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McMackin R, Tadjine Y, Fasano A, Mitchell M, Heverin M, Awiszus F, Nasseroleslami B, Carson RG, Hardiman O. Examining short interval intracortical inhibition with different transcranial magnetic stimulation-induced current directions in ALS. Clin Neurophysiol Pract 2024; 9:120-129. [PMID: 38595691 PMCID: PMC11002888 DOI: 10.1016/j.cnp.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/21/2024] [Accepted: 03/03/2024] [Indexed: 04/11/2024] Open
Abstract
Objective To establish if induced current direction across the motor cortex alters the sensitivity of transcranial magnetic stimulation (TMS)-evoked short-interval intracortical inhibition (SICI) as an ALS biomarker. Methods Threshold tracking-TMS was undertaken in 35 people with ALS and 39 controls. Using a coil orientation which induces posterior-anterior (PA)-directed current across the motor cortex, SICI (1 ms and 3 ms interstimulus intervals) and intracortical facilitation (ICF, 10 ms interstimulus interval) were recorded. SICI3ms was also recorded using a coil orientation which induces anterior-posterior (AP)-directed current across the motor cortex. Results At group level, SICI3ms-PA (AUROC = 0.7), SICI3ms-AP (AUROC = 0.8) and SICI1ms (AUROC = 0.66) were substantially lower in those with ALS, although there was considerable interindividual heterogeneity. Averaging across interstimulus intervals (ISIs) marginally improved SICIPA sensitivity (AUROC = 0.76). Averaging SICI values across ISIs and orientations into a single SICI measure did not substantially improve sensitivity (AUROC = 0.81) compared to SICI3ms-AP alone. SICI3ms-AP and SICI3ms-PA did not significantly correlate (rho = 0.19, p = 0.313), while SICI1ms-PA and SICI3ms-PA did (rho = 0.37, p = 0.006). Further, those with ALS with the lowest SICI3ms-PA were not those with the lowest SICI3ms-AP. ICF was similar between groups (AUROC = 0.50). Conclusions SICIPA and SICIAP are uncorrelated measures of motor cortical inhibitory functions which are useful as distinct, unequally affected, measures of disinhibition in ALS. Significance Examining both SICIPA and SICIAP may facilitate more comprehensive characterisation of motor cortical disinhibition in ALS.
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Affiliation(s)
- Roisin McMackin
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Yasmine Tadjine
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Antonio Fasano
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Matthew Mitchell
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Mark Heverin
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Friedemann Awiszus
- Department of Orthopaedic Surgery, Otto-von-Guericke University, Magdeburg, Germany
| | - Bahman Nasseroleslami
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Richard G Carson
- Trinity College Institute of Neuroscience and School of Psychology, Trinity College Dublin, University of Dublin, Ireland
- School of Psychology, Queen's University Belfast
| | - Orla Hardiman
- Academic Unit of Neurology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Ireland
- Beaumont Hospital, Dublin, Ireland
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Desmons M, Theberge M, Mercier C, Massé-Alarie H. Contribution of neural circuits tested by transcranial magnetic stimulation in corticomotor control of low back muscle: a systematic review. Front Neurosci 2023; 17:1180816. [PMID: 37304019 PMCID: PMC10247989 DOI: 10.3389/fnins.2023.1180816] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 05/10/2023] [Indexed: 06/13/2023] Open
Abstract
Introduction Transcranial magnetic stimulation (TMS) is widely used to investigate central nervous system mechanisms underlying motor control. Despite thousands of TMS studies on neurophysiological underpinnings of corticomotor control, a large majority of studies have focused on distal muscles, and little is known about axial muscles (e.g., low back muscles). Yet, differences between corticomotor control of low back and distal muscles (e.g., gross vs. fine motor control) suggest differences in the neural circuits involved. This systematic review of the literature aims at detailing the organisation and neural circuitry underlying corticomotor control of low back muscles tested with TMS in healthy humans. Methods The literature search was performed in four databases (CINAHL, Embase, Medline (Ovid) and Web of science) up to May 2022. Included studies had to use TMS in combination with EMG recording of paraspinal muscles (between T12 and L5) in healthy participants. Weighted average was used to synthesise quantitative study results. Results Forty-four articles met the selection criteria. TMS studies of low back muscles provided consistent evidence of contralateral and ipsilateral motor evoked potentials (with longer ipsilateral latencies) as well as of short intracortical inhibition/facilitation. However, few or no studies using other paired pulse protocols were found (e.g., long intracortical inhibition, interhemispheric inhibition). In addition, no study explored the interaction between different cortical areas using dual TMS coil protocol (e.g., between primary motor cortex and supplementary motor area). Discussion Corticomotor control of low back muscles are distinct from hand muscles. Our main findings suggest: (i) bilateral projections from each single primary motor cortex, for which contralateral and ipsilateral tracts are probably of different nature (contra: monosynaptic; ipsi: oligo/polysynaptic) and (ii) the presence of intracortical inhibitory and excitatory circuits in M1 influencing the excitability of the contralateral corticospinal cells projecting to low back muscles. Understanding of these mechanisms are important for improving the understanding of neuromuscular function of low back muscles and to improve the management of clinical populations (e.g., low back pain, stroke).
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Affiliation(s)
- Mikaël Desmons
- Center for Interdisciplinary Research in Rehabilitation and Social Integration (Cirris), CIUSSS de la Capitale-Nationale, Quebec, QC, Canada
- Rehabilitation Department, Université Laval, Quebec, QC, Canada
| | - Michael Theberge
- Center for Interdisciplinary Research in Rehabilitation and Social Integration (Cirris), CIUSSS de la Capitale-Nationale, Quebec, QC, Canada
| | - Catherine Mercier
- Center for Interdisciplinary Research in Rehabilitation and Social Integration (Cirris), CIUSSS de la Capitale-Nationale, Quebec, QC, Canada
- Rehabilitation Department, Université Laval, Quebec, QC, Canada
| | - Hugo Massé-Alarie
- Center for Interdisciplinary Research in Rehabilitation and Social Integration (Cirris), CIUSSS de la Capitale-Nationale, Quebec, QC, Canada
- Rehabilitation Department, Université Laval, Quebec, QC, Canada
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Ma W, Nemdharry S, Elgueta Cancino E, Chiou SY. Influence of coil orientation on corticospinal excitability of trunk muscles during postural and volitional tasks in healthy adults. Front Hum Neurosci 2023; 17:1108169. [PMID: 36816500 PMCID: PMC9929149 DOI: 10.3389/fnhum.2023.1108169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
Introduction Trunk muscles play a role in maintaining postural stability and performing goal-directed voluntary movements in activities of daily living. Evidence has shown that the primary motor cortex (M1) is involved in modulation of postural control and voluntary movements of the trunk. However, it remains unknown whether the neural circuits within the M1 were recruited to the same extent between a postural task and a goal-directed voluntary task. Methods To address this, we examined latencies and amplitudes of motor evoked potentials (MEPs) of the erector spinae (ES) with transcranial magnetic stimulation (TMS) figure-of-eight coil oriented to induce latero-medial (LM), posterior-anterior (PA), and anterior-posterior (AP) currents in the M1 in twenty healthy participants during a dynamic shoulder flexion (DSF) task, a postural task requiring anticipatory postural adjustments (APAs), and during a static trunk extension (STE) task, a voluntary task without involvement of APAs. Results We found that differences in the AP-LM latency of ES MEP were longer compared with the PA-LM latency in both tasks. Corticospinal excitability was overall greater during the DSF task than during the STE task irrespective of the coil orientation. Discussion Our findings suggest that while the same neural circuits in the M1 were recruited to modulate both postural and voluntary control of the trunk, the contribution was greater to the postural task than the voluntary task, possibly due to the requirement of APAs in the task.
