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Hamel R, Demers O, Boileau C, Roy ML, Théoret H, Bernier PM, Lepage JF. The neurobiological markers of acute alcohol's subjective effects in humans. Neuropsychopharmacology 2022; 47:2101-2110. [PMID: 35701548 PMCID: PMC9556716 DOI: 10.1038/s41386-022-01354-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/21/2022] [Accepted: 05/24/2022] [Indexed: 12/21/2022]
Abstract
The ingestion of alcohol yields acute biphasic subjective effects: stimulation before sedation. Despite their predictive relevance to the development of alcohol use disorders (AUD), the neurobiological markers accounting for the biphasic effects of alcohol remain poorly understood in humans. Informed by converging lines of evidence, this study tested the hypothesis that alcohol ingestion acutely increases gamma-aminobutyric acid (GABA)-mediated inhibition, which would positively and negatively predict the feeling of stimulation and sedation, respectively. To do so, healthy participants (n = 20) ingested a single dose of 94% ABV alcohol (males: 1.0 ml/kg; females: 0.85 ml/kg) in a randomized placebo-controlled cross-over design. The alcohol's biphasic effects were assessed with the Brief-Biphasic Alcohol Effects Scale, and non-invasive neurobiological markers were measured with transcranial magnetic stimulation, before and every 30 min (up to 120 min) after the complete ingestion of the beverage. Results showed that acute alcohol ingestion selectively increased the duration of the cortical silent period (CSP) as compared to placebo, suggesting that alcohol increases non-specific GABAergic inhibition. Importantly, CSP duration positively and negatively predicted increases in the feeling of stimulation and sedation, respectively, suggesting that stimulation emerges as GABAergic inhibition increases and that sedation emerges as GABAergic inhibition returns to baseline values. Overall, these results suggest that modulations of GABAergic inhibition are central to the acute biphasic subjective effects of alcohol, providing a potential preventive target to curb the progression of at-risk individuals to AUD.
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Affiliation(s)
- Raphael Hamel
- Département de kinanthropologie, Faculté des sciences de l'activité physique, Université de Sherbrooke, Sherbrooke, QC, Canada
- Département de pédiatrie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Olivier Demers
- Département de pédiatrie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Camille Boileau
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Marie-Laurence Roy
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Hugo Théoret
- Département de psychologie, Faculté des arts et sciences, Université de Montréal, Montreal, QC, Canada
| | - Pierre-Michel Bernier
- Département de kinanthropologie, Faculté des sciences de l'activité physique, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Jean-Francois Lepage
- Département de pédiatrie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada.
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Identifying novel biomarkers with TMS-EEG - Methodological possibilities and challenges. J Neurosci Methods 2022; 377:109631. [PMID: 35623474 DOI: 10.1016/j.jneumeth.2022.109631] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 05/09/2022] [Accepted: 05/21/2022] [Indexed: 12/17/2022]
Abstract
Biomarkers are essential for understanding the underlying pathologies in brain disorders and for developing effective treatments. Combined transcranial magnetic stimulation and electroencephalography (TMS-EEG) is an emerging neurophysiological tool that can be used for biomarker development. This method can identify biomarkers associated with the function and dynamics of the inhibitory and excitatory neurotransmitter systems and effective connectivity between brain areas. In this review, we outline the current state of the TMS-EEG biomarker field by summarizing the existing protocols and the possibilities and challenges associated with this methodology.
