1
|
Haggie L, Besier T, McMorland A. Circuits in the motor cortex explain oscillatory responses to transcranial magnetic stimulation. Netw Neurosci 2024; 8:96-118. [PMID: 38562291 PMCID: PMC10861165 DOI: 10.1162/netn_a_00341] [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: 07/05/2023] [Accepted: 10/11/2023] [Indexed: 04/04/2024] Open
Abstract
Transcranial magnetic stimulation (TMS) is a popular method used to investigate brain function. Stimulation over the motor cortex evokes muscle contractions known as motor evoked potentials (MEPs) and also high-frequency volleys of electrical activity measured in the cervical spinal cord. The physiological mechanisms of these experimentally derived responses remain unclear, but it is thought that the connections between circuits of excitatory and inhibitory neurons play a vital role. Using a spiking neural network model of the motor cortex, we explained the generation of waves of activity, so called 'I-waves', following cortical stimulation. The model reproduces a number of experimentally known responses including direction of TMS, increased inhibition, and changes in strength. Using populations of thousands of neurons in a model of cortical circuitry we showed that the cortex generated transient oscillatory responses without any tuning, and that neuron parameters such as refractory period and delays influenced the pattern and timing of those oscillations. By comparing our network with simpler, previously proposed circuits, we explored the contributions of specific connections and found that recurrent inhibitory connections are vital in producing later waves that significantly impact the production of motor evoked potentials in downstream muscles (Thickbroom, 2011). This model builds on previous work to increase our understanding of how complex circuitry of the cortex is involved in the generation of I-waves.
Collapse
Affiliation(s)
- Lysea Haggie
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Thor Besier
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Angus McMorland
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
| |
Collapse
|
2
|
Guidali G, Zazio A, Lucarelli D, Marcantoni E, Stango A, Barchiesi G, Bortoletto M. Effects of transcranial magnetic stimulation (TMS) current direction and pulse waveform on cortico-cortical connectivity: A registered report TMS-EEG study. Eur J Neurosci 2023; 58:3785-3809. [PMID: 37649453 DOI: 10.1111/ejn.16127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/14/2023] [Accepted: 08/04/2023] [Indexed: 09/01/2023]
Abstract
Transcranial magnetic stimulation (TMS)-evoked potentials (TEPs) are a promising proxy for measuring effective connectivity, that is, the directed transmission of physiological signals along cortico-cortical tracts, and for developing connectivity-based biomarkers. A crucial point is how stimulation parameters may affect TEPs, as they may contribute to the general variability of findings across studies. Here, we manipulated two TMS parameters (i.e. current direction and pulse waveform) while measuring (a) an early TEP component reflecting contralateral inhibition of motor areas, namely, M1-P15, as an operative model of interhemispheric cortico-cortical connectivity, and (b) motor-evoked potentials (MEP) for the corticospinal pathway. Our results showed that these two TMS parameters are crucial to evoke the M1-P15, influencing its amplitude, latency, and replicability. Specifically, (a) M1-P15 amplitude was strongly affected by current direction in monophasic stimulation; (b) M1-P15 latency was significantly modulated by current direction for monophasic and biphasic pulses. The replicability of M1-P15 was substantial for the same stimulation condition. At the same time, it was poor when stimulation parameters were changed, suggesting that these factors must be controlled to obtain stable single-subject measures. Finally, MEP latency was modulated by current direction, whereas non-statistically significant changes were evident for amplitude. Overall, our study highlights the importance of TMS parameters for early TEP responses recording and suggests controlling their impact in developing connectivity biomarkers from TEPs. Moreover, these results point out that the excitability of the corticospinal tract, which is commonly used as a reference to set TMS intensity, may not correspond to the excitability of cortico-cortical pathways.
