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Di Libero T, Carissimo C, Cerro G, Abbatecola AM, Marino A, Miele G, Ferrigno L, Rodio A. An Overall Automated Architecture Based on the Tapping Test Measurement Protocol: Hand Dexterity Assessment through an Innovative Objective Method. SENSORS (BASEL, SWITZERLAND) 2024; 24:4133. [PMID: 39000912 PMCID: PMC11244415 DOI: 10.3390/s24134133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 07/16/2024]
Abstract
The present work focuses on the tapping test, which is a method that is commonly used in the literature to assess dexterity, speed, and motor coordination by repeatedly moving fingers, performing a tapping action on a flat surface. During the test, the activation of specific brain regions enhances fine motor abilities, improving motor control. The research also explores neuromuscular and biomechanical factors related to finger dexterity, revealing neuroplastic adaptation to repetitive movements. To give an objective evaluation of all cited physiological aspects, this work proposes a measurement architecture consisting of the following: (i) a novel measurement protocol to assess the coordinative and conditional capabilities of a population of participants; (ii) a suitable measurement platform, consisting of synchronized and non-invasive inertial sensors to be worn at finger level; (iii) a data analysis processing stage, able to provide the final user (medical doctor or training coach) with a plethora of useful information about the carried-out tests, going far beyond state-of-the-art results from classical tapping test examinations. Particularly, the proposed study underscores the importance interdigital autonomy for complex finger motions, despite the challenges posed by anatomical connections; this deepens our understanding of upper limb coordination and the impact of neuroplasticity, holding significance for motor abilities assessment, improvement, and therapeutic strategies to enhance finger precision. The proof-of-concept test is performed by considering a population of college students. The obtained results allow us to consider the proposed architecture to be valuable for many application scenarios, such as the ones related to neurodegenerative disease evolution monitoring.
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Affiliation(s)
- Tommaso Di Libero
- Department of Human, Social and Health Sciences, University of Cassino and Southern Lazio, 03043 Cassino, Italy
| | - Chiara Carissimo
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, 86100 Campobasso, Italy
| | - Gianni Cerro
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, 86100 Campobasso, Italy
| | - Angela Marie Abbatecola
- Department of Human, Social and Health Sciences, University of Cassino and Southern Lazio, 03043 Cassino, Italy
- Alzheimer's Disease Day Clinics, Azienda ria Locale, 03100 Frosinone, Italy
| | - Alessandro Marino
- Department of Electrical and Information Engineering, University of Cassino and Southern Lazio, 03043 Cassino, Italy
| | - Gianfranco Miele
- Department of Electrical and Information Engineering, University of Cassino and Southern Lazio, 03043 Cassino, Italy
| | - Luigi Ferrigno
- Department of Electrical and Information Engineering, University of Cassino and Southern Lazio, 03043 Cassino, Italy
| | - Angelo Rodio
- Department of Human, Social and Health Sciences, University of Cassino and Southern Lazio, 03043 Cassino, Italy
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2
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Uehara K, Togo H, Hanakawa T. Precise motor rhythmicity relies on motor network responsivity. Cereb Cortex 2022; 33:4432-4447. [PMID: 36218995 DOI: 10.1093/cercor/bhac353] [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: 05/10/2022] [Revised: 08/14/2022] [Accepted: 08/15/2022] [Indexed: 11/14/2022] Open
Abstract
Rhythmic movements are the building blocks of human behavior. However, given that rhythmic movements are achieved through complex interactions between neural modules, it remains difficult to clarify how the central nervous system controls motor rhythmicity. Here, using a novel tempo-precision trade-off paradigm, we first modeled interindividual behavioral differences in tempo-dependent rhythmicity for various external tempi. We identified 2 behavioral extremes: conventional and paradoxical tempo-precision trade-off types. We then explored the neural substrates of these behavioral differences using task and resting-state functional magnetic resonance imaging. We found that the responsibility of interhemispheric motor network connectivity to tempi was a key to the behavioral repertoire. In the paradoxical trade-off type, interhemispheric connectivity was low at baseline but increased in response to increasing tempo; in the conventional trade-off type, strong baseline connectivity was coupled with low responsivity. These findings suggest that tunable interhemispheric connectivity underlies tempo-dependent rhythmicity control.