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Helling RM, Shmuely S, Bauer PR, Tolner EA, Visser GH, Thijs RD. Tracking cortical excitability dynamics with transcranial magnetic stimulation in focal epilepsy. Ann Clin Transl Neurol 2022; 9:540-551. [PMID: 35297209 PMCID: PMC8994988 DOI: 10.1002/acn3.51535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 11/05/2022] Open
Abstract
INTRODUCTION The lack of reliable biomarkers constrain epilepsy management. We assessed the potential of repeated transcranial magnetic stimulation with electromyography (TMS-EMG) to track dynamical changes in cortical excitability on a within-subject basis. METHODS We recruited people with refractory focal epilepsy who underwent video-EEG monitoring and drug tapering as part of the presurgical evaluation. We performed daily TMS-EMG measurements with additional postictal assessments 1-6 h following seizures to assess resting motor threshold (rMT), and motor evoked potentials (MEPs) with single- and paired-pulse protocols. Anti-seizure medication (ASM) regimens were recorded for the day before each measurement and expressed in proportion to the dosage before tapering. Additional measurements were performed in healthy controls to evaluate day-to-day rMT variability. RESULTS We performed 77 (58 baseline, 19 postictal) measurements in 16 people with focal epilepsy and 35 in seven healthy controls. Controls showed minimal day-to-day rMT variation. Withdrawal of ASMs was associated with a lower rMT without affecting MEPs of single- and paired-pulse TMS-EMG paradigms. Postictal measurements following focal to bilateral tonic-clonic seizures demonstrated unaltered rMT and increased short interval intracortical inhibition, while measurements following focal seizures with impaired awareness showed decreased rMT's and reduced short and long interval intracortical inhibition. CONCLUSION Serial within-subject rMT measurements yielded reproducible, stable results in healthy controls. ASM tapering and seizures had distinct effects on TMS-EMG excitability indices in people with epilepsy. Drug tapering decreased rMT, indicating increased overall corticospinal excitability, whereas seizures affected intracortical inhibition with contrasting effects between seizure types.
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Affiliation(s)
- Robert M Helling
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Sharon Shmuely
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands.,NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, UK
| | - Prisca R Bauer
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center Freiburg, Germany
| | - Else A Tolner
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Gerhard H Visser
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Roland D Thijs
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands.,NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, UK.,Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
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Tsuboyama M, Liu J, Kaye H, DiBacco M, Pearl PL, Rotenberg A. Transcranial Magnetic Stimulation in Succinic Semialdehyde Dehydrogenase Deficiency: A Measure of Maturational Trajectory of Cortical Excitability. J Child Neurol 2021; 36:1169-1176. [PMID: 34058900 PMCID: PMC8630082 DOI: 10.1177/08830738211008735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a disorder of GABA degradation with use-dependent downregulation of postsynaptic GABAA/B receptors. We aim to measure the resulting cortical excitation: inhibition ratio using transcranial magnetic stimulation. METHODS In this single-center observational study, 18 subjects with SSADHD and 8 healthy controls underwent transcranial magnetic stimulation. Resting motor threshold, cortical silent period, and long-interval intracortical inhibition were measured in both groups. Resting motor threshold in focal epilepsy patients from an institutional transcranial magnetic stimulation database were also included. RESULTS SSADHD subjects had higher resting motor threshold than healthy controls but lower relative to focal epilepsy patients. Resting motor threshold decreased with age in all groups. Cortical silent period was longer in SSADHD subjects than in healthy controls. No difference was detected in long-interval intracortical inhibition between the 2 groups. CONCLUSION Findings suggest abnormal corticospinal tract physiology in SSADHD, but with preserved developmental trajectory for corticospinal tract maturation. Defining features of these transcranial magnetic stimulation metrics in SSADHD will be better elucidated through this ongoing longitudinal study.
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Affiliation(s)
- Melissa Tsuboyama
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, 1862Boston Children's Hospital, Boston, MA, USA
| | - Jingjing Liu
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, 1862Boston Children's Hospital, Boston, MA, USA.,F.M. Kirby Neurobiology Center, 1862Boston Children's Hospital, Boston, MA, USA
| | - Harper Kaye
- 12259Boston University School of Medicine, Behavioral Neuroscience Program, Boston, MA, USA
| | - Melissa DiBacco
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, 1862Boston Children's Hospital, Boston, MA, USA
| | - Phillip L Pearl
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, 1862Boston Children's Hospital, Boston, MA, USA
| | - Alexander Rotenberg
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, 1862Boston Children's Hospital, Boston, MA, USA.,F.M. Kirby Neurobiology Center, 1862Boston Children's Hospital, Boston, MA, USA.,Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
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5
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Are there differences in cortical excitability between akinetic-rigid and tremor-dominant subtypes of Parkinson's disease? Neurophysiol Clin 2021; 51:443-453. [PMID: 34588134 DOI: 10.1016/j.neucli.2021.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE To assess by transcranial magnetic stimulation (TMS) the excitability of various cortical circuits in akinetic-rigid and tremor-dominant subtypes of Parkinson's disease (PD). METHODS The study included 92 patients with PD according to UK Brain Bank criteria, with akinetic-rigid (n = 64) or tremor-dominant (n = 28) subtype. Cortical excitability study, including resting and active motor thresholds (rMT and aMT), input-output curve of motor evoked potentials, contralateral and ipsilateral silent periods (cSP and iSP), short and long-interval intracortical inhibition (SICI and LICI), and intracortical facilitation (ICF) were measured. The results obtained were compared to a control group of 30 age- and sex-matched healthy subjects. RESULTS The patients in the tremor group had significantly lower rMT and aMT compared to controls and akinetic-rigid patients and significantly shorter iSP duration compared to akinetic-rigid patients, while iSP latency tended to be longer in akinetic-rigid patients compared to controls. There were no significant differences between the two PD subgroups regarding other cortical excitability parameters, including paired-pulse TMS parameters. CONCLUSIONS Only subtle differences of cortical excitability were found between patients with akinetic-rigid vs. tremor-dominant subtype of PD. SIGNIFICANCE The clinical heterogeneity of PD patients probably has an impact on cortical excitability measures, far beyond the akinetic-rigid versus tremor-dominant profile.
