scholarly journals S192. EFFECTS OF NICOTINE INTAKE ON NEUROPLASTICITY IN SMOKING AND NON-SMOKING PATIENTS WITH SCHIZOPHRENIA

2020 ◽  
Vol 46 (Supplement_1) ◽  
pp. S111-S112
Author(s):  
Benjamin Pross ◽  
Patrick Schulz ◽  
Duygu Güler ◽  
Irina Papazova ◽  
Elias Wagner ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Environmental Changes ◽  
Cortical Plasticity ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Receptor Activation ◽  
Pathophysiological Mechanism ◽  
Direct Current Stimulation ◽  
Nicotine Consumption

Abstract Background Cortical plasticity – the ability to reorganize synaptic connections and adapt to environmental changes – appears to be impaired in schizophrenia patients. Results suggest the dysfunctional plasticity to be a key pathophysiological mechanism. Different non-invasive brain stimulation (NIBS) techniques have been used to modulate and induce cortical plasticity. In healthy subjects, nicotine was shown to play an important role in plasticity induction and is capable to alter cortical excitability and plasticity, induced by NIBS techniques. Our goal was to investigate the promising effects of a nicotine receptor activation done by Varenicline and the combination with anodal transcranial direct current stimulation (a-tDCS) on neuroplastic changes in schizophrenia patients. Methods Our sample consisted out of twenty-four individuals with schizophrenia, twelve smokers and twelve non-smokers. Every participant received Varenicline and Placebo, combined with anodal transcranial direct current stimulation (a-tDCS), to induce non-focal plasticity. We inferred plasticity changes by monitoring changes in cortical excitability. This was done via motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS). The MEPs were recorded before and three hours after Varenicline/Placebo intake. Following the direct current stimulation, we monitored excitability changes for up to one hour. Results Significant effects through the mere Varenicline consumption or withdrawal effects could not be found in any group. However, we observed a numeric temporary decrease of excitability after a-tDCS in non-smokers following Varenicline intake. This decrease compared to the placebo condition was visible 20 minutes after a-tDCS but vanished over time. Smokers did not show any excitability changes after a-tDCS and the nicotinic receptor stimulation did not show any influence. Excitability changes after stimulation in contrast to the baseline measurement were not evident. Discussion Our results show that an activation of nicotinic receptors in schizophrenia patients does not induce excitability changes. The modulating effect of nicotine in plasticity induction via anodal transcranial direct current stimulation could not be confirmed for patients with schizophrenia. We could show that chronic nicotine consumption in patients with schizophrenia or nicotine withdrawal does not lead to fundamental excitability changes. Acute nicotine consumption has only small effects on cortical excitability in non-smokers.

scholarly journals The effects of transcranial direct current stimulation on corticospinal and cortico-cortical excitability and response variability: conventional versus high-definition montages

2020 ◽  
Author(s):  
Michael Pellegrini ◽  
Maryam Zoghi ◽  
Shapour Jaberzadeh
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Individual Variability ◽  
Response Variability ◽  
Pulse Interval ◽  
Direct Current Stimulation

AbstractResponse variability following transcranial direct current stimulation (tDCS) highlights need for exploring different tDCS electrode montages. This study compared corticospinal excitability (CSE), cortico-cortical excitability and intra-individual variability following conventional and HD anodal (a-tDCS) and cathodal (c-tDCS) tDCS. Fifteen healthy young males attended four sessions at least one-week apart: conventional a-tDCS, conventional c-tDCS, HD-a-tDCS, HD-c-tDCS. TDCS was administered (1mA, 10-minutes) over the primary motor cortex (M1), via 6×4cm active and 7×5cm return electrodes (conventional tDCS) and 4×1 ring-electrodes 3.5cm apart in ring formation around M1 (HD-tDCS). For CSE, twenty-five single-pulse transcranial magnetic stimulation (TMS) peak-to-peak motor evoked potentials (MEP) were recorded at baseline, 0-minutes and 30-minutes post-tDCS. For cortico-cortical excitability, twenty-five paired-pulse MEPs with 3-millisecond (ms) inter-pulse interval (IPI) and twenty-five at 10ms assessed short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) respectively. MEP standardised z-values standard deviations represented intra-individual variability. No significant differences were reported in CSE between conventional and HD a-tDCS, but significant differences between conventional and HD c-tDCS 0-minutes post-tDCS. Intra-individual variability was significantly reduced in conventional tDCS compared to HD-tDCS for a-tDCS (0-minutes) and c-tDCS (30-minutes). No significant changes were reported in SICI and ICF. These novel findings highlight current technical issues with HD-tDCS, suggesting future tDCS studies should utilise conventional tDCS to minimise intra-individual variability, ensuring tDCS after-effects are true changes in CSE and cortico-cortical excitability.