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Affiliation(s)
- Kazumasa Uehara
- Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan.,Division of Neural Dynamics, Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Aichi 4448585, Japan.,Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 4448585, Japan
| | - Hiroki Togo
- Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan.,Department of Integrated Neuroanatomy and Neuroimaging, Kyoto University Graduate School of Medicine, Kyoto 6068501, Japan
| | - Takashi Hanakawa
- Department of Advanced Neuroimaging, Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan.,Department of Integrated Neuroanatomy and Neuroimaging, Kyoto University Graduate School of Medicine, Kyoto 6068501, Japan
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3
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Hervault M, Zanone PG, Buisson JC, Huys R. Hold your horses: Differences in EEG correlates of inhibition in cancelling and stopping an action. Neuropsychologia 2022; 172:108255. [PMID: 35513065 DOI: 10.1016/j.neuropsychologia.2022.108255] [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: 10/11/2021] [Revised: 03/16/2022] [Accepted: 04/28/2022] [Indexed: 10/18/2022]
Abstract
Behavioral adaptation to changing contextual contingencies often requires the rapid inhibition of planned or ongoing actions. Inhibitory control has been mostly studied using the stop-signal paradigm, which conceptualizes action inhibition as the outcome of a race between independent GO and STOP processes. Inhibition is predominantly considered to be independent of action type, yet it is questionable whether this conceptualization can apply to stopping an ongoing action. To test the claimed generality of action inhibition, we investigated behavioral stop-signal reaction time (SSRT) and scalp electroencephalographic (EEG) activity in two inhibition contexts: Using variants of the stop-signal task, we asked participants to cancel a prepared-discrete action or to stop an ongoing-rhythmic action in reaction to a STOP signal. The behavioral analysis revealed that the discrete and rhythmic SSRTs were not correlated. The EEG analysis showed that the STOP signal evoked frontocentral activity in the time and frequency domains (Delta/Theta range) in a task-specific manner: The P3 onset latency was the best correlate of discrete SSRT whereas N2/P3 peak-to-peak amplitude was the best correlate of rhythmic SSRT. These findings do not support a conceptualization of inhibition as action-independent but rather suggest that the differential engagement of both components of the N2/P3-complex as a function of action type pertains to functionally independent inhibition subprocesses.
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Affiliation(s)
- Mario Hervault
- Centre de Recherche Cerveau et Cognition, UMR 5549 CNRS, Université Toulouse 3 Paul Sabatier, France.
| | - Pier-Giorgio Zanone
- Centre de Recherche Cerveau et Cognition, UMR 5549 CNRS, Université Toulouse 3 Paul Sabatier, France
| | - Jean-Christophe Buisson
- Institut de Recherche en Informatique de Toulouse, UMR 5505 CNRS, Université Toulouse 3 Paul Sabatier, France
| | - Raoul Huys
- Centre de Recherche Cerveau et Cognition, UMR 5549 CNRS, Université Toulouse 3 Paul Sabatier, France
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4
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Xu J, Lopez AJ, Hoque MM, Borich MR, Kesar TM. Temporal Profile of Descending Cortical Modulation of Spinal Excitability: Group and Individual-Specific Effects. Front Integr Neurosci 2022; 15:777741. [PMID: 35197831 PMCID: PMC8859157 DOI: 10.3389/fnint.2021.777741] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/21/2021] [Indexed: 11/16/2022] Open
Abstract
Sensorimotor control is modulated through complex interactions between descending corticomotor pathways and ascending sensory inputs. Pairing sub-threshold transcranial magnetic stimulation (TMS) with peripheral nerve stimulation (PNS) modulates the Hoffmann’s reflex (H-reflex), providing a neurophysiologic probe into the influence of descending cortical drive on spinal segmental circuits. However, individual variability in the timing and magnitude of H-reflex modulation is poorly understood. Here, we varied the inter-stimulus interval (ISI) between TMS and PNS to systematically manipulate the relative timing of convergence of descending TMS-induced volleys with respect to ascending PNS-induced afferent volleys in the spinal cord to: (1) characterize effective connectivity between the primary motor cortex (M1) and spinal circuits, mediated by both direct, fastest-conducting, and indirect, slower-conducting descending pathways; and (2) compare the effect of individual-specific vs. standard ISIs. Unconditioned and TMS-conditioned H-reflexes (24 different ISIs ranging from −6 to 12 ms) were recorded from the soleus muscle in 10 able-bodied individuals. The magnitude of H-reflex modulation at individualized ISIs (earliest facilitation delay or EFD and individual-specific peak facilitation) was compared with standard ISIs. Our results revealed a significant effect of ISI on H-reflex modulation. ISIs eliciting earliest-onset facilitation (EFD 0 ms) ranged from −3 to −5 ms across individuals. No difference in the magnitude of facilitation was observed at EFD 0 ms vs. a standardized short-interval ISI of −1.5 ms. Peak facilitation occurred at longer ISIs, ranging from +3 to +11 ms. The magnitude of H-reflex facilitation derived using an individual-specific peak facilitation was significantly larger than facilitation observed at a standardized longer-interval ISI of +10 ms. Our results suggest that unique insights can be provided with individual-specific measures of top-down effective connectivity mediated by direct and/or fastest-conducting pathways (indicated by the magnitude of facilitation observed at EFD 0 ms) and other descending pathways that encompass relatively slower and/or indirect connections from M1 to spinal circuits (indicated by peak facilitation and facilitation at longer ISIs). By comprehensively characterizing the temporal profile and inter-individual variability of descending modulation of spinal reflexes, our findings provide methodological guidelines and normative reference values to inform future studies on neurophysiological correlates of the complex array of descending neural connections between M1 and spinal circuits.
