Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Transcranial Direct Current Stimulation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2003

Modulation of moving phosphene thresholds by transcranial direct current stimulation of V1 in human.

Small moving sensations, so-called moving phosphenes are perceived, when V5, a visual area important for visual motion analysis, is stimulated by transcranial magnetic stimulation (TMS). However, it is still a matter of debate if only V5 takes part in movement perception or other visual areas are also involved in this process. In this study we tested the involvement of V1 in the perception of moving phosphenes by applying transcranial direct current stimulation (tDCS) to this area. tDCS is a non-invasive stimulation technique known to modulate cortical excitability in a polarity-specific manner. Moving and stationary phosphene thresholds (PT) were measured by TMS before, immediately after and 10, 20 and 30 min after the end of 10 min cathodal and anodal tDCS in nine healthy subjects. Reduced PTs were detected immediately and 10 min after the end of anodal tDCS while cathodal stimulation resulted in an opposite effect. Our results show that the excitability shifts induced by V1 stimulation can modulate moving phosphene perception. tDCS elicits transient, but yet reversible effects, thus presenting a promising tool for neuroplasticity research.

Adult↗
PubMed2006

Modeling the current distribution during transcranial direct current stimulation.

OBJECTIVE: To investigate the spatial distribution of the magnitude and direction of the current density in the human head during transcranial direct current stimulation (tDCS). METHODS: The current density distribution was calculated using a numerical method to implement a standard spherical head model into which current was injected by means of large electrodes. The model was positioned in 'MNI space' to facilitate the interpretation of spatial coordinates. RESULTS: The magnitude and direction of the current density vector are illustrated in selected brain slices for four different electrode montages. Approximately half of the current injected during tDCS is shunted through the scalp, depending on electrode dimension and position. Using stimulating currents of 2.0 mA, the magnitude of the current density in relevant regions of the brain is of the order of 0.1 A/m2, corresponding to an electric field of 0.22 V/m. CONCLUSIONS: Calculations based on a spherical model of the head can provide useful information about the magnitude and direction of the current density vector in the brain during tDCS, taking into account the geometry and position of the electrodes. Despite the inherent limitations of the spherical head model, the calculated values are comparable to those used in the most recent in vitro studies on modulation of neuronal activity. SIGNIFICANCE: The methodology presented in this paper may be used to assess the current distribution during tDCS using new electrode montages, to help optimize montages that target a specific region of the brain or to preliminarily investigate compliance with safety guidelines.

Brain↗
PubMed2006

Transcranial direct current stimulation of the primary motor cortex affects cortical drive to human musculature as assessed by intermuscular coherence.

Intermuscular coherence analysis can be used to assess the common drive to muscles. Coherence in the beta-frequency band (15-35 Hz) is thought to arise from common cortical sources. Intermuscular coherence analysis is a potentially attractive tool for the investigation of motor cortical excitability changes because it is non-invasive and can be done relatively quickly. We carried out this study to test the hypothesis that intermuscular coherence analysis was able to detect cortical excitability changes in healthy subjects following transcranial direct current stimulation (tDCS). tDCS has been shown to increase (anodal stimulation) or decrease (cathodal stimulation) the size of the muscle potential evoked by TMS. We found that anodal tDCS caused an increase in motor evoked potential (MEP) size that was paralleled by an increase in beta-band intermuscular coherence. Similarly, the reduction in MEP size produced by cathodal tDCS was paralleled by a reduction in beta-band intermuscular coherence, while sham stimulation did not result in any change in either MEP amplitude or beta-band intermuscular coherence. The similar pattern of change observed for MEP and intermuscular coherence may indicate similar mechanisms of action, although this cannot be assumed without further investigation. These changes do suggest that at least some of the action of tDCS is on cortical networks, and that combined tDCS and intermuscular coherence analysis may be useful in the diagnosis of pathologies affecting motor cortical excitability.

Adult↗
PubMed2004

Facilitation of visuo-motor learning by transcranial direct current stimulation of the motor and extrastriate visual areas in humans.