Collapse
Affiliation(s)
- Giacomo Guidali
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Agnese Zazio
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Delia Lucarelli
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Eleonora Marcantoni
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Antonietta Stango
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Guido Barchiesi
- Department of Philosophy, University of Milano, Milan, Italy
| | - Marta Bortoletto
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| |
Collapse
|
3
|
Casarotto A, Dolfini E, Fadiga L, Koch G, D'Ausilio A. Cortico-cortical paired associative stimulation conditioning superficial ventral premotor cortex-primary motor cortex connectivity influences motor cortical activity during precision grip. J Physiol 2023; 601:3945-3960. [PMID: 37526070 DOI: 10.1113/jp284500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 07/10/2023] [Indexed: 08/02/2023] Open
Abstract
The ventral premotor cortex (PMv) and primary motor cortex (M1) represent critical nodes of a parietofrontal network involved in grasping actions, such as power and precision grip. Here, we investigated how the functional PMv-M1 connectivity drives the dissociation between these two actions. We applied a PMv-M1 cortico-cortical paired associative stimulation (cc-PAS) protocol, stimulating M1 in both postero-anterior (PA) and antero-posterior (AP) directions, in order to induce long-term changes in the activity of different neuronal populations within M1. We evaluated the motor-evoked potential (MEP) amplitude, MEP latency and cortical silent period, in both PA and AP, during the isometric execution of precision and power grip, before and after the PMv-M1 cc-PAS. The repeated activation of the PMv-M1 cortico-cortical network with PA orientation over M1 did not change MEP amplitude or cortical silent period duration during both actions. In contrast, the PMv-M1 cc-PAS stimulation of M1 with an AP direction led to a specific modulation of precision grip motor drive. In particular, MEPs tested with AP stimulation showed a selective increase of corticospinal excitability during precision grip. These findings suggest that the more superficial M1 neuronal populations recruited by the PMv input are involved preferentially in the execution of precision grip actions. KEY POINTS: Ventral premotor cortex (PMv)-primary motor cortex (M1) cortico-cortical paired associative stimulation (cc-PAS) with different coil orientation targets dissociable neural populations. PMv-M1 cc-PAS with M1 antero-posterior coil orientation specifically modulates corticospinal excitability during precision grip. Superficial M1 populations are involved preferentially in the execution of precision grip. A plasticity induction protocol targeting the specific PMv-M1 subpopulation might have important translational value for the rehabilitation of hand function.
Collapse
Affiliation(s)
- Andrea Casarotto
- IIT@UniFe Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Ferrara, Italy
- Department of Neuroscience and Rehabilitation, Section of Physiology, Università di Ferrara, Ferrara, Italy
| | - Elisa Dolfini
- Department of Neuroscience and Rehabilitation, Section of Physiology, Università di Ferrara, Ferrara, Italy
| | - Luciano Fadiga
- IIT@UniFe Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Ferrara, Italy
- Department of Neuroscience and Rehabilitation, Section of Physiology, Università di Ferrara, Ferrara, Italy
| | - Giacomo Koch
- IIT@UniFe Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Ferrara, Italy
- Department of Neuroscience and Rehabilitation, Section of Physiology, Università di Ferrara, Ferrara, Italy
- Experimental Neuropsychophysiology Laboratory, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Alessandro D'Ausilio
- IIT@UniFe Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Ferrara, Italy
- Department of Neuroscience and Rehabilitation, Section of Physiology, Università di Ferrara, Ferrara, Italy
| |
Collapse
|
4
|
Spampinato DA, Ibanez J, Rocchi L, Rothwell J. Motor potentials evoked by transcranial magnetic stimulation: interpreting a simple measure of a complex system. J Physiol 2023; 601:2827-2851. [PMID: 37254441 PMCID: PMC10952180 DOI: 10.1113/jp281885] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 05/18/2023] [Indexed: 06/01/2023] Open
Abstract
Transcranial magnetic stimulation (TMS) is a non-invasive technique that is increasingly used to study the human brain. One of the principal outcome measures is the motor-evoked potential (MEP) elicited in a muscle following TMS over the primary motor cortex (M1), where it is used to estimate changes in corticospinal excitability. However, multiple elements play a role in MEP generation, so even apparently simple measures such as peak-to-peak amplitude have a complex interpretation. Here, we summarize what is currently known regarding the neural pathways and circuits that contribute to the MEP and discuss the factors that should be considered when interpreting MEP amplitude measured at rest in the context of motor processing and patients with neurological conditions. In the last part of this work, we also discuss how emerging technological approaches can be combined with TMS to improve our understanding of neural substrates that can influence MEPs. Overall, this review aims to highlight the capabilities and limitations of TMS that are important to recognize when attempting to disentangle sources that contribute to the physiological state-related changes in corticomotor excitability.