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Affiliation(s)
- Wesley Ma
- School of Sport, Exercise and Rehabilitation Science, University of Birmingham, Birmingham, United Kingdom
| | - Sheanil Nemdharry
- School of Sport, Exercise and Rehabilitation Science, University of Birmingham, Birmingham, United Kingdom
| | - Edith Elgueta Cancino
- School of Sport, Exercise and Rehabilitation Science, University of Birmingham, Birmingham, United Kingdom,Exercise and Rehabilitation Sciences Institute, School of Physical Therapy, Faculty of Rehabilitation Science, Universidad Andrés Bello, Santiago, Chile
| | - Shin-Yi Chiou
- School of Sport, Exercise and Rehabilitation Science, University of Birmingham, Birmingham, United Kingdom,*Correspondence: Shin-Yi Chiou ✉
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Neige C, Ciechelski V, Lebon F. The recruitment of indirect waves within primary motor cortex during motor imagery: A directional transcranial magnetic stimulation study. Eur J Neurosci 2022; 56:6187-6200. [PMID: 36215136 PMCID: PMC10092871 DOI: 10.1111/ejn.15843] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 09/15/2022] [Accepted: 09/28/2022] [Indexed: 12/29/2022]
Abstract
Motor imagery (MI) refers to the mental simulation of an action without overt movement. While numerous transcranial magnetic stimulation (TMS) studies provided evidence for a modulation of corticospinal excitability and intracortical inhibition during MI, the neural signature within the primary motor cortex is not clearly established. In the current study, we used directional TMS to probe the modulation of the excitability of early and late indirect waves (I-waves) generating pathways during MI. Corticospinal responses evoked by TMS with posterior-anterior (PA) and anterior-posterior (AP) current flow within the primary motor cortex evoke preferentially early and late I-waves, respectively. Seventeen participants were instructed to stay at rest or to imagine maximal isometric contractions of the right flexor carpi radialis. We demonstrated that the increase of corticospinal excitability during MI is greater with PA than AP orientation. By using paired-pulse stimulations, we confirmed that short-interval intracortical inhibition (SICI) increased during MI in comparison to rest with PA orientation, whereas we found that it decreased with AP orientation. Overall, these results indicate that the pathways recruited by PA and AP orientations that generate early and late I-waves are differentially modulated by MI.
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Affiliation(s)
- Cécilia Neige
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, Dijon, France.,Centre Hospitalier Le Vinatier, Université Claude Bernard Lyon 1, INSERM, CNRS, CRNL U1028 UMR5292, PsyR2 Team, Bron, France
| | - Valentin Ciechelski
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, Dijon, France
| | - Florent Lebon
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, Dijon, France
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5
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Sasaki R, Hand BJ, Semmler JG, Opie GM. Modulation of I-Wave Generating Pathways With Repetitive Paired-Pulse Transcranial Magnetic Stimulation: A Transcranial Magnetic Stimulation–Electroencephalography Study. Neuromodulation 2022:S1094-7159(22)01353-8. [DOI: 10.1016/j.neurom.2022.10.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/11/2022] [Accepted: 10/30/2022] [Indexed: 12/03/2022]
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6
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Mental practice modulates functional connectivity between the cerebellum and the primary motor cortex. iScience 2022; 25:104397. [PMID: 35637729 PMCID: PMC9142644 DOI: 10.1016/j.isci.2022.104397] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 03/21/2022] [Accepted: 05/09/2022] [Indexed: 01/07/2023] Open
Abstract
Our brain has the extraordinary capacity to improve motor skills through mental practice. Conceptually, this ability is attributed to internal forward models, which are cerebellar neural networks that can predict the sensory consequences of motor commands. In our study, we employed single and dual-coil transcranial magnetic stimulations to probe the level of corticospinal excitability and cerebellar-brain inhibition, respectively, before and after a mental practice session or a control session. Motor skill (i.e., accuracy and speed) was measured using a sequential finger tapping-task. We found that mental practice enhanced both speed and accuracy. In parallel, the functional connectivity between the cerebellum and the primary motor cortex changed, with less inhibition from the first to the second. These findings reveal the existence of neuroplastic changes within the cerebellum, supporting the involvement of internal models after mental practice. The update of internal forward models involves cerebellar neural adaptations Mental practice is assumed to engage internal forward models Cerebellar-brain Inhibition was probed by TMS before and after mental practice Mental practice reduces Cerebellar-brain Inhibition and may update internal models
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7
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Assessment of cortical inhibition depends on inter individual differences in the excitatory neural populations activated by transcranial magnetic stimulation. Sci Rep 2022; 12:9923. [PMID: 35705672 PMCID: PMC9200840 DOI: 10.1038/s41598-022-14271-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 06/03/2022] [Indexed: 11/28/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is used to probe inhibitory intracortical neurotransmission and has been used to infer the neurobiological dysfunction that may underly several neurological disorders. One technique, short-interval intracortical inhibition (SICI), indexes gamma-aminobutyric acid (GABA) mediated inhibitory activity and is a promising biomarker. However emerging evidence suggests SICI does not exclusively represent GABAergic activity because it may be influenced by inter-individual differences in the specific excitatory neural populations activated by TMS. Here we used the latency of TMS motor evoked potentials (MEPs) to index these inter-individual differences, and found that a significant proportion of the observed variability in SICI magnitude was accounted for by MEP latency, r = − 0.57, r2 = 0.33, p = .014. We conclude that SICI is influenced by inter-individual differences in the excitatory neural populations activated by TMS, reducing the precision of this GABAergic probe. Interpreting SICI measures in the context of MEP latency may facilitate a more precise assessment of GABAergic intracortical inhibition. The reduced cortical inhibition observed in some neuropathologies could be influenced by reduced activity in specific excitatory neural populations. Including MEP latency assessment in research investigating SICI in clinical groups could assist in differentiating the cortical circuits impacted by neurological disorders.
