Modulating perceptual learning: Anodal transcranial direct current stimulation (tDCS) reduces the face inversion effect (FIE), while cathodal tDCS restores it to baseline.

The aim of this study was to evaluate the effect of anodal transcranial direct current stimulation over the primary somatosensory cortex on the recovery of somatosensation, motor function, and the activities of daily living in patients with subacute stroke. This study was a prospective, randomized sham controlled, double-blinded study. Patients with subacute stroke having somatosensory deficits (N = 24) were enrolled and assigned randomly to the anodal and sham stimulation groups. Patients received 10 consecutive anodal or sham transcranial direct current stimulations over the primary somatosensory cortex on the side of the stroke lesion. Before and after each stimulation session, Nottingham sensory assessments, Semmes Weinstein monofilaments examination, and manual function tests were performed, and modified Brunnstrom classification, modified Barthel index, and functional ambulation categories were assessed. Although there was no clear significant difference between the two groups, when the changes from baseline to posttreatment evaluation were compared between the groups, a partially significant improvement was observed in the anodal stimulation group compared with the sham stimulation group. Interestingly, the tactile sensation of the unaffected side also improved. Moreover, the greater improvement in activities of daily living function was observed in the anodal stimulation group too. Anodal transcranial direct current stimulation over the primary somatosensory cortex may be a useful adjuvant therapy for the recovery of somatosensation and activities of daily living function in patients with sensory deficits after stroke.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.

Transcranial direct current stimulation (tDCS) of the human cerebral cortex modulates cortical excitability noninvasively in a polarity-specific manner: anodal tDCS leads to lasting facilitation and cathodal tDCS to inhibition of motor cortex excitability. To further elucidate the underlying physiological mechanisms, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation of the primary motor cortex before and after a 5-min period of anodal or cathodal tDCS in eight conscious patients who had electrodes implanted in the cervical epidural space for the control of pain. The effects of anodal tDCS were evaluated in six subjects and the effects of cathodal tDCS in five subjects. Three subjects were studied with both polarities. Anodal tDCS increased the excitability of cortical circuits generating I waves in the corticospinal system, including the earliest wave (I1 wave), whereas cathodal tDCS suppressed later I waves. The motor evoked potential (MEP) amplitude changes immediately following tDCS periods were in agreement with the effects produced on intracortical circuitry. The results deliver additional evidence that tDCS changes the excitability of cortical neurons.

Methamphetamine use disorder (MUD) is associated with significant impairments in impulsivity control, contributing to relapse and poor treatment outcomes. Transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) may be helpful in modulating these symptoms. This study aimed at [1] investigating the differential effects of anodal and cathodal tDCS on craving, affective impulsivity, and motor impulsivity; and [2] exploring the correlations between changes in affective impulsivity & drug craving, and alterations in resting-state electroencephalography (Rs-EEG) microstate parameters following tDCS interventions. A randomized, parallel, double-blind experimental study. Two drug rehabilitation centers in China, from June 2022 to June 2023. One hundred male participants (ages 33.7 ± 6.26 years) during rehabilitation for MUD. Participants were randomly assigned to anodal (n = 33), cathodal (n = 31), or sham (n = 36) tDCS conditions. tDCS was delivered at 2mA (anodal and cathodal) or 0mA (sham) for 20 minutes, twice daily for ten consecutive days. The central electrode was placed on the left dorsolateral prefrontal cortex. Primary and secondary outcomes were assessed at four time points: baseline (before intervention), post-intervention 1 (after two sessions), post-intervention 2 (after 20 sessions, primary time-point), and one-month follow-up (post-intervention 3). Primary outcomes were affective impulsivity and motor impulsivity. Secondary outcomes included drug craving, Rs-EEG microstates, and adverse effects. Anodal tDCS statistically significantly improved affective impulsivity control after 20 sessions (estimate = -36.23, 95% confidence interval [CI] [-59.72, -12.73], p < 0.01) but not motor impulsivity control. Both anodal and cathodal tDCS statistically significantly reduced drug craving after 20 sessions (anodal: estimate = 3.36, 95% CI [1.15, 5.57], p < 0.01; cathodal: estimate = 2.62, 95% CI [0.34, 4.9], p = 0.02). Changes in affective impulsivity were statistically significantly correlated with alterations in Rs-EEG microstate parameters, such as microstate B coverage (r = 0.29, p. < 0.01, n = 100); however, there is a lack of clear evidence for correlations between changes in craving and microstate parameters. Among methamphetamine users in rehabilitation, anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex appears to improve affective impulsivity control, but not motor impulsivity control, and both anodal and cathodal tDCS reduce drug craving.

