P015 The effects of cathodal transcranial direct current stimulation in patienst with focal epilepsy (a pilot study)‘

Repeated transcranial magnetic stimulation (rTMS) is a well-known clinical neuromodulation technique, but transcranial direct-current stimulation (tDCS) is rapidly growing interest for neurorehabilitation applications. Both methods (contralesional hemisphere inhibitory low-frequency: LF-rTMS or lesional hemisphere excitatory anodal: a-tDCS) have been employed to modify the interhemispheric imbalance following stroke. The aim of this pilot study was to compare aHD-tDCS (anodal high-definition tDCS) of the left M1 (2 mA, 20 min) and LF-rTMS of the right M1 (1 Hz, 20 min) to enhance excitability and reduce inhibition of the left primary motor cortex (M1) in five healthy subjects. Single-pulse TMS was used to elicit resting and active (low level muscle contraction, 5% of maximal electromyographic signal) motor-evoked potentials (MEPs) and cortical silent periods (CSPs) from the right and left extensor carpi radialis muscles at Baseline, immediately and 20 min (Post-Stim-20) after the end of each stimulation protocol. LF-rTMS or aHD-tDCS significantly increased right M1 resting and active MEP amplitude at Post-Stim-20 without any CSP modulation and with no difference between methods. In conclusion, this pilot study reported unexpected M1 excitability changes, which most likely stems from variability, which is a major concern in the field to consider.

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Auditory P300 as a Neurophysiological Correlate of Symptomatic Improvement by Transcranial Direct Current Stimulation in Patients With Schizophrenia: A Pilot Study

Clinical EEG and Neuroscience ◽

10.1177/1550059418815228 ◽

2018 ◽

Vol 51 (4) ◽

pp. 252-258

Author(s):

Minah Kim ◽

Tak Hyung Lee ◽

Wu Jeong Hwang ◽

Tae Young Lee ◽

Jun Soo Kwon

Keyword(s):

Pilot Study ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Negative Symptoms ◽

Symptomatic Improvement ◽

P300 Amplitude ◽

Direct Current Stimulation ◽

Auditory P300 ◽

Related Potentials ◽

Positive And Negative Symptoms

Background. The reduced amplitude, prolonged latency, and increased intertrial variability of auditory P300 have been consistently reported in relation to the symptomatic severity of schizophrenia. This study investigated whether auditory P300 event-related potentials can be used as an objective indicator of symptomatic improvement by transcranial direct current stimulation (tDCS) in patients with schizophrenia. Methods. Ten patients with schizophrenia received 20 minutes of 2-mA tDCS twice a day for 5 consecutive weekdays. The anode was placed over the left dorsolateral prefrontal cortex, and the cathode was placed over the left temporo-parietal cortex. The Positive and Negative Syndrome Scale (PANSS) and the auditory P300 were measured for each participant at baseline and after the completion of the tDCS applications. Results. The participants showed significant improvement in the positive and negative symptoms as indexed by change in the PANSS scores by the tDCS. The P300 amplitude, latency, and intertrial variability did not statistically significantly differ after the tDCS application. However, a significant association was observed between the reduced P300 intertrial variability and improvement in the positive symptoms by tDCS. In addition, the changes in both the P300 latency and intertrial variability were significantly correlated with reduced negative symptoms after the tDCS application. Conclusions. Although this pilot study is limited by the small sample size and lack of a sham control, the results suggest that auditory P300 may be a putative marker reflecting the effect of tDCS on the positive and negative symptoms of schizophrenia.

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Functional Network Alterations as Markers for Predicting the Treatment Outcome of Cathodal Transcranial Direct Current Stimulation in Focal Epilepsy

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.637071 ◽

2021 ◽

Vol 15 ◽

Author(s):

Jiaxin Hao ◽

Wenyi Luo ◽

Yuhai Xie ◽

Yu Feng ◽

Wei Sun ◽

...

Keyword(s):

Treatment Outcome ◽

Prediction Model ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Path Length ◽

Focal Epilepsy ◽

Functional Network ◽

Functional Networks ◽

Direct Current Stimulation ◽

The Mean

Background and PurposeTranscranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique for focal epilepsy. Because epilepsy is a disease affecting the brain network, our study was aimed to evaluate and predict the treatment outcome of cathodal tDCS (ctDCS) by analyzing the ctDCS-induced functional network alterations.MethodsEither the active 5-day, −1.0 mA, 20-min ctDCS or sham ctDCS targeting at the most active interictal epileptiform discharge regions was applied to 27 subjects suffering from focal epilepsy. The functional networks before and after ctDCS were compared employing graph theoretical analysis based on the functional magnetic resonance imaging (fMRI) data. A support vector machine (SVM) prediction model was built to predict the treatment outcome of ctDCS using the graph theoretical measures as markers.ResultsOur results revealed that the mean clustering coefficient and the global efficiency decreased significantly, as well as the characteristic path length and the mean shortest path length at the stimulation sites in the fMRI functional networks increased significantly after ctDCS only for the patients with response to the active ctDCS (at least 20% reduction rate of seizure frequency). Our prediction model achieved the mean prediction accuracy of 68.3% (mean sensitivity: 70.0%; mean specificity: 67.5%) after the nested cross validation. The mean area under the receiver operating curve was 0.75, which showed good prediction performance.ConclusionThe study demonstrated that the response to ctDCS was related to the topological alterations in the functional networks of epilepsy patients detected by fMRI. The graph theoretical measures were promising for clinical prediction of ctDCS treatment outcome.

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