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8
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Sasaki R, Semmler JG, Opie GM. Threshold Tracked Short-Interval Intracortical Inhibition More Closely Predicts the Cortical Response to Transcranial Magnetic Stimulation. Neuromodulation 2022; 25:614-623. [DOI: 10.1016/j.neurom.2021.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 01/14/2023]
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9
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Intracortical facilitation and inhibition in human primary motor cortex during motor skill acquisition. Exp Brain Res 2022; 240:3289-3304. [PMID: 36308563 PMCID: PMC9678989 DOI: 10.1007/s00221-022-06496-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 10/20/2022] [Indexed: 01/15/2023]
Abstract
The primary motor cortex (M1) is critical for movement execution, but its role in motor skill acquisition remains elusive. Here, we examine the role of M1 intracortical circuits during skill acquisition. Paired-pulse transcranial magnetic stimulation (TMS) paradigms of short-interval intracortical facilitation (SICF) and inhibition (SICI) were used to assess excitatory and inhibitory circuits, respectively. We hypothesised that intracortical facilitation and inhibition circuits in M1 would be modulated to support acquisition of a novel visuomotor skill. Twenty-two young, neurologically healthy adults trained with their nondominant hand on a skilled and non-skilled sequential visuomotor isometric finger abduction task. Electromyographic recordings were obtained from the nondominant first dorsal interosseous (FDI) muscle. Corticomotor excitability, SICF, and SICI were examined before, at the midway point, and after the 10-block motor training. SICI was assessed using adaptive threshold-hunting procedures. Task performance improved after the skilled, but not non-skilled, task training, which likely reflected the increase in movement speed during training. The amplitudes of late SICF peaks were modulated with skilled task training. There was no modulation of the early SICF peak, SICI, and corticomotor excitability with either task training. There was also no association between skill acquisition and SICF or SICI. The findings indicate that excitatory circuitries responsible for the generation of late SICF peaks, but not the early SICF peak, are modulated in motor skill acquisition for a sequential visuomotor isometric finger abduction task.
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10
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Neva JL, Brown KE, Peters S, Feldman SJ, Mahendran N, Boisgontier MP, Boyd LA. Acute Exercise Modulates the Excitability of Specific Interneurons in Human Motor Cortex. Neuroscience 2021; 475:103-116. [PMID: 34487820 DOI: 10.1016/j.neuroscience.2021.08.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 10/20/2022]
Abstract
Acute exercise can modulate the excitability of the non-exercised upper-limb representation in the primary motor cortex (M1). Accumulating evidence demonstrates acute exercise affects measures of M1 intracortical excitability, with some studies also showing altered corticospinal excitability. However, the influence of distinct M1 interneuron populations on the modulation of intracortical and corticospinal excitability following acute exercise is currently unknown. We assessed the impact of an acute bout of leg cycling exercise on unique M1 interneuron excitability of a non-exercised intrinsic hand muscle using transcranial magnetic stimulation (TMS) in young adults. Specifically, posterior-to-anterior (PA) and anterior-to-posterior (AP) TMS current directions were used to measure the excitability of distinct populations of interneurons before and after an acute bout of exercise or rest. Motor evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) were measured in the PA and AP current directions in M1 at two time points separated by 25 min of rest, as well as immediately and 30 min after a 25-minute bout of moderate-intensity cycling exercise. Thirty minutes after exercise, MEP amplitudes were significantly larger than other timepoints when measured with AP current, whereas MEP amplitudes derived from PA current did not show this effect. Similarly, SICI was significantly decreased immediately following acute exercise measured with AP but not PA current. Our findings suggest that the excitability of unique M1 interneurons are differentially modulated by acute exercise. These results indicate that M1 interneurons preferentially activated by AP current may play an important role in the exercise-induced modulation of intracortical and corticospinal excitability.
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Affiliation(s)
- Jason L Neva
- Université de Montréal, École de kinésiologie et des sciences de l'activité physique, Faculté de médecine, Montréal, QC, Canada; Centre de recherche de l'institut universitaire de gériatrie de Montréal, Montréal, QC, Canada.
| | - Katlyn E Brown
- University of Waterloo, Department of Kinesiology, Applied Health Sciences, Waterloo, ON, Canada
| | - Sue Peters
- Rehabilitation Research Program, GF Strong Rehabilitation Centre, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; University of British Columbia, Department of Physical Therapy, Faculty of Medicine, Vancouver, BC, Canada
| | - Samantha J Feldman
- Graduate Program in Clinical Developmental Neuropsychology, Department of Psychology, York University, Toronto, ON, Canada
| | - Niruthikha Mahendran
- University of Queensland, Discipline of Physiotherapy, School of Health and Rehabilitation Sciences, Brisbane, Australia
| | - Matthieu P Boisgontier
- School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa, Ottawa ON, Canada; Bruyère Research Institute, Ottawa, ON, Canada
| | - Lara A Boyd
- University of British Columbia, Department of Physical Therapy, Faculty of Medicine, Vancouver, BC, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
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11
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Desmons M, Rohel A, Desgagnés A, Mercier C, Massé-Alarie H. Influence of different transcranial magnetic stimulation current directions on the corticomotor control of lumbar erector spinae muscles during a static task. J Neurophysiol 2021; 126:1276-1288. [PMID: 34550037 DOI: 10.1152/jn.00137.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Different directions of transcranial magnetic stimulation (TMS) can activate different neuronal circuits. Whereas posteroanterior current (PA-TMS) depolarizes mainly interneurons in primary motor cortex (M1), an anteroposterior current (AP-TMS) has been suggested to activate different M1 circuits and perhaps axons from the premotor regions. Although M1 is also involved in the control of axial muscles, no study has explored whether different current directions activate different M1 circuits that may have distinct functional roles. The aim of the study was to compare the effect of different current directions (PA- and AP-TMS) on the corticomotor control and spatial cortical organization of the lumbar erector spinae muscle (LES). Thirty-four healthy participants were recruited for two independent experiments, and LES motor-evoked potentials (MEPs) were recorded. In experiment 1 (n = 17), active motor threshold (AMT), MEP latencies, recruitment curve (90% to 160% AMT), and excitatory and inhibitory intracortical mechanisms by paired-pulse TMS (80% followed by 120% AMT stimuli at 2-, 3-, 10-, and 15-ms interstimulus intervals) were tested with a double-cone (n = 12) and a figure-of-eight (n = 5) coil. In experiment 2 (n = 17), LES cortical representations were tested with PA- and AP-TMS. AMT was higher for AP- compared with PA-TMS (P = 0.002). Longer latencies with AP-TMS were present compared with PA-TMS (P = 0.017). AP-TMS produced more inhibition compared with PA-TMS at 2 ms and 3 ms (P = 0.010), but no difference was observed for longer intervals. No difference was found for recruitment curve and mapping. These findings suggest that PA- and AP-TMS may activate different cortical circuits controlling low back muscles, as proposed for hand muscles.NEW & NOTEWORTHY For the first time, anteroposterior and posteroanterior induced electric currents in the brain were compared when targeting back muscle representation with transcranial magnetic stimulation. The use of the anteroposterior current resulted in later response latency, larger inhibition probed by paired-pulse stimulation, and higher motor threshold. These important differences between current directions suggest that each of the current directions may recruit specific cortical circuits involved in the control of back muscles, similar to that for hand muscles.