Lewis, A, Rattray, B, and Flood, A. Does cathodal preconditioning enhance the effects of subsequent anodal transcranial direct current stimulation on corticospinal excitability and grip strength? J Strength Cond Res 39(1): e1-e12, 2025-Inconsistent effects of transcranial direct current stimulation (tDCS) on corticospinal excitability (CSE) and exercise performance are commonly reported. Cathodal preconditioning, involving cathodal tDCS delivered before anodal tDCS over the same region, may enhance changes in CSE and exercise beyond that resulting from anodal tDCS alone. This study aimed to investigate whether the effects of anodal tDCS on CSE and isometric grip strength can be enhanced by cathodal preconditioning. Thirty-five healthy subjects aged 19-37 years completed a familiarization session followed by 4 stimulation conditions presented in a randomized cross-over design across 4 separate sessions. tDCS doses were applied at 2 mA over the primary motor cortex for 10 minutes. Corticospinal excitability was assessed using 120% of resting motor threshold and an input/output curve of motor evoked potentials of the first dorsal interosseous. Grip strength was evaluated as time to exhaustion (TTE) in a sustained isometric contraction. Relative to conventional sham stimulation, TTE was significantly increased by 15% after conventional anodal tDCS. Corticospinal excitability increased in response to tDCS, but this effect did not differ across conditions. Cathodal preconditioning before anodal stimulation did not increase CSE or grip strength beyond that seen in the other stimulation conditions. Our findings did not reveal any significant impact of stimulation type on CSE. Notably, anodal tDCS led to a significant improvement in grip strength endurance. However, cathodal preconditioning did not seem to increase the effect of subsequent anodal stimulation on CSE nor grip strength.

P 234. Transcranial direct current stimulation and Alzheimer’s disease

The role of transcranial direct current stimulation (tDCS) as an ergogenic aid is receiving attention from scientists to optimize sport performance. Most studies have examined the effects of tDCS on endurance performance during continuous tasks, while the effect of tDCS on high-intensity intermittent tasks has been less investigated. Therefore, this study aimed to explore the acute effects of tDCS on sprint performance and ratings of perceived exertion (RPE) during a repeated sprint ability (RSA) task. Twenty-five healthy males (age: 22.0 ± 2.5 years) participated in a randomized crossover study consisting of three experimental sessions (anodal, cathodal or sham tDCS) separated by 1 week. Each session consisted of (I) tDCS protocol (15 min at 2 mA applied over the dorsolateral prefrontal cortex [DLPFC]), (II) warm-up and (III) RSA task (ten 30-m running sprints separated by 30 s). Total time and RPE values were recorded for each sprint. The two-way ANOVA applied on sprint time did not reveal a significant main effect of tDCS condition (p = .200) neither a significant tDCS condition × number of sprint interaction (p = .716). Similarly, no significant differences were observed for the fatigue index (p = .449), RSAmean (p = .200) or RPE after each sprint (p range = .116–.890). The magnitude of the differences between the tDCS conditions ranged from negligible to small (effect sizes ≤ 0.33). These results suggest that the application of tDCS over the DLPFC is not effective to increase sprint performance or reduce RPE during a RSA task. HIGHLIGHTS Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that could modulate neuromuscular performance. This study aimed to explore the short-term effects of tDCS on sprint performance and ratings of perceived exertion (RPE) during a repeated sprint ability (RSA) task. The application of either ANODAL or CATHODAL tDCS over the DLPFC for 15 minutes did not affect the sprint time of single repeated sprints or the overall metrics of RSA performance (RSAmean and fatigue index). The application of either ANODAL or CATHODAL tDCS over the DLPFC for 15 minutes did not affect the ratings of perceived exertion measured during the repeated sprints task.

