Browsing by Subject "Transcranial magnetic stimulation"

Now showing 1 - 7 of 7
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    Cortical Representation and Excitability Increases for a Thenar Muscle Mediate Improvement in Short-Term Cellular Phone Text Messaging Ability
    (MDPI, 2021-03-23) Meek, Anthony W.; Perez, Joselyn; Poston, Brach; Riley, Zachary A.; Health Sciences, School of Health and Human Sciences
    Cortical representations expand during skilled motor learning. We studied a unique model of motor learning with cellular phone texting, where the thumbs are used exclusively to interact with the device and the prominence of use can be seen where 3200 text messages are exchanged a month in the 18-24 age demographic. The purpose of the present study was to examine the motor cortex representation and input-output (IO) recruitment curves of the abductor pollicis brevis (APB) muscle of the thumb and the ADM muscle with transcranial magnetic stimulation (TMS), relative to individuals' texting abilities and short-term texting practice. Eighteen individuals performed a functional texting task (FTT) where we scored their texting speed and accuracy. TMS was then used to examine the cortical volumes and areas of activity in the two muscles and IO curves were constructed to measure excitability. Subjects also performed a 10-min practice texting task, after which we repeated the cortical measures. There were no associations between the cortical measures and the FTT scores before practice. However, after practice the APB cortical map expanded and excitability increased, whereas the ADM map constricted. The increase in the active cortical areas in APB correlated with the improvement in the FTT score. Based on the homogenous group of subjects that were already good at texting, we conclude that the cortical representations and excitability for the thumb muscle were already enlarged and more receptive to changes with short-term practice, as noted by the increase in FTT performance after 10-min of practice.
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    Exploring the Influence of Inter-Trial Interval on the Assessment of Short-Interval Intracortical Inhibition
    (MDPI, 2024-06-25) de Albuquerque, Lidio Lima; Pantovic, Milan; Wilkins, Erik W.; Morris, Desiree; Clingo, Mitchell; Boss, Sage; Riley, Zachary A.; Poston, Brach; Exercise & Kinesiology, School of Health and Human Sciences
    Short-interval intracortical inhibition (SICI) is a common paired-pulse transcranial magnetic stimulation (TMS) measure used to assess primary motor cortex (M1) interneuron activity in healthy populations and in neurological disorders. Many of the parameters of TMS stimulation to most accurately measure SICI have been determined. However, one TMS parameter that has not been investigated is the time between SICI trials (termed inter-trial interval; ITI). This is despite a series of single-pulse TMS studies which have reported that motor evoked potential (MEP) amplitude were suppressed for short, but not long ITIs in approximately the initial ten trials of a TMS block of 20–30 trials. The primary purpose was to examine the effects of ITI on the quantification of SICI at rest. A total of 23 healthy adults completed an experimental session that included four SICI trial blocks. Each block utilized a different ITI (4, 6, 8, and 10 s) and was comprised of a total of 26 SICI trials divided into three epochs. ANOVA revealed that the main effects for ITI and epoch as well as their interaction were all non-statistically significant for SICI. We conclude that the shorter (4–6 s) ITIs used in studies investigating SICI should not alter the interpretation of M1 activity, while having the advantages of being more comfortable to participants and reducing the experimental time needed to evaluate perform single and paired-pulse TMS experiments.