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Affiliation(s)
- Mikaël Desmons
- CIRRIS Research Centre, Université Laval, Quebec City, Quebec, Canada
| | - Antoine Rohel
- CIRRIS Research Centre, Université Laval, Quebec City, Quebec, Canada
| | - Amélie Desgagnés
- CIRRIS Research Centre, Université Laval, Quebec City, Quebec, Canada
| | - Catherine Mercier
- CIRRIS Research Centre, Université Laval, Quebec City, Quebec, Canada.,Rehabilitation Unit, Université Laval, Quebec City, Quebec, Canada
| | - Hugo Massé-Alarie
- CIRRIS Research Centre, Université Laval, Quebec City, Quebec, Canada.,Rehabilitation Unit, Université Laval, Quebec City, Quebec, Canada
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Tugin S, Souza VH, Nazarova MA, Novikov PA, Tervo AE, Nieminen JO, Lioumis P, Ziemann U, Nikulin VV, Ilmoniemi RJ. Effect of stimulus orientation and intensity on short-interval intracortical inhibition (SICI) and facilitation (SICF): A multi-channel transcranial magnetic stimulation study. PLoS One 2021; 16:e0257554. [PMID: 34550997 PMCID: PMC8457500 DOI: 10.1371/journal.pone.0257554] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/03/2021] [Indexed: 11/18/2022] Open
Abstract
Besides stimulus intensities and interstimulus intervals (ISI), the electric field (E-field) orientation is known to affect both short-interval intracortical inhibition (SICI) and facilitation (SICF) in paired-pulse transcranial magnetic stimulation (TMS). However, it has yet to be established how distinct orientations of the conditioning (CS) and test stimuli (TS) affect the SICI and SICF generation. With the use of a multi-channel TMS transducer that provides electronic control of the stimulus orientation and intensity, we aimed to investigate how changes in the CS and TS orientation affect the strength of SICI and SICF. We hypothesized that the CS orientation would play a major role for SICF than for SICI, whereas the CS intensity would be more critical for SICI than for SICF. In eight healthy subjects, we tested two ISIs (1.5 and 2.7 ms), two CS and TS orientations (anteromedial (AM) and posteromedial (PM)), and four CS intensities (50, 70, 90, and 110% of the resting motor threshold (RMT)). The TS intensity was fixed at 110% RMT. The intensities were adjusted to the corresponding RMT in the AM and PM orientations. SICI and SICF were observed in all tested CS and TS orientations. SICI depended on the CS intensity in a U-shaped manner in any combination of the CS and TS orientations. With 70% and 90% RMT CS intensities, stronger PM-oriented CS induced stronger inhibition than weaker AM-oriented CS. Similar SICF was observed for any CS orientation. Neither SICI nor SICF depended on the TS orientation. We demonstrated that SICI and SICF could be elicited by the CS perpendicular to the TS, which indicates that these stimuli affected either overlapping or strongly connected neuronal populations. We concluded that SICI is primarily sensitive to the CS intensity and that CS intensity adjustment resulted in similar SICF for different CS orientations.
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Affiliation(s)
- Sergei Tugin
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- BioMag Laboratory, University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Centre, Helsinki, Finland
- * E-mail:
| | - Victor H. Souza
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- BioMag Laboratory, University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Centre, Helsinki, Finland
- School of Physiotherapy, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil
| | - Maria A. Nazarova
- Centre for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of Economics, Moscow, Russia
- Federal State Budgetary Institution “Federal Center of Brain Research and Neurotechnologies” of the Federal Medical Biological Agency, Moscow, Russia
| | - Pavel A. Novikov
- Centre for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of Economics, Moscow, Russia
| | - Aino E. Tervo
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- BioMag Laboratory, University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Centre, Helsinki, Finland
| | - Jaakko O. Nieminen
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- BioMag Laboratory, University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Centre, Helsinki, Finland
| | - Pantelis Lioumis
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- BioMag Laboratory, University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Centre, Helsinki, Finland
| | - Ulf Ziemann
- Department of Neurology and Stroke, Eberhard Karls University, Tübingen, Germany
- Hertie Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany
| | - Vadim V. Nikulin
- Centre for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of Economics, Moscow, Russia
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Risto J. Ilmoniemi
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- BioMag Laboratory, University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Centre, Helsinki, Finland
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13
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Caux-Dedeystère A, Allart E, Morel P, Kreisler A, Derambure P, Devanne H. Late cortical disinhibition in focal hand dystonia. Eur J Neurosci 2021; 54:4712-4720. [PMID: 34061422 DOI: 10.1111/ejn.15333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 05/20/2021] [Accepted: 05/23/2021] [Indexed: 11/30/2022]
Abstract
In writer's cramp (WC), a form of focal hand dystonia, cortical GABAergic inhibitory mechanisms are altered and may cause involuntary tonic contractions while writing. The objective of this study was to explore the time course of long-interval intracortical inhibition (LICI) that involves gamma-amino butyric acid (GABA)-B transmission and late cortical disinhibition (LCD) (that combines GABA-A and GABA-B mechanisms) in patients with WC and in control subjects. A double pulse transcranial magnetic stimulation protocol was used to evoke LICI and LCD while the subjects either gripped a cylinder between their thumb and index fingers or relaxed all their upper limb muscles. We measured the ratio between primed and unprimed motor evoked potential in the first dorsal interosseous at interstimulus intervals ranging between 60 and 300 ms. Though the cortical silent period was not different between the groups, LICI lasted longer in patients with WC, that is, LCD was delayed for more than 30 ms and reached a higher level. In addition to the alteration of inhibitory mechanism mediated by GABA-B transmission, LCD which probably involves presynaptic inhibition is also modified in patients with WC with possible consequences on the activity of primary motor cortex inhibitory and excitatory circuits which control the hand muscles.caus.