Acute Changes in Motor Cortical Excitability During Slow Oscillatory and Constant Anodal Transcranial Direct Current Stimulation

2009 ◽  
Vol 102 (4) ◽  
pp. 2303-2311 ◽  
Author(s):  
Til Ole Bergmann ◽  
Sergiu Groppa ◽  
Markus Seeger ◽  
Matthias Mölle ◽  
Lisa Marshall ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Slow Oscillation ◽  
Facilitatory Effect ◽  
Endogenous Rhythms ◽  
Direct Current Stimulation ◽  
On Line

Transcranial oscillatory current stimulation has recently emerged as a noninvasive technique that can interact with ongoing endogenous rhythms of the human brain. Yet, there is still little knowledge on how time-varied exogenous currents acutely modulate cortical excitability. In ten healthy individuals we used on-line single-pulse transcranial magnetic stimulation (TMS) to search for systematic shifts in corticospinal excitability during anodal sleeplike 0.8-Hz slow oscillatory transcranial direct current stimulation (so-tDCS). In separate sessions, we repeatedly applied 30-s trials (two blocks at 20 min) of either anodal so-tDCS or constant tDCS (c-tDCS) to the primary motor hand area during quiet wakefulness. Simultaneously and time-locked to different phase angles of the slow oscillation, motor-evoked potentials (MEPs) as an index of corticospinal excitability were obtained in the contralateral hand muscles 10, 20, and 30 s after the onset of tDCS. MEPs were also measured off-line before, between, and after both stimulation blocks to detect any lasting excitability shifts. Both tDCS modes increased MEP amplitudes during stimulation with an attenuation of the facilitatory effect toward the end of a 30-s tDCS trial. No phase-locking of corticospinal excitability to the exogenous oscillation was observed during so-tDCS. Off-line TMS revealed that both c-tDCS and so-tDCS resulted in a lasting excitability increase. The individual magnitude of MEP facilitation during the first tDCS trials predicted the lasting MEP facilitation found after tDCS. We conclude that sleep slow oscillation-like excitability changes cannot be actively imposed on the awake cortex with so-tDCS, but phase-independent on-line as well as off-line facilitation can reliably be induced.

scholarly journals Transcranial direct current stimulation treatment protocols: should stimulus intensity be constant or incremental over multiple sessions?

2013 ◽  
Vol 16 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Verònica Gálvez ◽  
Angelo Alonzo ◽  
Donel Martin ◽  
Colleen K. Loo
Keyword(s):  
Motor Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Constant Intensity ◽  
Treatment Protocols ◽  
Direct Current Stimulation ◽  
Before And After

Abstract Interest in transcranial direct current stimulation (tDCS) as a new tool in neuropsychiatry has led to the need to establish optimal treatment protocols. In an intra-individual randomized cross-over design, 11 healthy volunteers received five tDCS sessions to the left primary motor cortex on consecutive weekdays at a constant or gradually increasing current intensity, in two separate weeks of testing. Cortical excitability was assessed before and after tDCS at each session through peripheral electromyographic recordings of motor-evoked potentials. Both conditions led to significant cumulative increases in cortical excitability across the week but there were no significant differences between the two groups. Motor thresholds decreased significantly from Monday to Friday in both conditions. This study demonstrated that, in the motor cortex, administration of tDCS five times per week whether at a constant intensity or at a gradually increasing intensity was equally effective in increasing cortical excitability.

scholarly journals Bilateral Transcranial Direct Current Stimulation Modulates Activation-Induced Regional Blood Flow Changes during Voluntary Movement

2011 ◽  
Vol 31 (10) ◽  
pp. 2086-2095 ◽  
Author(s):  
Caroline Paquette ◽  
Michael Sidel ◽  
Basia A Radinska ◽  
Jean-Paul Soucy ◽  
Alexander Thiel
Keyword(s):  
Blood Flow ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Regional Blood Flow ◽  
Active Movement ◽  
Sham Stimulation ◽  
Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that induces changes in cortical excitability: anodal stimulation increases while cathodal stimulation reduces excitability. Imaging studies performed after unilateral stimulation have shown conflicting results regarding the effects of tDCS on surrogate markers of neuronal activity. The aim of this study was to directly measure these effects on activation-induced changes in regional cerebral blood flow (⊿rBF) using positron emission tomography (PET) during bilateral tDCS. Nine healthy subjects underwent repeated rCBF measurements with 15O-water and PET during a simple motor task while receiving tDCS or sham stimulation over the primary motor cortex (M1). Motor evoked potentials (MEPs) were also assessed before and after real and sham stimulation. During tDCS with active movement, ⊿rBF in M1 was significantly lower on the cathodal than the anodal side when compared with sham stimulation. This decrease in ⊿rBF was accompanied by a decrease in MEP amplitude on the cathodal side. No effect was observed on resting or activated rCBF relative to sham stimulation. We thus conclude that it is the interaction of cathodal tDCS with activation-induced ⊿rBF rather than the effect on resting or activated rCBF itself which constitutes the physiological imaging correlate of tDCS.