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Rurak BK, Rodrigues JP, Power BD, Drummond PD, Vallence AM. Test Re-test Reliability of Dual-site TMS Measures of SMA-M1 Connectivity Differs Across Inter-stimulus Intervals in Younger and Older Adults. Neuroscience 2021; 472:11-24. [PMID: 34333064 DOI: 10.1016/j.neuroscience.2021.07.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 12/24/2022]
Abstract
Dual-site transcranial magnetic stimulation (TMS) is a promising tool to measure supplementary motor area and primary motor cortex (SMA-M1) connectivity in younger and older adults, and could be used to understand the pathophysiology of movement disorders. However, test re-test reliability of dual-site TMS measures of SMA-M1 connectivity has not been established. We examined the reliability of SMA-M1 connectivity using dual-site TMS in two sessions in 30 younger and 30 older adults. For dual-site TMS, a conditioning pulse delivered to SMA (140% of active motor threshold) preceded a test pulse delivered to M1 (intensity that elicited MEPs of ~1 mV) by inter-stimulus intervals (ISI) of 6 ms, 7 ms, and 8 ms. Moderate intraclass correlation coefficients (ICC) were found for SMA-M1 connectivity at an ISI of 7 ms in younger (ICC: 0.69) and older adults (ICC: 0.68). Poor ICCs were found for SMA-M1 connectivity at ISIs of 6 ms and 8 ms in both age groups (ICC range: 0.01-0.40). We report evidence for stable measures of SMA-M1 connectivity at an ISI of 7 ms in both age groups. These findings are foundational for future research developing evidence-based interventions to strengthen SMA-M1 connectivity to improve bilateral motor control in older adults and populations with movement disorders.
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Affiliation(s)
- B K Rurak
- Discipline of Psychology, College of Science, Health, Engineering and Education, Murdoch University, Australia; Centre for Healthy Ageing, Health Futures Institute, Murdoch University, Murdoch 6150, Australia.
| | | | - B D Power
- Hollywood Private Hospital, Australia; School of Medicine Fremantle, University of Notre Dame, Australia
| | - P D Drummond
- Discipline of Psychology, College of Science, Health, Engineering and Education, Murdoch University, Australia; Centre for Healthy Ageing, Health Futures Institute, Murdoch University, Murdoch 6150, Australia
| | - A M Vallence
- Discipline of Psychology, College of Science, Health, Engineering and Education, Murdoch University, Australia; Centre for Healthy Ageing, Health Futures Institute, Murdoch University, Murdoch 6150, Australia; Centre for Molecular Medicine and Innovative Therapeutics, Murdoch 6150, Australia
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7
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Qasem H, Fujiyama H, Rurak BK, Vallence AM. Good test–retest reliability of a paired-pulse transcranial magnetic stimulation protocol to measure short-interval intracortical facilitation. Exp Brain Res 2020; 238:2711-2723. [DOI: 10.1007/s00221-020-05926-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/15/2020] [Indexed: 12/21/2022]
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8
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de Goede AA, Cumplido-Mayoral I, van Putten MJAM. Spatiotemporal Dynamics of Single and Paired Pulse TMS-EEG Responses. Brain Topogr 2020; 33:425-437. [PMID: 32367427 PMCID: PMC7293671 DOI: 10.1007/s10548-020-00773-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 04/21/2020] [Indexed: 12/28/2022]
Abstract
For physiological brain function a particular balance between excitation and inhibition is essential. Paired pulse transcranial magnetic stimulation (TMS) can estimate cortical excitability and the relative contribution of inhibitory and excitatory networks. Combining TMS with electroencephalography (EEG) enables additional assessment of the spatiotemporal dynamics of neuronal responses in the stimulated brain. This study aims to evaluate the spatiotemporal dynamics and stability of single and paired pulse TMS-EEG responses, and assess long intracortical inhibition (LICI) at the cortical level. Twenty-five healthy subjects were studied twice, approximately one week apart. Manual coil positioning was applied in sixteen subjects and robot-guided positioning