Performance of visuo-motor tasks requires the transfer of visual data to motor performance and depends highly on visual perception and cognitive processing, mainly during the learning phase. The primary aim of this study was to determine if the human middle temporal (MT)+/V5, an extrastriate visual area that is known to mediate motion processing, and the primary motor cortex are involved in learning of visuo-motor coordination tasks. To pursue this, we increased or decreased MT+/V5, primary contralateral motor (M1) and primary visual cortex excitability by 10 min of anodal or cathodal transcranial direct current stimulation in healthy human subjects during the learning phase of a visually guided tracking task. The percentage of correct tracking movements increased significantly in the early learning phase during anodal stimulation, but only when the left V5 or M1 was stimulated. Cathodal stimulation had no significant effect. Also, stimulation of the primary visual cortex was not effective for this kind of task. Our data suggest that the areas V5 and M1 are involved in the early phase of learning of visuo-motor coordination.

Adult↗
PubMed2005

Transcranial direct current stimulation and the visual cortex.

Neuroplastic changes are defined as enduring changes in the organization of the central nervous system, such as the strength of connections, representational patterns, or neuronal properties, either morphological or functional. In recent years, new tools have emerged to induce and manipulate ongoing neuroplastic changes by external stimulation, either by modification of synchronized neuronal activity or modulation of the spontaneous firing rate. The first is performed by transcranial magnetic stimulation (TMS), the latter by direct current stimulation (tDCS). tDCS as a tool aims to induce prolonged neuronal excitability and activity alterations in the human brain via alterations of the neuronal membrane potential and results in prolonged synaptic efficacy changes. Apart from its impressive persistent excitability effects, it is a non-invasive method and can be applied painlessly. Most likely that up- or downregulation of different cortical areas by tDCS will open a new branch in the area of visual psychophysics.

Animals↗
PubMed2005

Bifrontal transcranial direct current stimulation slows reaction time in a working memory task.

BACKGROUND: Weak transcortical direct current stimulation (tDCS) applied to the cortex can shift the membrane potential of superficial neurons thereby modulating cortical excitability and activity. Here we test the possibility of modifying ongoing activity associated with working memory by tDCS. The concept of working memory applies to a system that is capable of transiently storing and manipulating information, as an integral part of the human memory system. We applied anodal and cathodal transcranial direct current (tDCS) stimulation (260 microA) bilaterally at fronto-cortical electrode sites on the scalp over 15 min repeatedly (15 sec-on/15 sec-off) as well as sham-tDCS while subjects performed a modified Sternberg task. RESULTS: Reaction time linearly increased with increasing set size. The slope of this increase was closely comparable for real and sham stimulation indicating that our real stimulation did not effect time required for memory scanning. However, reaction time was slowed during both anodal and cathodal stimulation as compared to placebo (p < 0.05) indicating that real stimulation hampered neuronal processing related to response selection and preparation. CONCLUSION: Intermittent tDCS over lateral prefrontal cortex during a working memory task impairs central nervous processing related to response selection and preparation. We conclude that this decrease in performance by our protocol of intermittent stimulation results from an interference mainly with the temporal dynamics of cortical processing as indexed by event-related sustained and oscillatory EEG activity such as theta.

Adult↗
PubMed2000

Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation.

In this paper we demonstrate in the intact human the possibility of a non-invasive modulation of motor cortex excitability by the application of weak direct current through the scalp. Excitability changes of up to 40 %, revealed by transcranial magnetic stimulation, were accomplished and lasted for several minutes after the end of current stimulation. Excitation could be achieved selectively by anodal stimulation, and inhibition by cathodal stimulation. By varying the current intensity and duration, the strength and duration of the after-effects could be controlled. The effects were probably induced by modification of membrane polarisation. Functional alterations related to post-tetanic potentiation, short-term potentiation and processes similar to postexcitatory central inhibition are the likely candidates for the excitability changes after the end of stimulation. Transcranial electrical stimulation using weak current may thus be a promising tool to modulate cerebral excitability in a non-invasive, painless, reversible, selective and focal way.

