1.5 ± 3.8), and 4-week follow-up (-2.1 ± 7.2 vs. -0.2 ± 4.4). The current results indicate our RS-tDCS paradigm provides a safe and effective means for reducing the severity and number of headache days in veterans with PPTH. High treatment adherence rate and the remote nature of our paradigm indicate RS-tDCS may be a feasible means to reduce PPTH, especially for veterans with limited access to medical facilities.Clinical Trial Registration: ClinicalTrials.gov, identifier [NCT04012853].

The Involvement of Broca’s Area and Its Right-Hemispheric Homologue in Acquiring Abstract and Concrete Semantics: Transcranial Direct-Current Stimulation Study

The study compared effects of transcranial direct current stimulation (tDCS) of Broca’s area and of its right-hemispheric homologue on the acquisition of novel concrete and abstract words. Word/concept acquisition was achieved through reading sets of sentences, which incorporated novel words, gradually revealing their meaning through context. Before the learning session, a 15-minute anodal or cathodal stimulation of one of the target areas was applied. Lexical decision task was used to assess the learning outcomes immediately after the learning session and 24 hours later. The results showed a larger number of correct responses after right-hemispheric tDCS, in comparison with that of Broca’s area in the left hemisphere. These results suggest that the right-hemispheric counterpart of Broca’s areas is involved in the processing and acquisition of new concrete and abstract semantics. Furthermore, they demonstrate facilitatory effects of tDCS on the processes of overnight consolidation of newly formed word memory traces.

PO-04-058 AN UNUSUAL CASE OF ATRIAL SENSING BY A DEFIBRILLATOR LEAD CAUSING ASYSTOLE

Integrated bipolar transvenous defibrillator leads (IL) offer advantages over dedicated bipolar defibrillator leads (BL): IL have a simplified construction and are less prone to anodal stimulation. A potential problem for the IL is oversensing due to a large sensing area. We present a case of an IL with intermittent asystole treated by exchange of the IL for a BL. N/A N/A A 51-year-old female with hypertrophic cardiomyopathy received a Boston Scientific (BS) dual chamber ICD in 2011 with a IL (BS 0185) for VT and intermittent heart block. In May 2022, she underwent an uncomplicated generator change. Six months later she presented with presyncopal events. Hospital telemetry showed DDD pacing with intermittent lack of ventricular output and no escape rhythm. There was no evidence of lead dislodgement and manipulation of the pocket did not reproduce an event. Device interrogation showed normal and stable lead thresholds and impedances. She was now pacemaker dependent. Spontaneous asystole was captured by the intracardiac electrogram (IEGM) demonstrating atrial far-field sensing with inhibition of RV pacing. Decreasing the RV sensitivity did not resolve the issue. We urgently turned on “Electrocautery Protection Mode” (DOO 60 and V Tachy Mode-OFF) restoring 100% dual chamber pacing and capture. We suspected that atrial far field sensing was due to the IL design. The size and position of the sensing anode can allow for far-field atrial sensing and inhibition of RV output. Intraoperative manipulation and testing of the generator and leads showed normal parameters. The patient underwent extraction of the IL, and a BL (Medtronic 6935m) was implanted. A BL was selected due to its distal, and closely spaced, pace/sense electrode design. The device was reprogrammed to her prior settings with no further episodes or symptoms occurring. This case shows an unusual problem with the IL design. Capturing this event by IEGM was diagnostic. Reducing the IL sensitivity is not optimal, making the patient vulnerable to undersensing of ventricular fibrillation. Discussion with BS Technical Services confirms that this phenomenon is rarely seen and more likely to occur in patients with a small RV. We suspect that changes in body habitus, a small RV cavity, and progression of heart block exposed the problem years after implant. Exchange of a IL with a BL provided a lasting solution.