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    Left prefrontal transcranial magnetic stimulation for treatment-resistant depression in adolescents: a double-blind, randomized, sham-controlled trial
    (Springer Nature, 2021) Croarkin, Paul E.; Elmaadawi, Ahmed Z.; Aaronson, Scott T.; Schrodt, G. Randolph, Jr.; Holbert, Richard C.; Verdoliva, Sarah; Heart, Karen L.; Demitrack, Mark A.; Strawn, Jeffrey R.; Psychiatry, School of Medicine
    Treatment-resistant depression (TRD) is prevalent and associated with a substantial psychosocial burden and mortality. There are few prior studies of interventions for TRD in adolescents. This was the largest study to date examining the feasibility, safety, and efficacy of 10-Hz transcranial magnetic stimulation (TMS) for adolescents with TRD. Adolescents with TRD (aged 12-21 years) were enrolled in a randomized, sham-controlled trial of TMS across 13 sites. Treatment resistance was defined as an antidepressant treatment record level of 1 to 4 in a current episode of depression. Intention-to-treat patients (n = 103) included those randomly assigned to active NeuroStar TMS monotherapy (n = 48) or sham TMS (n = 55) for 30 daily treatments over 6 weeks. The primary outcome measure was change in the Hamilton Depression Rating Scale (HAM-D-24) score. After 6 weeks of blinded treatment, improvement in the least-squares mean (SE) HAM-D-24 scores were similar between the active (-11.1 [2.03]) and sham groups (-10.6 [2.00]; P = 0.8; difference [95% CI], - 0.5 [-4.2 to 3.3]). Response rates were 41.7% in the active group and 36.4% in the sham group (P = 0.6). Remission rates were 29.2% in the active group and 29.0% in the sham group (P = 0.95). There were no new tolerability or safety signals in adolescents. Although TMS treatment produced a clinically meaningful change in depressive symptom severity, this did not differ from sham treatment. Future studies should focus on strategies to reduce the placebo response and examine the optimal dosing of TMS for adolescents with TRD.
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    Motor Learning in a Complex Motor Task Is Unaffected by Three Consecutive Days of Transcranial Alternating Current Stimulation
    (MDPI, 2024-07-23) Wilkins, Erik W.; Pantovic, Milan; Noorda, Kevin J.; Premyanov, Mario I.; Boss, Rhett; Davidson, Ryder; Hagans, Taylor A.; Riley, Zachary A.; Poston, Brach; Exercise & Kinesiology, School of Health and Human Sciences
    Transcranial alternating current stimulation (tACS) delivered to the primary motor cortex (M1) can increase cortical excitability, entrain neuronal firing patterns, and increase motor skill acquisition in simple motor tasks. The primary aim of this study was to assess the impact of tACS applied to M1 over three consecutive days of practice on the motor learning of a challenging overhand throwing task in young adults. The secondary aim was to examine the influence of tACS on M1 excitability. This study implemented a double-blind, randomized, SHAM-controlled, between-subjects experimental design. A total of 24 healthy young adults were divided into tACS and SHAM groups and performed three identical experimental sessions that comprised blocks of overhand throwing trials of the right dominant arm concurrent with application of tACS to the left M1. Performance in the overhand throwing task was quantified as the endpoint error. Motor evoked potentials (MEPs) were assessed in the right first dorsal interosseus (FDI) muscle with transcranial magnetic stimulation (TMS) to quantify changes in M1 excitability. Endpoint error was significantly decreased in the post-tests compared with the pre-tests when averaged over the three days of practice (p = 0.046), but this decrease was not statistically significant between the tACS and SHAM groups (p = 0.474). MEP amplitudes increased from the pre-tests to the post-tests (p = 0.003), but these increases were also not different between groups (p = 0.409). Overall, the main findings indicated that tACS applied to M1 over multiple days does not enhance motor learning in a complex task to a greater degree than practice alone (SHAM).
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    Non-Dominant Hemisphere Excitability Is Unaffected during and after Transcranial Direct Current Stimulation of the Dominant Hemisphere
    (MDPI, 2024-07-12) Wilkins, Erik W.; Young, Richard J.; Houston, Daniel; Kawana, Eric; Lopez Mora, Edgar; Sunkara, Meghana S.; Riley, Zachary A.; Poston, Brach; Exercise & Kinesiology, School of Health and Human Sciences
    Transcranial direct current stimulation (tDCS) increases primary motor cortex (M1) excitability and improves motor performance when applied unilaterally to the dominant hemisphere. However, the influence of tDCS on contralateral M1 excitability both during and after application has not been quantified. The purpose was to determine the influence of tDCS applied to the dominant M1 on the excitability of the contralateral non-dominant M1. This study employed a double-blind, randomized, SHAM-controlled, within-subject crossover experimental design. Eighteen young adults performed two experimental sessions (tDCS, SHAM) in counterbalanced order separated by a one-week washout. Transcranial magnetic stimulation (TMS) was used to quantify the excitability of the contralateral M1 to which anodal tDCS was applied for 20 min with a current strength of 1 mA. Motor evoked potential (MEP) amplitudes were assessed in 5 TMS test blocks (Pre, D5, D10, D15, and Post). The Pre and Post TMS test blocks were performed immediately before and after tDCS application, whereas the TMS test blocks performed during tDCS were completed at the 5, 10, and 15 min stimulation timepoints. MEPs were analyzed with a 2 condition (tDCS, SHAM) × 5 test (Pre, D5, D10, D15, Post) within-subject ANOVA. The main effect for condition (p = 0.213), the main effect for test (p = 0.502), and the condition × test interaction (p = 0.860) were all not statistically significant. These results indicate that tDCS does not modulate contralateral M1 excitability during or immediately after application, at least under the current set of common tDCS parameters of stimulation.