Adult↗
PubMed2003

Transcranial direct current stimulation (tDCS).

tDCS appears to be a promising tool in neuroplasticity research with some tentative perspectives in clinical neurophysiology. The next steps to be carried out encompass better histological safety data. In order to preclude the possibility of neuronal damage, extending tDCS duration should be limited until more direct safety criteria are available than those derived from Agnew and McCreery (1987) (cf. Nitsche et al, this volume). Safe stimulation protocols have to be developed which allow an extension of the duration of after-effects towards a somewhat permanent state, supposing a beneficial effect can be found in neurological diseases or in neurorehabilitation.

Animals↗
PubMed2006

Does brain stimulation after stroke have a future?

PURPOSE OF REVIEW: Transcranial methods of cortical stimulation can induce long-term changes in excitability of the cerebral cortex in humans and may be useful as therapeutic interventions in stroke rehabilitation. RECENT FINDINGS: Two approaches have been tested: (1) increasing excitability of the cortex in the stroke hemisphere and (2) suppression of the non-stroke hemisphere to reduce potential interference with function of the stroke hemisphere. The interventions have been transcranial direct current stimulation, transcranial magnetic stimulation and implanted epidural stimulation. All have been reported to give 10-20% functional improvement in small numbers of patients in single-session studies as well as in a small number of longer-term therapeutic trials. Preliminary experiments in aphasic patients using transcranial magnetic stimulation in an interference design show, however, that stimulation of the nonstroke hemisphere can in some patients reduce verbal fluency, questioning the general applicability of the second approach. SUMMARY: Cortical stimulation appears to be a safe and promising intervention for stroke patients. More studies are needed to assess its long-term benefits on substantial numbers of patients. We need to know what type of intervention is best, which patients are likely to benefit, the optimum time to intervene and the duration of any benefits.

Aphasia↗
PubMed2026

Assessing the effects of non-invasive transcranial electrical stimulation (tACS and tDCS) on electrophysiological sleep parameters - a systematic review.

Transcranial electrical stimulation (tES), including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), is considered a safe method to modulate cortical activity and endogenous brain oscillations. Given the therapeutic potential of tES across various clinical conditions and the central role of sleep in restoration and memory consolidation, numerous studies have investigated its effects on sleep and sleep-related parameters, yielding inconsistent results. This systematic review provides an up-to-date synthesis of 51 studies assessing the impact of tES on objectively measured electrophysiological sleep outcomes in both healthy individuals and clinical populations. The reviewed studies demonstrate heterogeneous effects, reflecting substantial variability in study designs. Nonetheless, consistent trends emerge, including reduced NREM1 and increases in total sleep time, NREM2, and NREM3 following tES. Moreover, slow-oscillatory tES increased slow-wave power during sleep. Here we show that tES, particularly slow-oscillatory tES, may positively influence sleep architecture and continuity by modulating endogenous brain oscillations. However, due to heterogeneous stimulation protocols, inconsistent findings, the limited number of significant effects and substantial risk of bias the current evidence remains inconclusive. Well-designed, large-scale trials targeting specific sleep outcomes are needed to clarify the therapeutic potential of tES.

Humans↗
PubMed2006

Non-invasive brain stimulation: a new strategy to improve neurorehabilitation after stroke?

BACKGROUND: Motor impairment resulting from chronic stroke can have extensive physical, psychological, financial, and social implications despite available neurorehabilitative treatments. Recent studies in animals showed that direct epidural stimulation of the primary motor cortex surrounding a small infarct in the lesioned hemisphere (M1(lesioned hemisphere)) elicits improvements in motor function. RECENT DEVELOPMENTS: In human beings, proof of principle studies from different laboratories showed that non-invasive transcranial magnetic stimulation and direct current stimulation that upregulate excitability within M1(lesioned hemisphere) or downregulate excitability in the intact hemisphere (M1(intact hemisphere)) results in improvement in motor function in patients with stroke. Possible mechanisms mediating these effects can include the correction of abnormally persistent interhemispheric inhibitory drive from M1(intact hemisphere) to M1(lesioned hemisphere) in the process of generation of voluntary movements by the paretic hand, a disorder correlated with the magnitude of impairment. In this paper we review these mechanistically oriented interventional approaches. WHAT NEXT?: These findings suggest that transcranial magnetic stimulation and transcranial direct current stimulation could develop into useful adjuvant strategies in neurorehabilitation but have to be further assessed in multicentre clinical trials.

Animals↗