Innovative Therapy Combining Neck Muscle Vibration and Transcranial Direct Current Stimulation in Association with Conventional Rehabilitation in Left Unilateral Spatial Neglect Patients: HEMISTIM Protocol for a Randomized Controlled Trial

Unilateral spatial neglect (USN) rehabilitation requires the development of new methods that can be easily integrated into conventional practice. The aim of the HEMISTIM protocol is to assess immediate and long-term recovery induced by an innovative association of left-side neck-muscle vibration (NMV) and anodal transcranial Direct Current Stimulation (tDCS) on the ipsilesional posterior parietal cortex during occupational therapy sessions in patients with left USN. Participants will be randomly assigned to four groups: control, Left-NMV, Left-NMV + sham-tDCS or Left-NMV + anodal-tDCS. NMV and tDCS will be applied during the first 15 min of occupational therapy sessions, three days a week for three weeks. USN will be assessed at baseline, just at the end of the first experimental session, after the first and third weeks of the protocol and three weeks after its ending. Our primary outcome will be the evolution of the functional Catherine Bergego Scale score. Secondary outcome measures include five tests that investigate different neuropsychological aspects of USN. Left NMV, by activating multisensory integration neuronal networks, might enhance effects obtained by conventional therapy since post-effects were shown when it was combined with upper limb movements. We expect to reinforce lasting intermodal recalibration through LTP-like plasticity induced by anodal tDCS.

Modulation of the executive control network by anodal tDCS over the left dorsolateral prefrontal cortex improves task shielding in dual tasking

Task shielding is an important executive control demand in dual-task performance enabling the segregation of stimulus–response translation processes in each task to minimize between-task interference. Although neuroimaging studies have shown activity in left dorsolateral prefrontal cortex (dlPFC) during various multitasking performances, the specific role of dlPFC in task shielding, and whether non-invasive brain stimulation (NIBS) may facilitate task shielding remains unclear. We therefore applied a single-blind, crossover sham-controlled design in which 34 participants performed a dual-task experiment with either anodal transcranial direct current stimulation (atDCS, 1 mA, 20 min) or sham tDCS (1 mA, 30 s) over left dlPFC. Task shielding was assessed by the backward-crosstalk effect, indicating the extent of between-task interference in dual tasks. Between-task interference was largest at high temporal overlap between tasks, i.e., at short stimulus onset asynchrony (SOA). Most importantly, in these conditions of highest multitasking demands, atDCS compared to sham stimulation significantly reduced between-task interference in error rates. These findings extend previous neuroimaging evidence and support modulation of successful task shielding through a conventional tDCS setup with anodal electrode over the left dlPFC. Moreover, our results demonstrate that NIBS can improve shielding of the prioritized task processing, especially in conditions of highest vulnerability to between-task interference.

Neuroticism modulates the qualitative effects of inferior parietal tDCS on negatively-valenced memories

For individuals with increased levels of neuroticism, experiencing criticism or receiving negative feedback has been associated with worse psychological and cognitive outcomes. Transcranial direct current stimulation (tDCS) can change cognitive processes in clinical populations. We bilaterally stimulated the posterior inferior parietal lobule (pIPL), a critical superficial node of the default model network. We investigated how baseline neuroticism modulates the impact of bilateral tDCS to pIPL on qualitative measures of memory after hearing criticism, hypothesizing that cathodal stimulation of the IPL would offer qualitative memory improvements for individuals with higher levels of neuroticism. Ninety individuals from the community were randomly assigned to receive anodal, cathodal, or sham stimulation while they were exposed to critical comments before and after stimulation. Participants then recalled the critical comments, and their linguistic responses were analyzed using Pennebaker's Linguistic Inquiry and Word Count software, a quantitative analysis software for linguistic data. Results showed that for individuals receiving cathodal tDCS, higher neuroticism scores corresponded with greater proportions of non-personal language (i.e., words such as “us,” “they,” or “other” instead of “I” or “me”) when recalling negative feedback. For individuals with higher neuroticism, cathodal tDCS stimulation, rather than anodal or sham, of the pIPL prompted increased emotional distancing and perspective taking strategies when recalling criticism. These results further highlight the state-dependent nature of tDCS effects and the role of the IPL in interpersonal processing – a clinically meaningful outcome that current tDCS studies solely examining quantitative measures of memory (e.g., task-based accuracy or speed) do not reveal.