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Affiliation(s)
- Alexandre Caux-Dedeystère
- ULR 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société, Univ Littoral Côte d'Opale, Univ Lille, Univ Artois, Calais, France
| | - Etienne Allart
- Rééducation Neurologique Cérébrolésion, CHU de Lille, Hôpital Pierre Swynghedauw, Lille, France.,univ Lille, UMR-S-1172 lilncog, Lille, France
| | - Pierre Morel
- ULR 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société, Univ Littoral Côte d'Opale, Univ Lille, Univ Artois, Calais, France
| | - Alexandre Kreisler
- Neurologie & Pathologie du Mouvement, CHU de Lille, Hôpital Roger Salengro, Lille, France
| | - Philippe Derambure
- univ Lille, UMR-S-1172 lilncog, Lille, France.,Neurophysiologie Clinique, CHU de Lille, Hôpital Roger Salengro, Lille, France
| | - Hervé Devanne
- ULR 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société, Univ Littoral Côte d'Opale, Univ Lille, Univ Artois, Calais, France.,Neurophysiologie Clinique, CHU de Lille, Hôpital Roger Salengro, Lille, France
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14
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Opie GM, Semmler JG. Preferential Activation of Unique Motor Cortical Networks With Transcranial Magnetic Stimulation: A Review of the Physiological, Functional, and Clinical Evidence. Neuromodulation 2020; 24:813-828. [PMID: 33295685 DOI: 10.1111/ner.13314] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/30/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022]
Abstract
OBJECTIVES The corticospinal volley produced by application of transcranial magnetic stimulation (TMS) over primary motor cortex consists of a number of waves generated by trans-synaptic input from interneuronal circuits. These indirect (I)-waves mediate the sensitivity of TMS to cortical plasticity and intracortical excitability and can be assessed by altering the direction of cortical current induced by TMS. While this methodological approach has been conventionally viewed as preferentially recruiting early or late I-wave inputs from a given populations of neurons, growing evidence suggests recruitment of different neuronal populations, and this would strongly influence interpretation and application of these measures. The aim of this review is therefore to consider the physiological, functional, and clinical evidence for the independence of the neuronal circuits activated by different current directions. MATERIALS AND METHODS To provide the relevant context, we begin with an overview of TMS methodology, focusing on the different techniques used to quantify I-waves. We then comprehensively review the literature that has used variations in coil orientation to investigate the I-wave circuits, grouping studies based on the neurophysiological, functional, and clinical relevance of their outcomes. RESULTS Review of the existing literature reveals significant evidence supporting the idea that varying current direction can recruit different neuronal populations having unique functionally and clinically relevant characteristics. CONCLUSIONS Further research providing greater characterization of the I-wave circuits activated with different current directions is required. This will facilitate the development of interventions that are able to modulate specific intracortical circuits, which will be an important application of TMS.
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Affiliation(s)
- George M Opie
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - John G Semmler
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
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15
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Tankisi H, Cengiz B, Howells J, Samusyte G, Koltzenburg M, Bostock H. Short-interval intracortical inhibition as a function of inter-stimulus interval: Three methods compared. Brain Stimul 2020; 14:22-32. [PMID: 33166726 DOI: 10.1016/j.brs.2020.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 10/28/2020] [Accepted: 11/01/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Short-interval intracortical inhibition (SICI), as measured by threshold-tracking as a function of inter-stimulus interval (ISI), has been proposed as a useful biomarker for amyotrophic lateral sclerosis (ALS), but its relationship to conventional amplitude measurements has not been established. METHODS Serial tracking of SICI at increasing ISIs from 1 to 7 ms (T-SICIs) was compared in 50 healthy control subjects with the same ISIs tracked in parallel (T-SICIp), and with conventional amplitude measurements (A-SICI). For T-SICIp and A-SICI, pairs of conditioning and test stimuli with different ISIs were pseudo-randomised and interspersed with test-alone stimuli given at regular intervals. Thresholds were estimated by regression of log peak-to-peak amplitude on stimulus. RESULTS T-SICIp and A-SICI were closely related: a ten-fold reduction in amplitude corresponding to an approximately 18% increase in threshold. Threshold increases were greater for T-SICIs than for T-SICIp at 3.5-5 ms (P < 0.001). This divergence depended on the initial settings and whether ISIs were progressively increased or decreased, and was attributed to the limitations of the serial tracking protocol. SICI variability between subjects was greatest for T-SICIs estimates and least for A-SICI, and only A-SICI estimates revealed a significant decline in inhibition with age. CONCLUSIONS The serial tracking protocol did not accurately show the dependence of inhibition on ISI. Randomising ISIs gives corresponding SICI measures, whether tracking thresholds or measuring amplitude measurements. SICI variability suggested that A-SICI measurements may be the most sensitive to loss of inhibition.
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Affiliation(s)
- Hatice Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | - Bülent Cengiz
- Department of Neurology, Gazi University Faculty of Medicine, Beşevler, 06500, Ankara, Turkey
| | - James Howells
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Gintaute Samusyte
- Department of Neurology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Martin Koltzenburg
- Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom; Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, WC1N 3BG, London, United Kingdom
| | - Hugh Bostock
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom.
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16
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Calvert GHM, McMackin R, Carson RG. Probing interhemispheric dorsal premotor-primary motor cortex interactions with threshold hunting transcranial magnetic stimulation. Clin Neurophysiol 2020; 131:2551-2560. [PMID: 32927210 DOI: 10.1016/j.clinph.2020.07.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 07/06/2020] [Accepted: 07/14/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To characterise the effect of altering transcranial magnetic stimulation parameters on the magnitude of interhemispheric inhibition (IHI) from dorsal premotor (PMd) to primary motor cortex (M1). METHOD We used a fully automated adaptive threshold hunting paradigm to quantify PMd-M1 IHI across a range of conditioning stimulus (CS) intensities (90%, 110%, 130% of resting motor threshold, rMT) and interstimulus intervals (ISIs) (8, 10, 40 ms). M1-M1 IHI was examined with CS intensities of 110%, 120%, and 130% rMT and ISIs of 10 and 40 ms. Two test coil orientations (inducing posterior-anterior or anterior-posterior current) were used. RESULTS PMd-M1 IHI was obtained consistently with posterior-anterior (but not anterior-posterior) test stimuli and increased with CS intensity. M1-M1 IHI was expressed across all conditions and increased with CS intensity when posterior-anterior but not anterior-posterior induced current was used. CONCLUSIONS The expression of PMd-M1 IHI is contingent on test coil orientation (requiring posterior-anterior induced current) and increases as a function of CS intensity. The expression of M1-M1 IHI is not dependent on test coil orientation. SIGNIFICANCE We defined a range of parameters that elicit reliable PMd-M1 IHI. This (threshold hunting) methodology may provide a means to quantify premotor-motor pathology and reveal novel quantitative biomarkers.
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Affiliation(s)
- Glenn H M Calvert
- Trinity College Institute of Neuroscience and School of Psychology, Lloyd Building, Trinity College Dublin, Dublin 2, Ireland; School of Psychology, Queen's University Belfast, David Keir Building, 18-30 Malone Road, Belfast BT9 5BN, Northern Ireland, UK
| | - Roisin McMackin
- Academic Unit of Neurology, 152-160 Pearse St., Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Richard G Carson
- Trinity College Institute of Neuroscience and School of Psychology, Lloyd Building, Trinity College Dublin, Dublin 2, Ireland; School of Psychology, Queen's University Belfast, David Keir Building, 18-30 Malone Road, Belfast BT9 5BN, Northern Ireland, UK.