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Affiliation(s)
- Jiang Xu
- Department of Rehabilitation Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States
| | - Alejandro J. Lopez
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States
- Neuroscience Graduate Program, Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA, United States
| | - Maruf M. Hoque
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States
| | - Michael R. Borich
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States
| | - Trisha M. Kesar
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States
- *Correspondence: Trisha M. Kesar
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Hervault M, Zanone PG, Buisson JC, Huys R. Cortical sensorimotor activity in the execution and suppression of discrete and rhythmic movements. Sci Rep 2021; 11:22364. [PMID: 34785710 PMCID: PMC8595306 DOI: 10.1038/s41598-021-01368-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/20/2021] [Indexed: 11/09/2022] Open
Abstract
Although the engagement of sensorimotor cortices in movement is well documented, the functional relevance of brain activity patterns remains ambiguous. Especially, the cortical engagement specific to the pre-, within-, and post-movement periods is poorly understood. The present study addressed this issue by examining sensorimotor EEG activity during the performance as well as STOP-signal cued suppression of movements pertaining to two distinct classes, namely, discrete vs. ongoing rhythmic movements. Our findings indicate that the lateralized readiness potential (LRP), which is classically used as a marker of pre-movement processing, indexes multiple pre- and in- movement-related brain dynamics in a movement-class dependent fashion. In- and post-movement event-related (de)synchronization (ERD/ERS) observed in the Mu (8-13 Hz) and Beta (15-30 Hz) frequency ranges were associated with estimated brain sources in both motor and somatosensory cortical areas. Notwithstanding, Beta ERS occurred earlier following cancelled than actually performed movements. In contrast, Mu power did not vary. Whereas Beta power may reflect the evaluation of the sensory predicted outcome, Mu power might engage in linking perception to action. Additionally, the rhythmic movement forced stop (only) showed a post-movement Mu/Beta rebound, which might reflect an active "clearing-out" of the motor plan and its feedback-based online control. Overall, the present study supports the notion that sensorimotor EEG modulations are key markers to investigate control or executive processes, here initiation and inhibition, which are exerted when performing distinct movement classes.
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Affiliation(s)
- Mario Hervault
- Centre de Recherche Cerveau et Cognition, UMR 5549, Pavillon Baudot CHU Purpan, CNRS - Université Toulouse 3 Paul Sabatier, Toulouse, France.
| | - Pier-Giorgio Zanone
- Centre de Recherche Cerveau et Cognition, UMR 5549, Pavillon Baudot CHU Purpan, CNRS - Université Toulouse 3 Paul Sabatier, Toulouse, France
| | - Jean-Christophe Buisson
- Institut de Recherche en Informatique de Toulouse - UMR 5505, CNRS - Université Toulouse 3 Paul Sabatier, Toulouse, France
| | - Raoul Huys
- Centre de Recherche Cerveau et Cognition, UMR 5549, Pavillon Baudot CHU Purpan, CNRS - Université Toulouse 3 Paul Sabatier, Toulouse, France
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6
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Hervault M, Zanone PG, Buisson JC, Huys R. Multiple Brain Sources Are Differentially Engaged in the Inhibition of Distinct Action Types. J Cogn Neurosci 2021; 34:258-272. [PMID: 34813646 DOI: 10.1162/jocn_a_01794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Most studies contributing to identify the brain network for inhibitory control have investigated the cancelation of prepared-discrete actions, thus focusing on an isolated and short-lived chunk of human behavior. Aborting ongoing-continuous actions is an equally crucial ability but remains little explored. Although discrete and ongoing-continuous rhythmic actions are associated with partially overlapping yet largely distinct brain activations, it is unknown whether the inhibitory network operates similarly in both situations. Thus, distinguishing between action types constitutes a powerful means to investigate whether inhibition is a generic function. We, therefore, used independent component analysis (ICA) of EEG data and show that canceling a discrete action and aborting a rhythmic action rely on independent brain components. The ICA showed that a delta/theta power increase generically indexed inhibitory activity, whereas N2 and P3 ERP waves did so in an action-specific fashion. The action-specific components were generated by partially distinct brain sources, which indicates that the inhibitory network is engaged differently when canceling a prepared-discrete action versus aborting an ongoing-continuous action. In particular, increased activity was estimated in precentral gyri and posterior parts of the cingulate cortex for action canceling, whereas an enhanced activity was found in more frontal gyri and anterior parts of the cingulate cortex for action aborting. Overall, the present findings support the idea that inhibitory control is differentially implemented according to the type of action to revise.