in nine. Both motor cortices were stimulated with 50 single pulses and 50 paired pulses at each of the five interstimulus intervals (ISIs): 100, 150, 200, 250 and 300 ms. To assess stability and LICI, the intraclass correlation coefficient and cluster-based permutation analysis were used. We found great resemblance in the topographical distribution of the characteristic TMS-EEG components for single and paired pulse TMS. Stimulation of the dominant and non-dominant hemisphere resulted in a mirrored spatiotemporal dynamics. No significant effect on the TMS-EEG responses was found for either stimulated hemisphere, time or coil positioning method, indicating the stability of both single and paired pulse TMS-EEG responses. For all ISIs, LICI was characterized by significant suppression of the late N100 and P180 components in the central areas, without affecting the early P30, N45 and P60 components. These observations in healthy subjects can serve as reference values for future neuropsychiatric and pharmacological studies.
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Affiliation(s)
- Annika A de Goede
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente, P.O. Box 217, Technohal 3385, 7500 AE, Enschede, The Netherlands.
| | - Irene Cumplido-Mayoral
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente, P.O. Box 217, Technohal 3385, 7500 AE, Enschede, The Netherlands.,Biomedical Engineering, Technical Medical Centre, University of Twente, Enschede, The Netherlands
| | - Michel J A M van Putten
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente, P.O. Box 217, Technohal 3385, 7500 AE, Enschede, The Netherlands.,Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Enschede, The Netherlands
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9
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de Goede AA, van Putten MJAM. Infraslow activity as a potential modulator of corticomotor excitability. J Neurophysiol 2019; 122:325-335. [PMID: 31116669 DOI: 10.1152/jn.00663.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fluctuations in cortical excitability are a candidate mechanism involved in the trial-to-trial variation of motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS). We explore whether infraslow EEG activity (<0.1 Hz) modulates corticomotor excitability by evaluating the presence of temporal and phase clustering of TMS-induced MEPs. In addition, we evaluate the dependence of MEP amplitude on the phase of the infraslow activity. Twenty-three subjects were stimulated at an intensity above the resting motor threshold (rMT) and ten at the rMT. We evaluated whether temporal and phase clustering of MEP size and MEP generation were present, using 1,000 surrogates with a similar amplitude or occurrence distribution. To evaluate the MEP amplitude dependence, we used the least-square method to approximate the linear circular data by fitting a sine function. We observed significant temporal clustering at a group level, in all individual subjects stimulated at rMT and in the majority of those stimulated above rMT, suggesting underlying determinism of corticomotor excitability instead of randomly generated fluctuations. The majority of subjects showed significant phase clustering for MEP size and for MEP occurrence, and significant phase clustering was found at the group level. Furthermore, in approximately one-quarter to one-half of the subjects we found a significant correlation and dependence of MEP amplitude on the phase of infraslow activity, respectively. Although other mechanisms very likely contribute as well, our findings seem to suggest that infraslow activity is involved in the variability of cortical excitability and TMS-induced responses. NEW & NOTEWORTHY Cortical excitability measures are highly variable during transcranial magnetic stimulation. Although ongoing brain oscillations are assumed to modulate excitability, no consistent associations are found for the traditional frequency bands. We focus on the role of infraslow EEG activity, defined as rhythms with frequencies < 0.1 Hz. We provide experimental evidence suggesting that infraslow activity most likely modulates corticomotor excitability and that response variation could be reduced when stimulation is targeted at a specific infraslow phase.