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17
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Spampinato D. Dissecting two distinct interneuronal networks in M1 with transcranial magnetic stimulation. Exp Brain Res 2020; 238:1693-1700. [PMID: 32661650 PMCID: PMC7413864 DOI: 10.1007/s00221-020-05875-y] [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: 01/20/2020] [Accepted: 07/06/2020] [Indexed: 11/27/2022]
Abstract
Interactions from both inhibitory and excitatory interneurons are necessary components of cortical processing that contribute to the vast amount of motor actions executed by humans daily. As transcranial magnetic stimulation (TMS) over primary motor cortex is capable of activating corticospinal neurons trans-synaptically, studies over the past 30 years have provided how subtle changes in stimulation parameters (i.e., current direction, pulse width, and paired-pulse) can elucidate evidence for two distinct neuronal networks that can be probed with this technique. This article provides a brief review of some fundamental studies demonstrating how these networks have separable excitatory inputs to corticospinal neurons. Furthermore, the findings of recent investigations will be discussed in detail, illustrating how each network's sensitivity to different brain states (i.e., rest, movement preparation, and motor learning) is dissociable. Understanding the physiological characteristics of each network can help to explain why interindividual responses to TMS exist, while also providing insights into the role of these networks in various human motor behaviors.
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Affiliation(s)
- Danny Spampinato
- Department for Clinical and Movement Neurosciences, Institute of Neurology, University College of London, London, UK.
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18
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Neige C, Grosprêtre S, Martin A, Lebon F. Influence of Voluntary Contraction Level, Test Stimulus Intensity and Normalization Procedures on the Evaluation of Short-Interval Intracortical Inhibition. Brain Sci 2020; 10:brainsci10070433. [PMID: 32650395 PMCID: PMC7407177 DOI: 10.3390/brainsci10070433] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 12/13/2022] Open
Abstract
Short-interval intracortical inhibition (SICI) represents an inhibitory phenomenon acting at the cortical level. However, SICI estimation is based on the amplitude of a motor-evoked potential (MEP), which depends on the discharge of spinal motoneurones and the generation of compound muscle action potential (M-wave). In this study, we underpin the importance of taking into account the proportion of spinal motoneurones that are activated or not when investigating the SICI of the right flexor carpi radialis (normalization with maximal M-wave (Mmax) and MEPtest, respectively), in 15 healthy subjects. We probed SICI changes according to various MEPtest amplitudes that were modulated actively (four levels of muscle contraction: rest, 10%, 20% and 30% of maximal voluntary contraction (MVC)) and passively (two intensities of test transcranial magnetic stimulation (TMS): 120 and 130% of motor thresholds). When normalized to MEPtest, SICI remained unchanged by stimulation intensity and only decreased at 30% of MVC when compared with rest. However, when normalized to Mmax, we provided the first evidence of a strong individual relationship between SICI and MEPtest, which was ultimately independent from experimental conditions (muscle states and TMS intensities). Under similar experimental conditions, it is thus possible to predict SICI individually from a specific level of corticospinal excitability in healthy subjects.
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Affiliation(s)
- Cécilia Neige
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, F-21078 Dijon, France; (A.M.); (F.L.)
- Correspondence: ; Tel.: +33-3-8039-6761
| | - Sidney Grosprêtre
- EA4660-C3S Laboratory—Culture, Sport, Health and Society, Université Bourgogne Franche-Comté, 25000 Besançon, France;
| | - Alain Martin
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, F-21078 Dijon, France; (A.M.); (F.L.)
| | - Florent Lebon
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, F-21078 Dijon, France; (A.M.); (F.L.)
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19
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Advanced TMS approaches to probe corticospinal excitability during action preparation. Neuroimage 2020; 213:116746. [DOI: 10.1016/j.neuroimage.2020.116746] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/02/2020] [Accepted: 03/13/2020] [Indexed: 12/13/2022] Open
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20
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Unravelling the Modulation of Intracortical Inhibition During Motor Imagery: An Adaptive Threshold-Hunting Study. Neuroscience 2020; 434:102-110. [DOI: 10.1016/j.neuroscience.2020.03.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 03/22/2020] [Accepted: 03/23/2020] [Indexed: 12/13/2022]
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21
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Primary motor cortex function and motor skill acquisition: insights from threshold-hunting TMS. Exp Brain Res 2020; 238:1745-1757. [DOI: 10.1007/s00221-020-05791-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/18/2020] [Indexed: 12/11/2022]
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22
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Cirillo J, Mooney RA, Ackerley SJ, Barber PA, Borges VM, Clarkson AN, Mangold C, Ren A, Smith MC, Stinear CM, Byblow WD. Neurochemical balance and inhibition at the subacute stage after stroke. J Neurophysiol 2020; 123:1775-1790. [PMID: 32186435 DOI: 10.1152/jn.00561.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Stroke is a leading cause of death and disability worldwide with many people left with impaired motor function. Evidence from experimental animal models of stroke indicates that reducing motor cortex inhibition may facilitate neural plasticity and motor recovery. This study compared primary motor cortex (M1) inhibition measures over the first 12 wk after stroke with a cohort of age-similar healthy controls. The excitation-inhibition ratio and gamma-aminobutyric acid (GABA) neurotransmission within M1 were assessed using magnetic resonance spectroscopy and threshold hunting paired-pulse transcranial magnetic stimulation respectively. Upper limb impairment and function were assessed with the Fugl-Meyer Upper Extremity Scale and Action Research Arm Test. Patients with a functional corticospinal pathway had motor-evoked potentials on the paretic side and exhibited better recovery from upper limb impairment and recovery of function than patients without a functional corticospinal pathway. Compared with age-similar controls, the neurochemical balance in terms of the excitation-inhibition ratio was greater within contralesional M1 in patients with a functional corticospinal pathway. There was evidence for elevated long-interval inhibition in both ipsilesional and contralesional M1 compared with controls. Short-interval inhibition measures differed between the first and second phases, with evidence for elevation of the former only in ipsilesional M1 and no evidence of disinhibition for the latter. Overall, findings from transcranial magnetic stimulation indicate an upregulation of GABA-mediated tonic inhibition in M1 early after stroke. Therapeutic approaches that aim to normalize inhibitory tone during the subacute period warrant further investigation.NEW & NOTEWORTHY Magnetic resonance spectroscopy indicated higher excitation-inhibition ratios within motor cortex during subacute recovery than age-similar healthy controls. Measures obtained from adaptive threshold hunting paired-pulse transcranial magnetic stimulation indicated greater tonic inhibition in patients compared with controls. Therapeutic approaches that aim to normalize motor cortex inhibition during the subacute stage of recovery should be explored.