Collapse
Affiliation(s)
- Danny Adrian Spampinato
- Department of Clinical and Movement NeurosciencesUniversity College LondonLondonUK
- Department of Human NeurosciencesSapienza University of RomeRomeItaly
- Department of Clinical and Behavioral NeurologyIRCCS Santa Lucia FoundationRomeItaly
| | - Jaime Ibanez
- Department of Clinical and Movement NeurosciencesUniversity College LondonLondonUK
- BSICoS group, I3A Institute and IIS AragónUniversity of ZaragozaZaragozaSpain
- Department of Bioengineering, Centre for NeurotechnologiesImperial College LondonLondonUK
| | - Lorenzo Rocchi
- Department of Clinical and Movement NeurosciencesUniversity College LondonLondonUK
- Department of Medical Sciences and Public HealthUniversity of CagliariCagliariItaly
| | - John Rothwell
- Department of Clinical and Movement NeurosciencesUniversity College LondonLondonUK
| |
Collapse
|
5
|
Van Dam JM, Graetz L, Pitcher JB, Goldsworthy MR. The effects of age and biological sex on the association between I-wave recruitment and the response to cTBS: an exploratory study. Brain Res 2023; 1810:148359. [PMID: 37030620 DOI: 10.1016/j.brainres.2023.148359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 03/24/2023] [Accepted: 04/04/2023] [Indexed: 04/09/2023]
Abstract
The neuroplastic response to continuous theta burst stimulation (cTBS) is inherently variable. The measurement of I-wave latencies has been shown to strongly predict the magnitude and direction of the response to cTBS, whereby longer latencies are associated with stronger long-term depression-like responses. However, potential differences in this association relating to age and sex have not been explored. We performed cTBS and measured I-wave recruitment (via MEP latencies) in 66 participants (31 female) ranging in age from 11 to 78 years. The influence of age and sex on the association between I-wave recruitment and the response to cTBS was tested using linear regression models. In contrast to previous studies, there was not a significant association between I-wave latencies and cTBS response at the group level (p = 0.142, R2 = 0.033). However, there were interactions between I-waves and both age and sex when predicting cTBS response. Subgroup analysis revealed that preferential late I-wave recruitment predicted cTBS response in adolescent females, but not in adolescent or adult males or adult females. These data suggest that the generalisability of I-wave measurement in predicting the response to cTBS may be lower than initially believed. Prediction models should include age and sex, rather than I-wave latencies alone, as our findings suggest that, while each factor alone is not a strong predictor, these factors interact to influence the response to cTBS.
Collapse
Affiliation(s)
- Jago M Van Dam
- Robinson Research Institute, University of Adelaide, Adelaide, South Australia 5005, Australia; Lifespan Human Neurophysiology Group, School of Biomedicine, University of Adelaide, Adelaide, South Australia 5000, Australia; Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia
| | - Lynton Graetz
- Lifespan Human Neurophysiology Group, School of Biomedicine, University of Adelaide, Adelaide, South Australia 5000, Australia; Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia
| | - Julia B Pitcher
- Robinson Research Institute, University of Adelaide, Adelaide, South Australia 5005, Australia; Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Deakin University, Geelong, Victoria 3220, Australia
| | - Mitchell R Goldsworthy
- Lifespan Human Neurophysiology Group, School of Biomedicine, University of Adelaide, Adelaide, South Australia 5000, Australia; Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia.
| |
Collapse
|
6
|
Anil S, Lu H, Rotter S, Vlachos A. Repetitive transcranial magnetic stimulation (rTMS) triggers dose-dependent homeostatic rewiring in recurrent neuronal networks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533396. [PMID: 36993387 PMCID: PMC10055183 DOI: 10.1101/2023.03.20.533396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used to induce neuronal plasticity in healthy individuals and patients. Designing effective and reproducible rTMS protocols poses a major challenge in the field as the underlying biomechanisms remain elusive. Current clinical protocol designs are often based on studies reporting rTMS-induced long-term potentiation or depression of synaptic transmission. Herein, we employed computational modeling to explore the effects of rTMS on long-term structural plasticity and changes in network connectivity. We simulated a recurrent neuronal network with homeostatic structural plasticity between excitatory neurons, and demonstrated that this mechanism was sensitive to specific parameters of the stimulation protocol (i.e., frequency, intensity, and duration of stimulation). The feedback-inhibition initiated by network stimulation influenced the net stimulation outcome and hindered the rTMS-induced homeostatic structural plasticity, highlighting the role of inhibitory networks. These findings suggest a novel mechanism for the lasting effects of rTMS, i.e., rTMS-induced homeostatic structural plasticity, and highlight the importance of network inhibition in careful protocol design, standardization, and optimization of stimulation.