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Affiliation(s)
- Annika A de Goede
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente , Enschede , The Netherlands
| | - Michel J A M van Putten
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente , Enschede , The Netherlands.,Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Enschede , The Netherlands
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10
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de Goede AA, Ter Braack EM, van Putten MJAM. Accurate Coil Positioning is Important for Single and Paired Pulse TMS on the Subject Level. Brain Topogr 2018; 31:917-930. [PMID: 29943242 PMCID: PMC6182440 DOI: 10.1007/s10548-018-0655-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 06/07/2018] [Indexed: 12/04/2022]
Abstract
Function-guided navigation is commonly used when assessing cortical excitability using transcranial magnetic stimulation (TMS). However, the required accuracy, stability and the effect of a change in coil positioning are not entirely known. This study investigates the accuracy of function-guided navigation for determining the hotspot. Furthermore, it evaluates the effect of a change in coil location on the single and paired pulse excitability measures: motor evoked potential (MEP) amplitude, TMS evoked potential (TEP) and long intracortical inhibition (LICI), and of a change in coil orientation on LICI. Eight healthy subjects participated in the single pulse study, and ten in the paired pulse study. A robot-guided navigation system was used to ensure accurate and stable coil positioning at the motor hotspot as determined using function-guided navigation. In addition, we targeted four locations at 2 mm and four at 5 mm distance around the initially defined hotspot, and we increased and decreased the coil orientation by 10°. In none of the subjects, the largest MEP amplitudes were evoked at the originally determined hotspot, resulting in a poor accuracy of function-guided navigation. At the group level, a change in coil location had no significant effect on the MEP amplitude, TEP, or LICI, and a change in coil orientation did not significantly affected LICI. However, at the subject level significant effects on MEP amplitude, TEP, and LICI were found for changes in coil location or orientation, although absolute differences were relatively small and did not show a consistent pattern. This study indicates that a high accuracy in coil positioning is especially required to measure cortical excitability reliably in individual subjects using single or paired pulse TMS.
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Affiliation(s)
- Annika A de Goede
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente, Carré 3.714, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
| | - Esther M Ter Braack
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente, Carré 3.714, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Michel J A M van Putten
- Department of Clinical Neurophysiology, Technical Medical Centre, University of Twente, Carré 3.714, P.O. Box 217, 7500 AE, Enschede, The Netherlands
- Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Enschede, The Netherlands
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11
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The minimal number of TMS trials required for the reliable assessment of corticospinal excitability, short interval intracortical inhibition, and intracortical facilitation. Neurosci Lett 2018; 674:94-100. [PMID: 29551425 DOI: 10.1016/j.neulet.2018.03.026] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/19/2018] [Accepted: 03/13/2018] [Indexed: 11/23/2022]
Abstract
Transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) are frequently used to assess corticospinal and intercortical activities. Trial to trial variance of the potentials is commonly observed, and averages of multiple MEPs are usually reported. Multiple trials have resources implications and are not compatible with some experimental protocols. This study investigated the minimum number of MEPs required to reliably assess corticospinal excitability (CSE), short interval intracortical inhibition (SICI) and intercortical facilitation (ICF), within and between sessions. Fifteen healthy volunteers received 35 single-pulse TMS for CSE assessments and 35 paired-pulse TMS for SICI and ICF measurements. Intra- and intersession reliability were examined using intra-class correlation coefficient tests, and stability of the measures was assessed using a general equation estimation analysis. Coefficients of variation were used to probe the effects of inter-individual variability on reliability results. All analyses were carried out on cumulative averages. The optimal number of trials to ensure "excellent" intra and inter-session reliability with low inter-individual variability and the highest level of stability was found to be 20 for CSE and 26 for SICI assessments. Although 30 consecutive trials produced highly reliable ICF measures within a session, inter-session reliability was not significant across 35 trials. These findings have significant implications for improving time efficiency of TMS experiments without compromising intra- or intersession reliability.