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Affiliation(s)
- John Cirillo
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Ronan A Mooney
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Suzanne J Ackerley
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Medicine, University of Auckland, Auckland, New Zealand
| | - P Alan Barber
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Victor M Borges
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | | | - Christine Mangold
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - April Ren
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
| | - Marie-Claire Smith
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Cathy M Stinear
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Winston D Byblow
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
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23
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Mooney RA, Ackerley SJ, Rajeswaran DK, Cirillo J, Barber PA, Stinear CM, Byblow WD. The Influence of Primary Motor Cortex Inhibition on Upper Limb Impairment and Function in Chronic Stroke: A Multimodal Study. Neurorehabil Neural Repair 2019; 33:130-140. [PMID: 30744527 DOI: 10.1177/1545968319826052] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Stroke is a leading cause of adult disability owing largely to motor impairment and loss of function. After stroke, there may be abnormalities in γ-aminobutyric acid (GABA)-mediated inhibitory function within primary motor cortex (M1), which may have implications for residual motor impairment and the potential for functional improvements at the chronic stage. OBJECTIVE To quantify GABA neurotransmission and concentration within ipsilesional and contralesional M1 and determine if they relate to upper limb impairment and function at the chronic stage of stroke. METHODS Twelve chronic stroke patients and 16 age-similar controls were recruited for the study. Upper limb impairment and function were assessed with the Fugl-Meyer Upper Extremity Scale and Action Research Arm Test. Threshold tracking paired-pulse transcranial magnetic stimulation protocols were used to examine short- and long-interval intracortical inhibition and late cortical disinhibition. Magnetic resonance spectroscopy was used to evaluate GABA concentration. RESULTS Short-interval intracortical inhibition was similar between patients and controls ( P = .10). Long-interval intracortical inhibition was greater in ipsilesional M1 compared with controls ( P < .001). Patients who did not exhibit late cortical disinhibition in ipsilesional M1 were those with greater upper limb impairment and worse function ( P = .002 and P = .017). GABA concentration was lower within ipsilesional ( P = .009) and contralesional ( P = .021) M1 compared with controls, resulting in an elevated excitation-inhibition ratio for patients. CONCLUSION These findings indicate that ipsilesional and contralesional M1 GABAergic inhibition are altered in this small cohort of chronic stroke patients. Further study is warranted to determine how M1 inhibitory networks might be targeted to improve motor function.
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Affiliation(s)
| | | | | | - John Cirillo
- 1 The University of Auckland, Auckland, New Zealand
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24
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Mooney RA, Cirillo J, Byblow WD. Neurophysiological mechanisms underlying motor skill learning in young and older adults. Exp Brain Res 2019; 237:2331-2344. [DOI: 10.1007/s00221-019-05599-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/04/2019] [Indexed: 01/03/2023]
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25
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Conventional or threshold-hunting TMS? A tale of two SICIs. Brain Stimul 2018; 11:1296-1305. [DOI: 10.1016/j.brs.2018.07.047] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 07/11/2018] [Accepted: 07/15/2018] [Indexed: 12/14/2022] Open
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26
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Mooney RA, Cirillo J, Byblow WD. Adaptive threshold hunting reveals differences in interhemispheric inhibition between young and older adults. Eur J Neurosci 2018; 48:2247-2258. [DOI: 10.1111/ejn.14097] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/26/2018] [Accepted: 07/31/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Ronan A. Mooney
- Department of Exercise Sciences; Movement Neuroscience Laboratory; The University of Auckland; Auckland New Zealand
- Centre for Brain Research; The University of Auckland; Auckland New Zealand
| | - John Cirillo
- Department of Exercise Sciences; Movement Neuroscience Laboratory; The University of Auckland; Auckland New Zealand
- Centre for Brain Research; The University of Auckland; Auckland New Zealand
| | - Winston D. Byblow
- Department of Exercise Sciences; Movement Neuroscience Laboratory; The University of Auckland; Auckland New Zealand
- Centre for Brain Research; The University of Auckland; Auckland New Zealand
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27
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Opie GM, Cirillo J, Semmler JG. Age-related changes in late I-waves influence motor cortex plasticity induction in older adults. J Physiol 2018; 596:2597-2609. [PMID: 29667190 DOI: 10.1113/jp274641] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 04/16/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The response to neuroplasticity interventions using transcranial magnetic stimulation (TMS) is reduced in older adults, which may be due, in part, to age-related alterations in interneuronal (I-wave) circuitry. The current study investigated age-related changes in interneuronal characteristics and whether they influence motor cortical plasticity in older adults. While I-wave recruitment was unaffected by age, there was a shift in the temporal characteristics of the late, but not the early I-waves. Using I-wave periodicity repetitive TMS (iTMS), we showed that these differences in I-wave characteristics influence the induction of cortical plasticity in older adults. ABSTRACT Previous research shows that neuroplasticity assessed using transcranial magnetic stimulation (TMS) is reduced in older adults. While this deficit is often assumed to represent altered synaptic modification processes, age-related changes in the interneuronal circuits activated by TMS may also contribute. Here we assessed age-related differences in the characteristics of the corticospinal indirect (I) waves and how they influence plasticity induction in primary motor cortex. Twenty young (23.7 ± 3.4 years) and 19 older adults (70.6 ± 6.0 years) participated in these studies. I-wave recruitment was assessed by changing the direction of the current used to activate the motor cortex, whereas short-interval intracortical facilitation (SICF) was recorded to assess facilitatory I-wave interactions. In a separate study, I-wave periodicity TMS (iTMS) was used to examine the effect of I-wave latency on motor cortex plasticity. Data from the motor-evoked potential (MEP) onset latency produced using different coil orientations suggested that there were no age-related differences in preferential I-wave recruitment (P = 0.6). However, older adults demonstrated significant reductions in MEP facilitation at all 3 SICF peaks (all P values < 0.05) and a delayed latency of the second and third SICF peaks (all P values < 0.05). Using I-wave intervals that were optimal for young and older adults, these changes in the late I-waves were shown to influence the plasticity response in older adults after iTMS. These findings suggest that temporal characteristics are delayed for the late I-waves in older adults, and that optimising TMS interventions based on I-wave characteristics may improve the plasticity response in older adults.
