Differences in high-definition transcranial direct current stimulation over the motor hotspot versus the premotor cortex on motor network excitability

AbstractThe effectiveness of transcranial direct current stimulation (tDCS) placed over the motor hotspot (thought to represent the primary motor cortex (M1)) to modulate motor network excitability is highly variable. The premotor cortex—particularly the dorsal premotor cortex (PMd)—may be a promising alternative target to more effectively modulate motor excitability, as it influences motor control across multiple pathways, one independent of M1 and one with direct, modulating connections to M1. This double-blind, placebo-controlled study aimed to differentially excite motor and premotor regions using high-definition tDCS (HD-tDCS) with concurrent functional magnetic resonance imaging (fMRI). HD-tDCS applied over either the motor hotspot or the premotor cortex demonstrated high inter-individual variability in changes on cortical motor excitability. However, HD-tDCS over the premotor cortex led to a higher number of responders and greater changes in local fMRI-based complexity than HD-tDCS over the motor hotspot. Furthermore, an analysis of individual motor hotspot anatomical locations revealed that, in more than half of the participants, the motor hotspot is not located over anatomical M1 boundaries, despite using a canonical definition of the motor hotspot. This heterogeneity in stimulation site may contribute to the variability of tDCS results. Altogether, these findings provide new considerations to enhance tDCS reliability.

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Differences in high-definition transcranial direct current stimulation over the motor hotspot versus the premotor cortex on motor network excitability

Scientific Reports ◽

10.1038/s41598-019-53985-7 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 5

Author(s):

Stephanie Lefebvre ◽

Kay Jann ◽

Allie Schmiesing ◽

Kaori Ito ◽

Mayank Jog ◽

...

Keyword(s):

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Premotor Cortex ◽

High Definition ◽

Double Blind ◽

Promising Alternative ◽

Direct Current Stimulation ◽

Motor Network ◽

Motor Excitability

AbstractThe effectiveness of transcranial direct current stimulation (tDCS) placed over the motor hotspot (thought to represent the primary motor cortex (M1)) to modulate motor network excitability is highly variable. The premotor cortex—particularly the dorsal premotor cortex (PMd)—may be a promising alternative target to reliably modulate motor excitability, as it influences motor control across multiple pathways, one independent of M1 and one with direct connections to M1. This double-blind, placebo-controlled preliminary study aimed to differentially excite motor and premotor regions using high-definition tDCS (HD-tDCS) with concurrent functional magnetic resonance imaging (fMRI). HD-tDCS applied over either the motor hotspot or the premotor cortex demonstrated high inter-individual variability in changes on cortical motor excitability. However, HD-tDCS over the premotor cortex led to a higher number of responders and greater changes in local fMRI-based complexity than HD-tDCS over the motor hotspot. Furthermore, an analysis of individual motor hotspot anatomical locations revealed that, in more than half of the participants, the motor hotspot is not located over anatomical M1 boundaries, despite using a canonical definition of the motor hotspot. This heterogeneity in stimulation site may contribute to the variability of tDCS results. Altogether, these preliminary findings provide new considerations to enhance tDCS reliability.

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

Movement & Sport Sciences - Science & Motricité ◽

10.1051/sm/2018001 ◽

2018 ◽

pp. 59-67 ◽

Cited By ~ 1

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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Transcranial Direct Current Stimulation (tDCS) in Unilateral Cerebral Palsy: A Pilot Study of Motor Effect

Neural Plasticity ◽

10.1155/2019/2184398 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Emanuela Inguaggiato ◽

Nadia Bolognini ◽

Simona Fiori ◽

Giovanni Cioni

Keyword(s):

Cerebral Palsy ◽

Pilot Study ◽

Upper Limb ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Controlled Study ◽

Anodal Tdcs ◽

Direct Current Stimulation ◽

Unilateral Cerebral Palsy

Transcranial Direct Current Stimulation (tDCS) is an emerging tool to improve upper limb motor functions after stroke acquired in adulthood; however, there is a paucity of reports on its efficacy for upper limb motor rehabilitation in congenital or early-acquired stroke. In this pilot study we have explored, for the first time, the immediate effects, and their short-term persistence, of a single application of anodal tDCS on chronic upper limb motor disorders in children and young individuals with Unilateral Cerebral Palsy (UCP). To this aim, in a crossover sham-controlled study, eight subjects aged 10-28 years with UCP underwent two sessions of active and sham tDCS. Anodal tDCS (1.5 mA, 20 min) was delivered over the primary motor cortex (M1) of the ipsilesional hemisphere. Results showed, only following the active stimulation, an immediate improvement in unimanual gross motor dexterity of hemiplegic, but not of nonhemiplegic, hand in Box and Block test (BBT). Such improvement remained stable for at least 90 minutes. Performance of both hands in Hand Grip Strength test was not modified by anodal tDCS. Improvement in BBT was unrelated to participants’ age or lesion size, as revealed by MRI data analysis. No serious adverse effects occurred after tDCS; some mild and transient side effects (e.g., headache, tingling, and itchiness) were reported in a limited number of cases. This study provides an innovative contribution to scientific literature on the efficacy and safety of anodal tDCS in UCP. This trial is registered with NCT03137940.