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12
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Bauer PR, de Goede AA, Stern WM, Pawley AD, Chowdhury FA, Helling RM, Bouet R, Kalitzin SN, Visser GH, Sisodiya SM, Rothwell JC, Richardson MP, van Putten MJAM, Sander JW. Long-interval intracortical inhibition as biomarker for epilepsy: a transcranial magnetic stimulation study. Brain 2018; 141:409-421. [PMID: 29340584 PMCID: PMC5837684 DOI: 10.1093/brain/awx343] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/08/2017] [Accepted: 10/24/2017] [Indexed: 11/13/2022] Open
Abstract
Cortical excitability, as measured by transcranial magnetic stimulation combined with electromyography, is a potential biomarker for the diagnosis and follow-up of epilepsy. We report on long-interval intracortical inhibition data measured in four different centres in healthy controls (n = 95), subjects with refractory genetic generalized epilepsy (n = 40) and with refractory focal epilepsy (n = 69). Long-interval intracortical inhibition was measured by applying two supra-threshold stimuli with an interstimulus interval of 50, 100, 150, 200 and 250 ms and calculating the ratio between the response to the second (test stimulus) and to the first (conditioning stimulus). In all subjects, the median response ratio showed inhibition at all interstimulus intervals. Using a mixed linear-effects model, we compared the long-interval intracortical inhibition response ratios between the different subject types. We conducted two analyses; one including data from the four centres and one excluding data from Centre 2, as the methods in this centre differed from the others. In the first analysis, we found no differences in long-interval intracortical inhibition between the different subject types. In all subjects, the response ratios at interstimulus intervals 100 and 150 ms showed significantly more inhibition than the response ratios at 50, 200 and 250 ms. Our second analysis showed a significant interaction between interstimulus interval and subject type (P = 0.0003). Post hoc testing showed significant differences between controls and refractory focal epilepsy at interstimulus intervals of 100 ms (P = 0.02) and 200 ms (P = 0.04). There were no significant differences between controls and refractory generalized epilepsy groups or between the refractory generalized and focal epilepsy groups. Our results do not support the body of previous work that suggests that long-interval intracortical inhibition is significantly reduced in refractory focal and genetic generalized epilepsy. Results from the second analysis are even in sharper contrast with previous work, showing inhibition in refractory focal epilepsy at 200 ms instead of facilitation previously reported. Methodological differences, especially shorter intervals between the pulse pairs, may have contributed to our inability to reproduce previous findings. Based on our results, we suggest that long-interval intracortical inhibition as measured by transcranial magnetic stimulation and electromyography is unlikely to have clinical use as a biomarker of epilepsy.
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Affiliation(s)
- Prisca R Bauer
- NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Stichting Epilepsie Instellingen Nederland (SEIN), Achterweg 5, 2103 SW Heemstede, The Netherlands
| | - Annika A de Goede
- Department of Clinical Neurophysiology, MIRA – Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - William M Stern
- NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Chalfont Centre for Epilepsy, Chalfont St Peter, SL9 0RJ, UK
| | - Adam D Pawley
- Institute of Psychiatry, Psychology and Neuroscience, King’s College London 16 De Crespigny Park, London, SE5 8AF, UK
| | - Fahmida A Chowdhury
- NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Institute of Psychiatry, Psychology and Neuroscience, King’s College London 16 De Crespigny Park, London, SE5 8AF, UK
| | - Robert M Helling
- Stichting Epilepsie Instellingen Nederland (SEIN), Achterweg 5, 2103 SW Heemstede, The Netherlands
- Image Sciences Institute, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Romain Bouet
- Lyon Neuroscience Research Center, INSERM U1028 - CNRS UMR5292, Université Claude Bernard Lyon1, Brain Dynamics and Cognition Team, Centre Hospitalier Le Vinatier (Bât. 452), 95 Bd Pinel, 69500 Bron, France
| | - Stiliyan N Kalitzin
- Stichting Epilepsie Instellingen Nederland (SEIN), Achterweg 5, 2103 SW Heemstede, The Netherlands
- Image Sciences Institute, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands
| | - Gerhard H Visser
- Stichting Epilepsie Instellingen Nederland (SEIN), Achterweg 5, 2103 SW Heemstede, The Netherlands
| | - Sanjay M Sisodiya
- NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Chalfont Centre for Epilepsy, Chalfont St Peter, SL9 0RJ, UK
| | - John C Rothwell
- NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Mark P Richardson
- Institute of Psychiatry, Psychology and Neuroscience, King’s College London 16 De Crespigny Park, London, SE5 8AF, UK
| | - Michel J A M van Putten
- Department of Clinical Neurophysiology, MIRA – Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Department of Clinical Neurophysiology and Neurology, Medisch Spectrum Twente, Koningsplein 1, 7512 KZ Enschede, The Netherlands
| | - Josemir W Sander
- NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Stichting Epilepsie Instellingen Nederland (SEIN), Achterweg 5, 2103 SW Heemstede, The Netherlands
- Chalfont Centre for Epilepsy, Chalfont St Peter, SL9 0RJ, UK
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