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Affiliation(s)
- George M Opie
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - John Cirillo
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, Auckland, New Zealand.,Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - John G Semmler
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
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28
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Mooney RA, Cirillo J, Byblow WD. Adaptive threshold hunting for the effects of transcranial direct current stimulation on primary motor cortex inhibition. Exp Brain Res 2018; 236:1651-1663. [DOI: 10.1007/s00221-018-5250-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 03/30/2018] [Indexed: 11/25/2022]
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29
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Samusyte G, Bostock H, Rothwell J, Koltzenburg M. Short-interval intracortical inhibition: Comparison between conventional and threshold-tracking techniques. Brain Stimul 2018; 11:806-817. [PMID: 29573989 PMCID: PMC6028741 DOI: 10.1016/j.brs.2018.03.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 02/28/2018] [Accepted: 03/03/2018] [Indexed: 12/13/2022] Open
Abstract
Background Short-interval intracortical inhibition (SICI) is conventionally measured as the relative amplitude reduction of motor evoked potentials (MEPs) by subthreshold conditioning stimuli. In threshold-tracking SICI (T-SICI), stimulus intensity is instead adjusted repeatedly to maintain a constant MEP and inhibition is measured as the relative threshold increase. T-SICI is emerging as a useful diagnostic test, but its relationship to conventional amplitude SICI (A-SICI) is unclear. Objective To compare T-SICI and its reliability with conventional A-SICI measurements. Methods In twelve healthy volunteers (6 men, median age 30 years), conventional and T-SICI were recorded at conditioning stimuli (CS) of 50–80% resting motor threshold (RMT) and interstimulus interval of 2.5 ms. Measurements were repeated on the same day and at least a week later by a single operator. Results Across the CS range, mean group T-SICI showed a strong linear relationship to the mean group values measured by conventional technique (y = 29.7–0.3x, R2 = 0.99), but there was considerable interindividual variability. At CS 60–80% RMT, T-SICI had excellent intraday (intraclass correlation coefficient, ICC, 0.81–0.92) and adequate-to-excellent interday (ICC 0.61–0.88) reproducibility. Conventional SICI took longer to complete (median of 5.8 vs 3.8 min, p < 0.001) and tended to have poorer reproducibility (ICC 0.17–0.42 intraday, 0.37–0.51 interday). With T-SICI, smaller sample sizes were calculated for equally powered interventional studies. Conclusion The close relationship between conventional and T-SICI suggests that both techniques reflect similar cortical inhibitory mechanisms. Threshold-tracking measurements of SICI may be able to improve reproducibility, to shorten acquisition time and to reduce sample sizes for interventional studies compared with the conventional technique. Threshold-tracking SICI correlates well with conventional measures. It shows a trend towards better reproducibility on a group level. Threshold-tracking SICI is potentially quicker to obtain. It may require a smaller sample size in interventional studies.
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Affiliation(s)
- Gintaute Samusyte
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom; Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, Queen Square, WC1N 3BG, London, United Kingdom.
| | - Hugh Bostock
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom.
| | - John Rothwell
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom.
| | - Martin Koltzenburg
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom; Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, Queen Square, WC1N 3BG, London, United Kingdom.
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Cirillo J, Cowie MJ, MacDonald HJ, Byblow WD. Response inhibition activates distinct motor cortical inhibitory processes. J Neurophysiol 2018; 119:877-886. [DOI: 10.1152/jn.00784.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We routinely cancel preplanned movements that are no longer required. If stopping is forewarned, proactive processes are engaged to selectively decrease motor cortex excitability. However, without advance information there is a nonselective reduction in motor cortical excitability. In this study we examined modulation of human primary motor cortex inhibitory networks during response inhibition tasks with informative and uninformative cues using paired-pulse transcranial magnetic stimulation. Long- (LICI) and short-interval intracortical inhibition (SICI), indicative of GABAB- and GABAA-receptor mediated inhibition, respectively, were examined from motor evoked potentials obtained in task-relevant and task-irrelevant hand muscles when response inhibition was preceded by informative and uninformative cues. When the participants (10 men and 8 women) were cued to stop only a subcomponent of the bimanual response, the remaining response was delayed, and the extent of delay was greatest in the more reactive context, when cues were uninformative. For LICI, inhibition was reduced in both muscles during all types of response inhibition trials compared with the pre-task resting baseline. When cues were uninformative and left-hand responses were suddenly canceled, task-relevant LICI positively correlated with response times of the responding right hand. In trials where left-hand responding was highly probable or known (informative cues), task-relevant SICI was reduced compared with that when cued to rest, revealing a motor set indicative of responding. These novel findings indicate that the GABAB-receptor-mediated pathway may set a default inhibitory tone according to task context, whereas the GABAA-receptor-mediated pathways are recruited proactively with response certainty. NEW & NOTEWORTHY We examined how informative and uninformative cues that trigger both proactive and reactive processes modulate GABAergic inhibitory networks within human primary motor cortex. We show that GABAB inhibition was released during the task regardless of cue type, whereas GABAA inhibition was reduced when responding was highly probable or known compared with rest. GABAB-receptor-mediated inhibition may set a default inhibitory tone, whereas GABAA circuits may be modulated proactively according to response certainty.
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Affiliation(s)
- John Cirillo
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - Matthew J. Cowie
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - Hayley J. MacDonald
- Sport, Exercise and Rehabilitation Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Winston D. Byblow
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, The University of Auckland, Auckland, New Zealand
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Mooney RA, Cirillo J, Byblow WD. GABA and primary motor cortex inhibition in young and older adults: a multimodal reliability study. J Neurophysiol 2017; 118:425-433. [PMID: 28424294 DOI: 10.1152/jn.00199.2017] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/19/2017] [Accepted: 04/19/2017] [Indexed: 12/14/2022] Open
Abstract
The effects of healthy aging on γ-aminobutyric acid (GABA) within primary motor cortex (M1) remain poorly understood. Studies have reported contrasting results, potentially due to limitations with the common assessment technique. The aim of the present study was to investigate the effect of healthy aging on M1 GABA concentration and neurotransmission using a multimodal approach. Fifteen young and sixteen older adults participated in this study. Magnetic resonance spectroscopy (MRS) was used to measure M1 GABA concentration. Single-pulse and threshold-tracking paired-pulse transcranial magnetic stimulation (TMS) protocols were used to examine cortical silent period duration, short- and long-interval intracortical inhibition (SICI and LICI), and late cortical disinhibition (LCD). The reliability of TMS measures was examined with intraclass correlation coefficient analyses. SICI at 1 ms was reduced in older adults (15.13 ± 2.59%) compared with young (25.66 ± 1.44%; P = 0.002). However, there was no age-related effect for cortical silent period duration, SICI at 3 ms, LICI, or LCD (all P > 0.66). The intersession reliability of threshold-tracking measures was good to excellent for both young (range 0.75-0.96) and older adults (range 0.88-0.93). Our findings indicate that extrasynaptic inhibition may be reduced with advancing age, whereas GABA concentration and synaptic inhibition are maintained. Furthermore, MRS and threshold-tracking TMS provide valid and reliable assessment of M1 GABA concentration and neurotransmission, respectively, in young and older adults.NEW & NOTEWORTHY γ-Aminobutyric acid (GABA) in primary motor cortex was assessed in young and older adults using magnetic resonance spectroscopy and threshold-tracking paired-pulse transcranial magnetic stimulation. Older adults exhibited reduced extrasynaptic inhibition (short-interval intracortical inhibition at 1 ms) compared with young, whereas GABA concentration and synaptic inhibition were similar between age groups. We demonstrate that magnetic resonance spectroscopy and threshold-tracking provide valid and reliable assessments of primary motor cortex GABA concentration and neurotransmission, respectively.
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Affiliation(s)
- Ronan A Mooney
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, New Zealand; and.,Centre for Brain Research, The University of Auckland, New Zealand
| | - John Cirillo
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, New Zealand; and.,Centre for Brain Research, The University of Auckland, New Zealand
| | - Winston D Byblow
- Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, New Zealand; and .,Centre for Brain Research, The University of Auckland, New Zealand
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