TMS waveform and current direction

2012 ◽  
Author(s):  
Martin Sommer ◽  
Walter Paulus
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Clinical Relevance ◽  
Magnetic Stimulation ◽  
Corticospinal Excitability ◽  
Current Direction ◽  
Physiological Basis ◽  
Test Pulse ◽  
Repetitive Tms ◽  
The Difference ◽  
Millisecond Range

This article introduces the difference between biphasic and monophasic transcranial magnetic stimulation (TMS). Waveform and current direction determine the effectiveness of TMS in humans. The alternating use of mono and biphasic pulses as conditioning or test pulse has so far not been possible. Since pulses of different waveform or orientation cannot be applied through the same coil at an interval in the millisecond range, using two different coils could be a feasible approach. This article brings in the concept of repetitive TMS (rTMS). Although clinical relevance is lacking, there is plenty of interesting data available for rTMS. Both pulse configuration and current direction affect the modulation of corticospinal excitability induced by rTMS. The effects during rTMS may differ from those outlasting rTMS. Further studies are needed to confirm the histological and physiological basis for these differences, and to clarify their clinical relevance.

Evaluation of corticobulbar and corticospinal excitability in developmental stuttering: the navigated transcranial magnetic stimulation study

2015 ◽  
Vol 8 (2) ◽  
pp. 317-318 ◽  
Author(s):  
Maja Rogić Vidaković ◽  
Marina Zmajević Schönwald ◽  
Tomislav Jurić ◽  
Nikola Erceg ◽  
Andreja Bubić ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Corticospinal Excitability ◽  
Navigated Transcranial Magnetic Stimulation ◽  
Developmental Stuttering

scholarly journals The Reliability of Transcranial Magnetic Stimulation-Derived Corticomotor Inhibition as a Brain Health Evaluation Tool in Soccer Players

2022 ◽  
Vol 8 (1) ◽  
Author(s):  
Thomas G. Di Virgilio ◽  
Magdalena Ietswaart ◽  
Ragul Selvamoorthy ◽  
Angus M. Hunter
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Rectus Femoris ◽  
Corticospinal Excitability ◽  
Soccer Players ◽  
Group Differences ◽  
Evaluation Tool ◽  
Brain Health ◽  
Actual Measurement ◽  
Head Impacts

Abstract Background The suitability of corticomotor inhibition and corticospinal excitability to measure brain health outcomes and recovery of sport-related head impact (concussion and subconcussion) depends on good inter-day reliability, which is evaluated in this study. Transcranial magnetic stimulation (TMS) reliability in soccer players is assessed by comparing soccer players, for whom reliability on this measure may be reduced due to exposure to head impacts, to generally active individuals not engaged in contact sport. Methods TMS-derived corticomotor inhibition and corticospinal excitability were recorded from the rectus femoris muscle during two testing sessions, spaced 1–2 weeks apart in 19 soccer players (SOC—age 22 ± 3 years) and 20 generally active (CON—age 24 ± 4 years) healthy volunteers. Inter-day reliability between the two time points was quantified by using intra-class correlation coefficients (ICC). Intra-group reliability and group differences on actual measurement values were also explored. Results Good inter-day reliability was evident for corticomotor inhibition (ICCSOC = 0.61; ICCCON = 0.70) and corticospinal excitability (ICCSOC = 0.59; ICCCON = 0.70) in both generally active individuals and soccer players routinely exposed to sport-related head impacts. Corticomotor inhibition showed lower coefficients of variation than excitability for both groups (InhibSOC = 15.2%; InhibCON = 9.7%; ExcitabSOC = 41.6%; ExcitabCON = 39.5%). No group differences between soccer players and generally active individuals were found on the corticomotor inhibition value (p > 0.05), but levels of corticospinal excitability were significantly lower in soccer players (45.1 ± 20.8 vs 85.4 ± 6.2%Mmax, p < 0.0001). Corticomotor inhibition also showed excellent inter-rater reliability (ICC = 0.87). Conclusions Corticomotor inhibition and corticospinal excitability are stable and maintain good degrees of reliability when assessed over different days in soccer players, despite their routine exposure to head impacts. However, based on intra-group reliability and group differences of the levels of excitability, we conclude that corticomotor inhibition is best suited for the evaluation of neuromuscular alterations associated with head impacts in contact sports.

scholarly journals Corticospinal correlates of fast and slow adaptive processes in motor learning

2018 ◽  
Vol 120 (4) ◽  
pp. 2011-2019 ◽  
Author(s):  
Adjmal M. E. Sarwary ◽  
Miles Wischnewski ◽  
Dennis J. L. G. Schutter ◽  
Luc P. J. Selen ◽  
W. Pieter Medendorp
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Motor Learning ◽  
Magnetic Stimulation ◽  
Corticospinal Excitability ◽  
Behavioral Observations ◽  
Adaptive Processes ◽  
Adaptation Processes ◽  
Adaptation Task ◽  
Adaptation Model

Recent computational theories and behavioral observations suggest that motor learning is supported by multiple adaptation processes, operating on different timescales, but direct neural evidence is lacking. We tested this hypothesis by applying transcranial magnetic stimulation over motor cortex in 16 human subjects during a validated reach adaptation task. Motor-evoked potentials (MEPs) and cortical silent periods (CSPs) were recorded from the biceps brachii to assess modulations of corticospinal excitability as indices for corticospinal plasticity. Guided by a two-state adaptation model, we show that the MEP reflects an adaptive process that learns quickly but has poor retention, while the CSP correlates with a process that responds more slowly but retains information well. These results provide a physiological link between models of motor learning and distinct changes in corticospinal excitability. Our findings support the relationship between corticospinal gain modulations and the adaptive processes in motor learning. NEW & NOTEWORTHY Computational theories and behavioral observations suggest that motor learning is supported by multiple adaptation processes, but direct neural evidence is lacking. We tested this hypothesis by applying transcranial magnetic stimulation over human motor cortex during a reach adaptation task. Guided by a two-state adaptation model, we show that the motor-evoked potential reflects a process that adapts and decays quickly, whereas the cortical silent period reflects slow adaptation and decay.

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