Effects of left anodal transcranial direct current stimulation on hypothalamic–pituitary–adrenal axis activity in depression: a randomized controlled pilot trial

The main objective of this study was to evaluate the effect of left anodal transcranial direct current stimulation (tDCS) on hypothalamic–pituitary–adrenal axis (HPAA) activity in individuals with depression. We conducted a 3-week, randomized, triple-blind pilot trial with 47 participants (dropout rate: 14.89%) randomly assigned to either the tDCS or control group (sham stimulation). Salivary cortisol was used as an HPAA activity marker since cortisol is the effector hormone of the HPAA. The primary outcome was the effect of tDCS on the diurnal cortisol pattern (DCP and area under the curve with respect to ground -AUCg-). Secondary outcomes included tDCS effects on cortisol awakening response (CAR) and cortisol decline (CD), as well as the variation of cortisol concentrations between the initiation of tDCS and 2 weeks later. Intention-to-treat and per-protocol analyses were conducted. Our primary outcome showed an absent effect of tDCS on DCP and AUCg. Additionally, tDCS had an absent effect on CAR, CD, and cortisol concentration variation before-after stimulation. Our pilot study suggests that anodal tDCS showed an absent effect on HPAA activity in individuals with depression. More studies are needed to confirm these findings.

Transcranial electrical stimulation technique for induction of unilateral motor evoked potentials

ObjectiveTranscranial electrical stimulation motor evoked potentials (TES-MEP) are widely used to monitor motor function; however, broad current spread and induced body movement are limitations of this technique. We herein report a localized stimulation technique for TES-MEP that induces unilateral MEP responses. MethodsThe stimulation of C1(+)-C4(-) or C2(+)–C3(-) was performed to induce right- or left-sided muscle contraction, respectively, in 70 patients. Electromyography was recorded by placing electrodes on the bilateral abductor pollicis brevis (APB) and abductor hallucis (AH) muscles. Stimulation conditions were regulated in the range to induce unilateral muscle contractions contralateral to the anodal stimulation. The thresholds and amplitudes of TES-MEP were retrospectively analyzed. ResultsThe thresholds of APB were lower than those of AH in 47 patients, AH thresholds were lower than those of APB in 6 patients, and both APB and AH started to respond at the same intensity in 15 patients. This technical stimulation induced contralateral limb contractions with a suprathreshold stimulation of 129.4 ± 35.6 mA (mean ± standard deviation) in 68 patients (97%). Amplitudes in the suprathreshold stimulation of APB and AH responses were 727.5 ± 695.7 and 403.3 ± 325.7 μV, respectively. ConclusionsThe C1(+)–C4/C2(+)–C3(-) stimulation in TES-MEP enables a localized stimulation to induce unilateral MEP responses. SignificanceOur stimulation technique enables the stable and safe monitoring of unilateral limbs, and contributes to the reliable monitoring of motor function in neurosurgery.

Anodal tDCS over the left DLPFC but not M1 increases muscle activity and improves psychophysiological responses, cognitive function, and endurance performance in normobaric hypoxia: a randomized controlled trial

BackgroundTranscranial direct current stimulation (tDCS) has been shown to have positive effects on exercise performance and cognitive function in the normal ambient condition. Hypoxia is deemed a stressful situation with detrimental effects on physiological, psychological, cognitive, and perceptual responses of the body. Nevertheless, no study has evaluated the efficacy of tDCS for counteracting the negative effects of hypoxic conditions on exercise performance and cognition so far. Hence, in the present study, we investigated the effects of anodal tDCS on endurance performance, cognitive function, and perceptual responses in hypoxia.Participants and methodsFourteen endurance-trained males participated in five experimental sessions. After familiarization and measuring peak power output in hypoxia, in the first and second sessions, through the 3rd to 5th sessions, participants performed a cycling endurance task until exhaustion after 30 min hypoxic exposure at resting position followed by 20 min of anodal stimulation of the motor cortex (M1), left dorsolateral prefrontal cortex (DLPFC), or sham-tDCS. Color-word Stroop test and choice reaction time were measured at baseline and after exhaustion. Time to exhaustion, heart rate, saturated O2, EMG amplitude of the vastus lateralis, vastus medialis, and rectus femoris muscles, RPE, affective response, and felt arousal were also measured during the task under hypoxia.ResultsThe results showed a longer time to exhaustion (+ 30.96%, p=0.036), lower RPE (− 10.23%, p = 0.045) and higher EMG amplitude of the vastus medialis muscle (+ 37.24%, p=0.003), affective response (+ 260%, p=0.035) and felt arousal (+ 28.9%, p=0.029) in the DLPFC tDCS compared to sham. The choice reaction time was shorter in DLPFC tDCS compared to sham (− 17.55%, p=0.029), and no differences were seen in the color-word Stroop test among the conditions under hypoxia. M1 tDCS resulted in no significant effect for any outcome measure.ConclusionsWe concluded that, as a novel finding, anodal stimulation of the left DLPFC might provide an ergogenic aid for endurance performance and cognitive function under the hypoxic condition probably via increasing neural drive to the working muscles, lowering RPE, and increasing perceptual responses.