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High-definition transcranial direct-current stimulation of the right M1 further facilitates left M1 excitability during crossed facilitation

Journal of Neurophysiology ◽

10.1152/jn.00861.2017 ◽

2018 ◽

Vol 119 (4) ◽

pp. 1266-1272 ◽

Cited By ~ 12

Author(s):

Vincent Cabibel ◽

Makii Muthalib ◽

Wei-Peng Teo ◽

Stephane Perrey

Keyword(s):

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Single Pulse ◽

High Definition ◽

Maximum Voluntary Isometric Contraction ◽

Direct Current Stimulation ◽

The Right ◽

Stimulation Of

The crossed-facilitation (CF) effect refers to when motor-evoked potentials (MEPs) evoked in the relaxed muscles of one arm are facilitated by contraction of the opposite arm. The aim of this study was to determine whether high-definition transcranial direct-current stimulation (HD-tDCS) applied to the right primary motor cortex (M1) controlling the left contracting arm [50% maximum voluntary isometric contraction (MVIC)] would further facilitate CF toward the relaxed right arm. Seventeen healthy right-handed subjects participated in an anodal and cathodal or sham HD-tDCS session of the right M1 (2 mA for 20 min) separated by at least 48 h. Single-pulse transcranial magnetic stimulation (TMS) was used to elicit MEPs and cortical silent periods (CSPs) from the left M1 at baseline and 10 min into and after right M1 HD-tDCS. At baseline, compared with resting, CF (i.e., right arm resting, left arm 50% MVIC) increased left M1 MEP amplitudes (+97%) and decreased CSPs (−11%). The main novel finding was that right M1 HD-tDCS further increased left M1 excitability (+28.3%) and inhibition (+21%) from baseline levels during CF of the left M1, with no difference between anodal and cathodal HD-tDCS sessions. No modulation of CSP or MEP was observed during sham HD-tDCS sessions. Our findings suggest that CF of the left M1 combined with right M1 anodal or cathodal HD-tDCS further facilitated interhemispheric interactions during CF from the right M1 (contracting left arm) toward the left M1 (relaxed right arm), with effects on both excitatory and inhibitory processing. NEW & NOTEWORTHY This study shows modulation of the nonstimulated left M1 by right M1 HD-tDCS combined with crossed facilitation, which was probably achieved through modulation of interhemispheric interactions.

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Effect of transcranial direct current stimulation in the first weeks after stroke: a preliminary study

10.5327/1516-3180.252 ◽

2021 ◽

Author(s):

Marcela Tengler Carvalho Takahashi ◽

Paulo Rodrigo Bázan ◽

Joana Bisol Balardin ◽

Danielle de Sá Boasquevisque ◽

Edson Amaro Júnior ◽

...

Keyword(s):

Motor Cortex ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Motor Performance ◽

Sham Group ◽

Primary Motor Cortex ◽

Premotor Cortex ◽

Group Differences ◽

Direct Current Stimulation ◽

Cathodal Tdcs

Background: There is limited information about effects of transcranial Direct Current Stimulation(tDCS), delivered within the first weeks post-stroke, on performance of the paretic upper limb and on connectivity between motor areas in the affected and unaffected hemispheres. Objectives: We compared changes in Fugl-Meyer Assessment of Motor Recovery(FMA) scores, connectivity between the primary motor cortex of the unaffected(M1UH) and the affected hemisphere(M1AH), as well as between M1UH and the premotor cortex of the unaffected hemisphere(PMUH) before and after 6 sessions of cathodal tDCS targeting the primary motor cortex of the unaffected hemisphere(M1UH) early after stroke in 13 patients. Methods: This hypothesis-generating substudy was a randomized parallel, two-arm, double-blind, sham-controlled clinical trial performed at the Albert Einstein Hospital. Subjects were randomized active(N=6) or sham(N=7) groups. Results: Clinically relevant differences in FMA scores(≥ 9 points) were observed more often in the sham than in the active group. Between-group differences in changes in FMA scores were not statistically significant(Mann-Whitney test, p=0.133) but the effect size was -0.619(rank biserial correlation). Connectivity measures(Fisher’s z- transform of ROI-to-ROI correlations) between M1AH-M1UH increased in 5/6 participants in the active, and in 2/7 in the sham group after treatment. Between-group differences in changes in connectivity(M1UH-M1AH or PMUH-M1AH) were not statistically significant. In contrast with M1AH-M1UH connectivity, improvements in motor performance were more frequent in the active than in the sham group. Conclusions: Effects of cathodal tDCS on motor performance and on Resting-state Functional Magnetic Resonance Imaging may have distinct underpinnings in subjects at an early stage after stroke.