scholarly journals The effects of transcranial direct current stimulation on gait in patients with Parkinson’s disease: a systematic review

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Fateme Pol ◽  
Mohammad Ali Salehinejad ◽  
Hamzeh Baharlouei ◽  
Michael A. Nitsche
Keyword(s):  
Systematic Review ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Randomized Clinical Trials ◽  
Cortical Excitability ◽  
Experimental Studies ◽  
Gait Rehabilitation ◽  
Direct Current Stimulation

Abstract Background Gait problems are an important symptom in Parkinson’s disease (PD), a progressive neurodegenerative disease. Transcranial direct current stimulation (tDCS) is a neuromodulatory intervention that can modulate cortical excitability of the gait-related regions. Despite an increasing number of gait-related tDCS studies in PD, the efficacy of this technique for improving gait has not been systematically investigated yet. Here, we aimed to systematically explore the effects of tDCS on gait in PD, based on available experimental studies. Methods Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, PubMed, Web of Science, Scopus, and PEDro databases were searched for randomized clinical trials assessing the effect of tDCS on gait in patients with PD. Results Eighteen studies were included in this systematic review. Overall, tDCS targeting the motor cortex and supplementary motor area bilaterally seems to be promising for gait rehabilitation in PD. Studies of tDCS targeting the dorosolateral prefrontal cortex or cerebellum showed more heterogeneous results. More studies are needed to systematically compare the efficacy of different tDCS protocols, including protocols applying tDCS alone and/or in combination with conventional gait rehabilitation treatment in PD. Conclusions tDCS is a promising intervention approach to improving gait in PD. Anodal tDCS over the motor areas has shown a positive effect on gait, but stimulation of other areas is less promising. However, the heterogeneities of methods and results have made it difficult to draw firm conclusions. Therefore, systematic explorations of tDCS protocols are required to optimize the efficacy.

scholarly journals Gender-specific modulation of short-term neuroplasticity in the visual cortex induced by transcranial direct current stimulation

2008 ◽  
Vol 25 (1) ◽  
pp. 77-81 ◽  
Author(s):  
LEILA CHAIEB ◽  
ANDREA ANTAL ◽  
WALTER PAULUS
Keyword(s):  
Sex Differences ◽  
Visual Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Cortical Excitability ◽  
Gonadal Hormones ◽  
Study Data ◽  
Short Term ◽  
Direct Current Stimulation ◽  
Significant Difference

Transcranial direct current stimulation (tDCS) is a non-invasive method of modulating levels of cortical excitability. In this study, data gathered over a number of previously conducted experiments before and after tDCS, has been re-analyzed to investigate correlations between sex differences with respect to neuroplastic effects. Visual evoked potentials (VEPs), phosphene thresholds (PTs), and contrast sensitivity measurements (CSs) are used as indicators of the excitability of the primary visual cortex. The data revealed that cathodally induced excitability effects 10 min post stimulation with tDCS, showed no significant difference between genders. However, stimulation in the anodal direction revealed sex-specific effects: in women, anodal stimulation heightened cortical excitability significantly when compared to the age-matched male subject group. There was no significant difference between male and female subjects immediately after stimulation. These results indicate that sex differences exist within the visual cortex of humans, and may be subject to the influences of modulatory neurotransmitters or gonadal hormones which mirror short-term neuroplastic effects.

scholarly journals Comparison of repeated transcranial stimulation and transcranial direct-current stimulation on primary motor cortex excitability and inhibition: A pilot study

2018 ◽  
pp. 59-67 ◽  
Author(s):  
Vincent Cabibel ◽  
Makii Muthalib ◽  
Jérôme Froger ◽  
Stéphane Perrey
Keyword(s):  
Pilot Study ◽  
Motor Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
High Definition ◽  
Direct Current Stimulation ◽  
Motor Cortex Excitability ◽  
The Right

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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