889 Significance of Cortico-Bulbar Motor Evoked Potential (CoMEP) Monitoring in Vestibular Schwannoma Surgery for Prediction of Postoperative Facial Nerve Palsy

INTRODUCTION: Direct facial nerve stimulation during vestibular schwannoma surgery (VSS) allows preservation of the nerve in its continuity. However, prognostication of post- operative nerve function remains challinging. METHODS: In total, 51 patients (median age 52yrs; 19-84) with unilateral VS (median size 20mm;10-50) were included. Intraoperative neuromonitoring consisted of auditory evoked potentials (AEPs), direct facial nerve stimulation and CoMEPs. An anodal stimulation via subdermal corkscrew electrodes on position C3 or C4 and a cathode near Cz with a train of 6 pulses, each with a duration ono 500us, at a frequency of 5000 Hz and an interstimulus-interval of 2 ms was used. RESULTS: Complete resection was achieved in &gt;90% of patients. Preoperative hearing was preserved in 78% (40/51) patients and postoperative serviceable hearing was preserved in 35% (18/49) patients and was closely related to preserved wave V of the AEPs. Additionally, MEPs were successfully monitored in every patient for the entire duration of the surgery. In 16% of the patients, more than 50% reduction of MEP baseline amplitude was recorded, correlating directly with moderate to severe postoperative facial palsy (House Brackman 3-5). No facial palsy without MEP amplitude reduction was observed. During 6 months FU, recovery of 1-2 HB Grades was observed in all cases. All patients with intraoperative MEP amplitude reduction had significant larger VS than patients without MEP amplitude reduction (27 vs 22 mm, p = 0.02) CONCLUSIONS: In addition to direct facial nerve stimulation, intraoperative CoMEP monitoring during VSS seems to be of high significance and value for intraoperative facial nerve preservation and prognosis estimation of postoperative short- and long-term facial palsy.

Vigilance decrement and mind-wandering in sustained attention tasks: Two sides of the same coin?

Decrements in performance and the propensity for increased mind-wandering (i.e., task-unrelated thoughts) across time-on-task are two pervasive phenomena observed when people perform vigilance tasks. In the present study, we asked whether processes that lead to vigilance decrement and processes that foster the propensity for mind-wandering (MW) can be dissociated or whether they share a common mechanism. In one experiment, we introduced two critical manipulations: increasing task demands and applying anodal high-definition transcranial direct current stimulation (HD-tDCS) to the left dorsolateral prefrontal cortex. Seventy-eight participants were randomly assigned to one of four groups resulting from the factorial combination of task demand (low, high) and stimulation (anodal, sham). Participants completed the sustained attention to response task (SART), which included thought probes on intentional and unintentional MW. In addition, we investigated the crucial role of alpha oscillations in a novel approach. By assessing pre-post resting EEG, we explored whether participants' variability in baseline alpha power predicted performance in MW and vigilance decrement related to tDCS or task demands, respectively, and whether such variability was a stable characteristic of participants. Our results showed a double dissociation, such that task demands exclusively affected vigilance decrement, while anodal tDCS exclusively affected the rate of MW. Furthermore, the slope of the vigilance decrement function and MW rate (overall, intentional and unintentional) did not correlate. Critically, resting state alpha-band activity predicted tDCS-related gains in unintentional MW alone, but not in vigilance decrement, and remained stable after participants completed the task. These results show that when a sustained attention task involving executive vigilance, such as the SART, is designed to elicit both vigilance decrement effects and MW, the processes leading to vigilance decrement should be differentiated from those responsible for MW, a claim that is supported by the double dissociation observed here and the lack of correlation between the measures chosen to assess both phenomena. Furthermore, the results provide the first evidence of how individual differences in alpha power at baseline may be of crucial importance in predicting the effects of tDCS on MW propensity.

Transcranial direct current stimulation enhances motor learning in Parkinson's disease: a randomized controlled trial.