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Effects of Transcranial Direct Current Stimulation on Apraxia of Speech and Cortical Activation in Patients With Stroke: A Randomized Sham-Controlled Study

American Journal of Speech-Language Pathology ◽

10.1044/2019_ajslp-19-0069 ◽

2019 ◽

Vol 28 (4) ◽

pp. 1625-1637 ◽

Cited By ~ 1

Author(s):

Jie Wang ◽

Dongyu Wu ◽

Yinan Cheng ◽

Weiqun Song ◽

Ying Yuan ◽

...

Keyword(s):

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Approximate Entropy ◽

Cortical Activation ◽

Controlled Study ◽

Broca’S Area ◽

Apraxia Of Speech ◽

Broca's Area ◽

Direct Current Stimulation

Purpose The study aims to investigate, using anodal transcranial direct current stimulation (A-tDCS), over which site, the left lip region of primary motor cortex (M1) or the Broca's area, there would be better recovery from apraxia of speech (AoS) in patients with poststroke aphasia and to examine for altered activation in speech-related areas after tDCS with nonlinear electroencephalography (EEG). Method Fifty-two patients with AoS were randomized into A-tDCS over the left M1 (A-tDCS-M1), Broca's area, and sham tDCS groups who underwent 10 sessions of tDCS and speech treatment for 5 days. The EEG nonlinear index of approximate entropy was calculated for 6 subjects in each group before and after treatment. Results After treatment, the change in speech-language performance improved more significantly in the A-tDCS-M1 group than the other 2 groups ( p < .05). EEG approximate entropy indicated that both A-tDCS groups could activate the stimulated sites; the improvement in the A-tDCS-M1 group was correlated with high activation in the dorsal lateral prefrontal cortex and Broca's areas of the left hemisphere in addition to the stimulated site. Conclusion A-tDCS over the left M1 can improve the speech function in patients with poststroke aphasia and severe AoS and excite and recruit more areas in the motor speech network.

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Differential effects of primary motor cortex and cerebellar transcranial direct current stimulation on motor learning in healthy individuals: A randomized double-blind sham-controlled study

Neuroscience Research ◽

10.1016/j.neures.2016.06.003 ◽

2016 ◽

Vol 112 ◽

pp. 10-19 ◽

Cited By ~ 25

Author(s):

F. Ehsani ◽

A.H. Bakhtiary ◽

S. Jaberzadeh ◽

A. Talimkhani ◽

A. Hajihasani

Keyword(s):

Motor Cortex ◽

Motor Learning ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Controlled Study ◽

Healthy Individuals ◽

Double Blind ◽

Differential Effects ◽

Direct Current Stimulation

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Utilizing Transcranial Direct Current Stimulation to Enhance Laparoscopic Technical Skills Training: A Randomized Controlled Trial

10.1101/455329 ◽

2018 ◽

Author(s):

Morgan L. Cox ◽

Zhi-De Deng ◽

Hannah Palmer ◽

Amanda Watts ◽

Lysianne Beynel ◽

...

Keyword(s):

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Skill Training ◽

Technical Skills ◽

Skills Training ◽

Controlled Study ◽

Laparoscopic Skill ◽

Direct Current Stimulation ◽

Post Test

AbstractThis study aimed to test the efficacy of transcranial direct current stimulation (tDCS) during laparoscopic skill training to determine if it has the capacity to accelerate technical skill acquisition. tDCS is a non-invasive brain stimulation technique that delivers constant, low electrical current resulting in changes to cortical excitability and prior work suggests it may enhance motor learning. We evaluate for the first time the potential of tDCS, coupled with motor skill training, to accelerate the development of laparoscopic technical skills. In this pre-registered, double-blinded and sham-controlled study, 60 healthy subjects were randomized into sham or active tDCS in either bilateral primary motor cortex (bM1) or supplementary motor area (SMA) electrode configurations. All subjects practiced the Fundamental of Laparoscopic Surgery Peg Transfer Task during a pre-test, six 20-minute training sessions, and a post-test. The primary outcome was change in laparoscopic skill performance over time, quantified by improvement in performance according to a seconds-per-object calculated score accounting for errors. Sixty participants were randomized equally into the three training cohorts (active bM1, active SMA, sham). The active groups had significantly greater improvement in performance from pre-test to post-test compared to the sham groups (108 vs 76 seconds, p = 0.018). Both bM1 and SMA active cohorts had significantly greater improvement in learning (p < 0.01), achieving the same skill level in 4 sessions compared to the 6 sessions required of the sham cohort. The SMA cohort had more variability in performance compared to the bM1 and control cohorts. Laparoscopic skill training with active, bM1 or SMA, tDCS exhibited significantly greater learning relative to training with sham tDCS. The potential for tDCS to enhance the training of surgical skills merits further investigation to determine if these preliminary results may be replicated.

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