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    The Influence of Different Inter-Trial Intervals on the Quantification of Intracortical Facilitation in the Primary Motor Cortex
    (MDPI, 2023-11-02) Pantovic, Milan; Boss, Rhett; Noorda, Kevin J.; Premyanov, Mario I.; Aynlender, Daniel G.; Wilkins, Erik W.; Boss, Sage; Riley, Zachary A.; Poston, Brach; Exercise & Kinesiology, School of Health and Human Sciences
    Intracortical facilitation (ICF) is a paired-pulse transcranial magnetic stimulation (TMS) measurement used to quantify interneuron activity in the primary motor cortex (M1) in healthy populations and motor disorders. Due to the prevalence of the technique, most of the stimulation parameters to optimize ICF quantification have been established. However, the underappreciated methodological issue of the time between ICF trials (inter-trial interval; ITI) has been unstandardized, and different ITIs have never been compared in a paired-pulse TMS study. This is important because single-pulse TMS studies have found motor evoked potential (MEP) amplitude reductions over time during TMS trial blocks for short, but not long ITIs. The primary purpose was to determine the influence of different ITIs on the measurement of ICF. Twenty adults completed one experimental session that involved 4 separate ICF trial blocks with each utilizing a different ITI (4, 6, 8, and 10 s). Two-way ANOVAs indicated no significant ITI main effects for test MEP amplitudes, condition-test MEP amplitudes, and therefore ICF. Accordingly, all ITIs studied provided nearly identical ICF values when averaged over entire trial blocks. Therefore, it is recommended that ITIs of 4–6 s be utilized for ICF quantification to optimize participant comfort and experiment time efficiency.
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    Transcranial Direct Current Stimulation of Primary Motor Cortex over Multiple Days Improves Motor Learning of a Complex Overhand Throwing Task
    (MDPI, 2023-10-10) Pantovic, Milan; Lima de Albuquerque, Lidio; Mastrantonio, Sierra; Pomerantz, Austin S.; Wilkins, Erik W.; Riley, Zachary A.; Guadagnoli, Mark A.; Poston, Brach; Exercise & Kinesiology, School of Health and Human Sciences
    Transcranial direct current stimulation (tDCS) applied to the primary motor cortex (M1) improves motor learning in relatively simple motor tasks performed with the hand and arm. However, it is unknown if tDCS can improve motor learning in complex motor tasks involving whole-body coordination with significant endpoint accuracy requirements. The primary purpose was to determine the influence of tDCS on motor learning over multiple days in a complex over-hand throwing task. This study utilized a double-blind, randomized, SHAM-controlled, between-subjects experimental design. Forty-six young adults were allocated to either a tDCS group or a SHAM group and completed three experimental sessions on three consecutive days at the same time of day. Each experimental session was identical and consisted of overhand throwing trials to a target in a pre-test block, five practice blocks performed simultaneously with 20 min of tDCS, and a post-test block. Overhand throwing performance was quantified as the endpoint error. Transcranial magnetic stimulation was used to obtain motor-evoked potentials (MEPs) from the first dorsal interosseus muscle to quantify changes in M1 excitability due to tDCS. Endpoint error significantly decreased over the three days of practice in the tDCS group but not in the SHAM group. MEP amplitude significantly increased in the tDCS group, but the MEP increases were not associated with increases in motor learning. These findings indicate that tDCS applied over multiple days can improve motor learning in a complex motor tasks in healthy young adults.