Writing training has shown clinical benefits in Parkinson's disease (PD), albeit with limited retention and insufficient transfer effects. It is still unknown whether anodal transcranial direct current stimulation (atDCS) can boost consolidation in PD and how this interacts with medication. To investigate the effects of training + atDCS versus training + sham stimulation on consolidation of writing skills when ON and OFF medication. Second, to examine the intervention effects on cortical excitability. In this randomized sham-controlled double-blind study, patients underwent writing training (one session) with atDCS (N = 20) or sham (N = 19) over the primary motor cortex. Training was aimed at optimizing amplitude and assessed during online practice, pre- and post-training, after 24-h retention and after continued learning (second session) when ON and OFF medication (interspersed by 2months). The primary outcome was writing amplitude at retention. Cortical excitability and inhibition were assessed pre- and post-training. Training + atDCS but not training + sham improved writing amplitudes at retention in the ON state (p = 0.017, g = 0.75). Transfer to other writing tasks was enhanced by atDCS in both medication states (g between 0.72 and 0.87). Also, training + atDCS improved continued learning. However, no online effects were found during practice and when writing with a dual task. A post-training increase in cortical inhibition was found in the training + atDCS group (p = 0.039) but not in the sham group, irrespective of medication. We showed that applying atDCS during writing training boosted most but not all consolidation outcomes in PD. We speculate that atDCS together with medication modulates motor learning consolidation via inhibitory processes ( https://osf.io/gk5q8/ , 2018-07-17).

Anodal transcranial direct current stimulation enhances ankle force control and modulates the beta-band activity of the sensorimotor cortex.

This study aimed to investigate the cortical responses to the ankle force control and the mechanism underlying changes in ankle force control task induced by transcranial direct current stimulation (tDCS). Sixteen young adults were recruited, and they completed the electroencephalogram (EEG) assessment and high-definition tDCS (HD-tDCS) sessions. Root mean square (RMS) error was used to evaluate ankle force control task performance. Spectral power analysis was conducted to extract the average power spectral density (PSD) in the alpha (8-13Hz) and beta (13-30Hz) bands for resting state and tasking (i.e. task-PSD). The ankle force control task induced significant decreases in alpha and beta PSDs in the central, left, and right primary sensorimotor cortex (SM1) and beta PSD in the central frontal as compared with the resting state. HD-tDCS significantly decreased the RMS and beta task-PSD in the central frontal and SM1. A significant association between the percent change of RMS and the percent change of beta task-PSD in the central SM1 after HD-tDCS was observed. In conclusion, ankle force control task activated a distributed cortical network mainly including the SM1. HD-tDCS applied over SM1 could enhance ankle force control and modulate the beta-band activity of the sensorimotor cortex.

Comparison of Two Electrode Placement Methods in Transcranial Direct Current Stimulation for Parkinson's Disease

Purpose: Therapeutic electrical stimulation of deep brain structures, such as the subthalamic nucleus and the Globus Pallidus (GP), is widely accepted as a treatment tool for patients with Parkinson's Disease (PD). Electrical stimulation of the cerebral cortex with electrodes or transcranial stimulation can increase motor function among PD patients. The present study aimed to evaluate the effects of non-invasive cortical stimulation with simulation of transcranial Direct Current Stimulation (tDCS) technique on parts of the basal ganglia among PD patients.&#x0D; Materials and Methods: tDCS was simulated using two different electrode placement methods (anodal stimulation of the primary motor cortex (M1) and anodal stimulation of the Dorsolateral Prefrontal Cortex (DLPFC)) and We evaluated the excitation procedure in the target area based on the excitation current distribution in GP and Subthalamic Nucleus according to the patient's condition in both electrode methods. All simulations were performed using head Magnetic Resonance Imaging (MRI) images of four people with PD. Also, according to the excitation current distribution obtained from the previous step, we studied how the excitation current distributed in the target areas is affected by using a model of the basal ganglia so that based on the membrane potential of each excitation in these areas, in all four patients, we compare both electrode-installation methods in a functional way. The effectiveness of brain stimulation was also studied using a basal ganglia model. Considering the membrane potential of GP and Subthalamic Nucleus regions, the effectiveness of each electrode placement method was evaluated in the Basal Ganglia (BG) model.&#x0D; Results: According to the results, direct current stimulation was propagated through electrodes placed on the scalp throughout the model. Also, anodal stimulation of the M1 had a better stimulation of GP and subthalamic nucleus than anodal stimulation of the DLPFC.&#x0D; Conclusion: Although, the procedures for performing tDCS and invasive brain stimulation in PD are different, the results show that this treatment can be appropriate and improve motor function in patients with PD.