Collapse
Affiliation(s)
- Swathi Anil
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Han Lu
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - Stefan Rotter
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
- Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
- Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
- Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| |
Collapse
|
7
|
Van Malderen S, Hehl M, Verstraelen S, Swinnen SP, Cuypers K. Dual-site TMS as a tool to probe effective interactions within the motor network: a review. Rev Neurosci 2023; 34:129-221. [PMID: 36065080 DOI: 10.1515/revneuro-2022-0020] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 07/02/2022] [Indexed: 02/07/2023]
Abstract
Dual-site transcranial magnetic stimulation (ds-TMS) is well suited to investigate the causal effect of distant brain regions on the primary motor cortex, both at rest and during motor performance and learning. However, given the broad set of stimulation parameters, clarity about which parameters are most effective for identifying particular interactions is lacking. Here, evidence describing inter- and intra-hemispheric interactions during rest and in the context of motor tasks is reviewed. Our aims are threefold: (1) provide a detailed overview of ds-TMS literature regarding inter- and intra-hemispheric connectivity; (2) describe the applicability and contributions of these interactions to motor control, and; (3) discuss the practical implications and future directions. Of the 3659 studies screened, 109 were included and discussed. Overall, there is remarkable variability in the experimental context for assessing ds-TMS interactions, as well as in the use and reporting of stimulation parameters, hindering a quantitative comparison of results across studies. Further studies examining ds-TMS interactions in a systematic manner, and in which all critical parameters are carefully reported, are needed.
Collapse
Affiliation(s)
- Shanti Van Malderen
- Department of Movement Sciences, Movement Control & Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Heverlee 3001, Belgium.,Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek 3590, Belgium
| | - Melina Hehl
- Department of Movement Sciences, Movement Control & Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Heverlee 3001, Belgium.,Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek 3590, Belgium
| | - Stefanie Verstraelen
- Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek 3590, Belgium
| | - Stephan P Swinnen
- Department of Movement Sciences, Movement Control & Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Heverlee 3001, Belgium.,KU Leuven, Leuven Brain Institute (LBI), Leuven, Belgium
| | - Koen Cuypers
- Department of Movement Sciences, Movement Control & Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Heverlee 3001, Belgium.,Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek 3590, Belgium
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Li Z, Zhang J, Peterchev AV, Goetz SM. Modular pulse synthesizer for transcranial magnetic stimulation with fully adjustable pulse shape and sequence. J Neural Eng 2022; 19:10.1088/1741-2552/ac9d65. [PMID: 36301685 PMCID: PMC10206176 DOI: 10.1088/1741-2552/ac9d65] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/25/2022] [Indexed: 01/11/2023]
Abstract
The temporal shape of a pulse in transcranial magnetic stimulation (TMS) influences which neuron populations are activated preferentially as well as the strength and even direction of neuromodulation effects. Furthermore, various pulse shapes differ in their efficiency, coil heating, sensory perception, and clicking sound. However, the available TMS pulse shape repertoire is still very limited to a few biphasic, monophasic, and polyphasic pulses with sinusoidal or near-rectangular shapes. Monophasic pulses, though found to be more selective and stronger in neuromodulation, are generated inefficiently and therefore only available in simple low-frequency repetitive protocols. Despite a strong interest to exploit the temporal effects of TMS pulse shapes and pulse sequences, waveform control is relatively inflexible and only possible parametrically within certain limits. Previously proposed approaches for flexible pulse shape control, such as through power electronic inverters, have significant limitations: The semiconductor switches can fail under the immense electrical stress associated with free pulse shaping, and most conventional power inverter topologies are incapable of generating smooth electric fields or existing pulse shapes. Leveraging intensive preliminary work on modular power electronics, we present a modular pulse synthesizer (MPS) technology that can, for the first time, flexibly generate high-power TMS pulses (one-side peak ∼4000 V, ∼8000 A) with user-defined electric field shape as well as rapid sequences of pulses with high output quality. The circuit topology breaks the problem of simultaneous high power and switching speed into smaller, manageable portions, distributed across several identical modules. In consequence, the MPS TMS techology can use semiconductor devices with voltage and current ratings lower than the overall pulse voltage and distribute the overall switching of several hundred kilohertz among multiple transistors. MPS TMS can synthesize practically any pulse shape, including conventional ones, with fine quantization of the induced electric field (⩽17% granularity without modulation and ∼300 kHz bandwidth). Moreover, the technology allows optional symmetric differential coil driving so that the average electric potential of the coil, in contrast to conventional TMS devices, stays constant to prevent capacitive artifacts in sensitive recording amplifiers, such as electroencephalography. MPS TMS can enable the optimization of stimulation paradigms for more sophisticated probing of brain function as well as stronger and more selective neuromodulation, further expanding the parameter space available to users.