In the 3 experiments reported here we show that a specific neurostimulation method, whose influence can be understood in terms of a well-known theory of stimulus representation, is able to affect face recognition skills by impairing participants' performance for upright faces. We used the transcranial Direct Current Stimulation (tDCS) procedure we have recently developed that allows perceptual learning, as indexed by the face inversion effect, to be modulated. We extended this tDCS procedure to another phenomenon, the composite face effect, which constitutes better recognition of the top half of an upright face when conjoined with a congruent (in terms of the response required) rather than incongruent bottom half. All three experiments used the Face-Matching task traditionally used to study this phenomenon. Experiment 1a (n = 48) showed that anodal tDCS (using a double-blind between-subjects design) delivered at Fp3 (10 mins at 1.5 mA) affected overall performance for upright faces compared with sham but had no effect on the composite face effect itself. Experiment 1b (n = 48) replicated our usual tDCS-induced effects on the face inversion effect but this time using a Face-Matching task instead of the old/new recognition task previously used to obtain the effect. Experiment 2 (n = 72) replicated the findings from Experiment 1a, and, using an active control group, showed that the Fp3 anodal tDCS effects on performance to upright faces are not obtained when a different brain area is targeted. We interpret our results in the light of previous literature on the tDCS effects on perceptual learning and face recognition and suggest that different mechanisms are involved in the face inversion effect and the composite face effect. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Event Abstract Back to Event Transcranial direct current stimulation at training can improve subsequent consolidation of a visual perceptual skill Katia Boumghar1*, Katja Laske1, Matthias Mölle1, Jan Born1 and Lisa Marshall1 1 Department of Neuroendocrinology, University of Lübeck, Germany In humans, transcranial direct current stimulation (tDCS) is used to induce cortical polarization and excitability shifts which can result in acute as well as longer lasting effects. Here we investigated at the behavioral level the effects of cathodal and anodal tDCS applied during learning on the overnight improvement in a visual texture discrimination task (VDT). The VDT requires learning of a procedural skill in which robust improvement is typically obtained only after post-training retention periods containing sleep. In the VDT learning and retest are spaced 24h apart. On each trial, subjects fix a central cross and activate the beginning of each trial consisting of the target and mask for which the time interval of separation (stimulus-to-mask-onset, SOA) decreases over time. Subjects are to judge the orientation of target-lines (horizontal or vertical). The subjects of both experimental groups receive on one of two weeks either anodal (cathodal) or sham stimulation over V1. Cathodal tDCS applied during learning led to a significant decrease in the discrimination threshold measured at retesting the following day, as compared to a sham stimulation control condition. No acute effect of stimulation during training was found, nor did anodal tDCS affect performance. We propose that the effect of cathodal tDCS in the VDT reflects the ability of endogenous polarization fields as induced by simple neuronal processing steps or attentional shifts to impact latent improvement in performance. Differences in the early component of the visual potential dependent upon learning on the VDT task have been reported (Pourtois et al., 2008). In order to assess possible underlying mechanisms the visual evoked potentials (VEP) are currently being recorded. Funding: Supported by BMBF, DFG. Keywords: Learning, tDCS Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Neural Bases of Memory and Learning Citation: Boumghar K, Laske K, Mölle M, Born J and Marshall L (2011). Transcranial direct current stimulation at training can improve subsequent consolidation of a visual perceptual skill. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00408 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Katia Boumghar, Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany, boumghar@kfg.uni-luebeck.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Katia Boumghar Katja Laske Matthias Mölle Jan Born Lisa Marshall Google Katia Boumghar Katja Laske Matthias Mölle Jan Born Lisa Marshall Google Scholar Katia Boumghar Katja Laske Matthias Mölle Jan Born Lisa Marshall PubMed Katia Boumghar Katja Laske Matthias Mölle Jan Born Lisa Marshall Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

P 99. Effects of transcranial direct-current stimulation on diaphragm corticospinal pathway excitability

The contribution of poor finger force control to age-related decline in manual dexterity is above and beyond ubiquitous behavioral slowing. Altered control of the finger forces can impart unwanted torque on the object affecting its orientation, thus impairing manual performance. Anodal transcranial direct current stimulation (tDCS) over primary motor cortex (M1) has been shown to improve the performance speed on manual tasks in older adults. However, the effects of anodal tDCS over M1 on the finger force control during object manipulation in older adults remain to be fully explored. Here we determined the effects of anodal tDCS over M1 on the control of grip force in older adults while they manipulated an object with an uncertain mechanical property. Eight healthy older adults were instructed to grip and lift an object whose contact surfaces were unexpectedly made more or less slippery across trials using acetate and sandpaper surfaces, respectively. Subjects performed this task before and after receiving anodal or sham tDCS over M1 on two separate sessions using a cross-over design. We found that older adults used significantly lower grip force following anodal tDCS compared to sham tDCS. Friction measured at the finger-object interface remained invariant after anodal and sham tDCS. These findings suggest that anodal tDCS over M1 improved the control of grip force during object manipulation in healthy older adults. Although the cortical networks for representing objects and manipulative actions are complex, the reduction in grip force following anodal tDCS over M1 might be due to a cortical excitation yielding improved processing of object-specific sensory information and its integration with the motor commands for production of manipulative forces. Our findings indicate that tDCS has a potential to improve the control of finger force during dexterous manipulation in older adults.

SummaryElectrophysiological studies in humans and animals suggest that noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting [1], polarity-dependent [2] changes in neocortical excitability. Application of tDCS can have significant and selective behavioral consequences that are associated with the cortical location of the stimulation electrodes and the task engaged during stimulation [3–8]. However, the mechanism by which tDCS affects human behavior is unclear. Recently, functional magnetic resonance imaging (fMRI) has been used to determine the spatial topography of tDCS effects [9–13], but no behavioral data were collected during stimulation. The present study is unique in this regard, in that both neural and behavioral responses were recorded using a novel combination of left frontal anodal tDCS during an overt picture-naming fMRI study. We found that tDCS had significant behavioral and regionally specific neural facilitation effects. Furthermore, faster naming responses correlated with decreased blood oxygen level-dependent (BOLD) signal in Broca's area. Our data support the importance of Broca's area within the normal naming network and as such indicate that Broca's area may be a suitable candidate site for tDCS in neurorehabilitation of anomic patients, whose brain damage spares this region.

Polarity-specific effects of motor transcranial direct current stimulation on fMRI resting state networks

Effects of simultaneous bilateral tDCS of the human motor cortex

Transcranial direct current stimulation (tDCS) is increasingly used in both research and therapeutic settings, but its precise mechanisms remain largely unknown. At a neuronal level, tDCS modulates cortical excitability by shifting the resting membrane potential in a polarity-dependent way: anodal stimulation increases the spontaneous firing rate, while cathodal decreases it. However, the neurophysiological underpinnings of anodal/cathodal tDCS seem to be different, as well as their behavioral effect, in particular when high order areas are involved, compared to when motor or sensory brain areas are targeted. Previously, we investigated the effect of anodal tDCS on cortical excitability, by means of a combination of Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG). Results showed a diffuse rise of cortical excitability in a bilateral fronto-parietal network. In the present study, we tested, with the same paradigm, the effect of cathodal tDCS. Single pulse TMS was delivered over the left posterior parietal cortex (PPC), before, during, and after 10 min of cathodal or sham tDCS over the right PPC, while recording HD-EEG. Indexes of global and local cortical excitability were obtained both at sensors and cortical sources level. At sensors, global and local mean field power (GMFP and LMFP) were computed for three temporal windows (0–50, 50–100, and 100–150 ms), on all channels (GMFP), and in four different clusters of electrodes (LMFP, left and right, in frontal and parietal regions). After source reconstruction, Significant Current Density was computed at the global level, and for four Broadmann's areas (left/right BA 6 and 7). Both sensors and cortical sources results converge in showing no differences during and after cathodal tDCS compared to pre-stimulation sessions, both at global and local level. The same holds for sham tDCS. These data highlight an asymmetric impact of anodal and cathodal stimulation on cortical excitability, with a diffuse effect of anodal and no effect of cathodal tDCS over the parietal cortex. These results are consistent with the current literature: while anodal-excitatory and cathodal-inhibitory effects are well-established in the sensory and motor domains, both at physiological and behavioral levels, results for cathodal stimulation are more controversial for modulation of exitability of higher order areas.