Collapse
Affiliation(s)
- Z Li
- Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, United States of America
| | - J Zhang
- Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, United States of America
| | - A V Peterchev
- Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, United States of America
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, United States of America
- Department of Neurosurgery, Duke University, Durham, NC 27710, United States of America
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States of America
- Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, United States of America
| | - S M Goetz
- Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, United States of America
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, United States of America
- Department of Neurosurgery, Duke University, Durham, NC 27710, United States of America
- Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, United States of America
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| |
Collapse
|
10
|
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]
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Nazarova M, Novikov P, Ivanina E, Kozlova K, Dobrynina L, Nikulin VV. Mapping of multiple muscles with transcranial magnetic stimulation: absolute and relative test-retest reliability. Hum Brain Mapp 2021; 42:2508-2528. [PMID: 33682975 PMCID: PMC8090785 DOI: 10.1002/hbm.25383] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 02/09/2021] [Accepted: 02/11/2021] [Indexed: 12/13/2022] Open
Abstract
The spatial accuracy of transcranial magnetic stimulation (TMS) may be as small as a few millimeters. Despite such great potential, navigated TMS (nTMS) mapping is still underused for the assessment of motor plasticity, particularly in clinical settings. Here, we investigate the within-limb somatotopy gradient as well as absolute and relative reliability of three hand muscle cortical representations (MCRs) using a comprehensive grid-based sulcus-informed nTMS motor mapping. We enrolled 22 young healthy male volunteers. Two nTMS mapping sessions were separated by 5-10 days. Motor evoked potentials were obtained from abductor pollicis brevis (APB), abductor digiti minimi, and extensor digitorum communis. In addition to individual MRI-based analysis, we studied normalized MNI MCRs. For the reliability assessment, we calculated intraclass correlation and the smallest detectable change. Our results revealed a somatotopy gradient reflected by APB MCR having the most lateral location. Reliability analysis showed that the commonly used metrics of MCRs, such as areas, volumes, centers of gravity (COGs), and hotspots had a high relative and low absolute reliability for all three muscles. For within-limb TMS somatotopy, the most common metrics such as the shifts between MCR COGs and hotspots had poor relative reliability. However, overlaps between different muscle MCRs were highly reliable. We, thus, provide novel evidence that inter-muscle MCR interaction can be reliably traced using MCR overlaps while shifts between the COGs and hotspots of different MCRs are not suitable for this purpose. Our results have implications for the interpretation of nTMS motor mapping results in healthy subjects and patients with neurological conditions.
Collapse
Affiliation(s)
- Maria Nazarova
- Center for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of EconomicsMoscowRussian Federation
- Federal State Budgetary Institution «Federal center of brain research and neurotechnologies» of the Federal Medical Biological AgencyMoscowRussian Federation
| | - Pavel Novikov
- Center for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of EconomicsMoscowRussian Federation
| | - Ekaterina Ivanina
- Center for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of EconomicsMoscowRussian Federation
| | - Ksenia Kozlova
- Center for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of EconomicsMoscowRussian Federation
| | | | - Vadim V. Nikulin
- Center for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of EconomicsMoscowRussian Federation
- Department of NeurologyMax Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| |
Collapse
|
14
|
Opie GM, Liao WY, Semmler JG. Interactions Between Cerebellum and the Intracortical Excitatory Circuits of Motor Cortex: a Mini-Review. CEREBELLUM (LONDON, ENGLAND) 2021; 21:159-166. [PMID: 33978934 DOI: 10.1007/s12311-021-01278-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Accepted: 05/03/2021] [Indexed: 12/28/2022]
Abstract
Interactions between cerebellum (CB) and primary motor cortex (M1) are critical for effective motor function. Although the associated neurophysiological processes are yet to be fully characterised, a growing body of work using non-invasive brain stimulation (NIBS) techniques has significantly progressed our current understanding. In particular, recent developments with both transcranial magnetic (TMS) and direct current (tDCS) stimulation suggest that CB modulates the activity of local excitatory interneuronal circuits within M1. These circuits are known to be important both physiologically and functionally, and understanding the nature of their connectivity with CB therefore has the potential to provide important insight for NIBS applications. Consequently, this mini-review provides an overview of the emerging literature that has investigated interactions between CB and the intracortical excitatory circuits of M1.
Collapse
Affiliation(s)
- George M Opie
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Wei-Yeh Liao
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - John G Semmler
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, 5005, Australia.
| |
Collapse
|
15
|
Spampinato D, Avci E, Rothwell J, Rocchi L. Frequency-dependent modulation of cerebellar excitability during the application of non-invasive alternating current stimulation. Brain Stimul 2021; 14:277-283. [PMID: 33482375 PMCID: PMC7970622 DOI: 10.1016/j.brs.2021.01.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/09/2020] [Accepted: 01/12/2021] [Indexed: 12/30/2022] Open
Abstract
Background it is well-known that the cerebellum is critical for the integrity of motor and cognitive actions. Applying non-invasive brain stimulation techniques over this region results in neurophysiological and behavioural changes, which have been associated with the modulation of cerebellar-cerebral cortex connectivity. Here, we investigated whether online application of cerebellar transcranial alternating current stimulation (tACS) results in changes to this pathway. Methods thirteen healthy individuals participated in two sessions of cerebellar tACS delivered at different frequencies (5Hz and 50Hz). We used transcranial magnetic stimulation to measure cerebellar-motor cortex (M1) inhibition (CBI), short-intracortical inhibition (SICI) and short-afferent inhibition (SAI) before, during and after the application of tACS. Results we found that CBI was specifically strengthened during the application of 5Hz cerebellar tACS. No changes were detected immediately following the application of 5Hz stimulation, nor at any time point with 50Hz stimulation. We also found no changes to M1 intracortical circuits (i.e. SICI) or sensorimotor interaction (i.e. SAI), indicating that the effects of 5Hz tACS over the cerebellum are site-specific. Conclusions cerebellar tACS can modulate cerebellar excitability in a time- and frequency-dependent manner. Additionally, cerebellar tACS does not appear to induce any long-lasting effects (i.e. plasticity), suggesting that stimulation enhances oscillations within the cerebellum only throughout the stimulation period. As such, cerebellar tACS may have significant implications for diseases manifesting with abnormal cerebellar oscillatory activity and also for future behavioural studies. Cerebellar tACS increases the inhibitory tone that the cerebellum exerts over M1 (CBI). CBI changes were found only during the online application of 5Hz tACS and not immediately following stimulation. The effects are specific to the cerebellum, as no changes were found in intracortical measures (e.g. SICI and SAI).
Collapse
Affiliation(s)
- Danny Spampinato
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, United Kingdom; Non-invasive Brain Stimulation Unit, IRCCS Santa Lucia Foundation, Via Ardeatina 306/354, 00142, Rome, Italy.
| | - Esin Avci
- Department of Sport and Sport Science, Institute of Biology, University of Freiburg, Germany
| | - John Rothwell
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, United Kingdom
| | - Lorenzo Rocchi
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, United Kingdom
| |
Collapse
|
16
|
Modulation of Motor Cortex Plasticity by Repetitive Paired-Pulse TMS at Late I-Wave Intervals Is Influenced by Intracortical Excitability. Brain Sci 2021; 11:brainsci11010121. [PMID: 33477434 PMCID: PMC7829868 DOI: 10.3390/brainsci11010121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 01/28/2023] Open
Abstract
The late indirect (I)-waves recruited by transcranial magnetic stimulation (TMS) over primary motor cortex (M1) can be modulated using I-wave periodicity repetitive TMS (iTMS). The purpose of this study was to determine if the response to iTMS is influenced by different interstimulus intervals (ISIs) targeting late I-waves, and whether these responses were associated with individual variations in intracortical excitability. Seventeen young (27.2 ± 6.4 years, 12 females) healthy adults received iTMS at late I-wave intervals (4.0, 4.5, and 5.0 ms) in three separate sessions. Changes due to each intervention were examined with motor evoked potential (MEP) amplitudes and short-interval intracortical facilitation (SICF) using both posterior-anterior (PA) and anterior-posterior (AP) TMS current directions. Changes in MEP amplitude and SICF were influenced by iTMS ISI, with the greatest facilitation for ISIs at 4 and 5 ms with PA TMS, and 4 ms with AP TMS. Maximum SICF at baseline (irrespective of ISI) was associated with increased iTMS response, but only for PA stimulation. These results suggest that modifying iTMS parameters targeting late I-waves can influence M1 plasticity. They also suggest that maximum SICF may be a means by which responders to iTMS targeting the late I-waves could be identified.
Collapse
|