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7
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Leukel C, Kurz A. Determining the types of descending waves from transcranial magnetic stimulation measured with conditioned H-reflexes in humans. Eur J Neurosci 2021; 54:5038-5046. [PMID: 33966324 DOI: 10.1111/ejn.15308] [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: 10/17/2020] [Revised: 04/09/2021] [Accepted: 05/02/2021] [Indexed: 11/30/2022]
Abstract
Non-invasive techniques are scarce with which human (motor) cortical mechanisms can be investigated. In a series of previous experiments, we have applied an advanced form of conditioning technique with transcranial magnetic stimulation (TMS) and peripheral nerve stimulation by which excitability changes at the laminar level in the primary motor cortex can be estimated. This method builds on the assumption that the first of subsequent corticospinal waves from TMS which is assessed with H-reflexes (called early facilitation) results from indirect excitation of corticospinal neurons in motor cortex (I-wave) and not direct excitation of corticospinal axons (D-wave). So far, we have not provided strong experimental evidence that this is actually the case. In the present study, we therefore compared temporal differences of the early facilitation between transcranial magnetic and electrical stimulation (TES). TES is known to excite the axons of corticospinal neurons. TES in our study caused a temporal shift of the early facilitation of H-reflexes in all subjects compared to TMS, which indicates that the early facilitation with TMS is indeed produced by an I-wave. Additionally, we investigated temporal shifts of the early facilitation with different TMS intensities and two TMS coils. It has long been known that TMS with higher intensities can induce a D-wave. Accordingly, we found that TMS with an intensity of 150% of resting motor threshold compared to 130%/110% results in a temporal shift of the early facilitation, indicating the presence of a D-wave. This effect was dependent on the coil type.
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Affiliation(s)
- Christian Leukel
- Department of Sport Science, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Alexander Kurz
- Department of Sport Science, University of Freiburg, Freiburg, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
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Cleland BT, Madhavan S. Ipsilateral Motor Pathways and Transcallosal Inhibition During Lower Limb Movement After Stroke. Neurorehabil Neural Repair 2021; 35:367-378. [PMID: 33703951 DOI: 10.1177/1545968321999049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Stroke rehabilitation may be improved with a better understanding of the contribution of ipsilateral motor pathways to the paretic limb and alterations in transcallosal inhibition. Few studies have evaluated these factors during dynamic, bilateral lower limb movements, and it is unclear whether they relate to functional outcomes. OBJECTIVE Determine if lower limb ipsilateral excitability and transcallosal inhibition after stroke depend on target limb, task, or number of limbs involved, and whether these factors are related to clinical measures. METHODS In 29 individuals with stroke, ipsilateral and contralateral responses to transcranial magnetic stimulation were measured in the paretic and nonparetic tibialis anterior during dynamic (unilateral or bilateral ankle dorsiflexion/plantarflexion) and isometric (unilateral dorsiflexion) conditions. Relative ipsilateral excitability and transcallosal inhibition were assessed. Fugl-Meyer, ankle movement accuracy, and walking characteristics were assessed. RESULTS Relative ipsilateral excitability was greater during dynamic than isometric conditions in the paretic limb (P ≤ .02) and greater in the paretic than the nonparetic limb during dynamic conditions (P ≤ .004). Transcallosal inhibition was greater in the ipsilesional than contralesional hemisphere (P = .002) and during dynamic than isometric conditions (P = .03). Greater ipsilesional transcallosal inhibition was correlated with better ankle movement accuracy (R2 = 0.18, P = .04). Greater contralateral excitability to the nonparetic limb was correlated with improved walking symmetry (R2 = 0.19, P = .03). CONCLUSIONS Ipsilateral pathways have increased excitability to the paretic limb, particularly during dynamic tasks. Transcallosal inhibition is greater in the ipsilesional than contralesional hemisphere and during dynamic than isometric tasks. Ipsilateral pathways and transcallosal inhibition may influence walking asymmetry and ankle movement accuracy.
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The modulation of short and long-latency interhemispheric inhibition during bimanually coordinated movements. Exp Brain Res 2021; 239:1507-1516. [PMID: 33687518 DOI: 10.1007/s00221-021-06074-z] [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: 12/08/2020] [Accepted: 02/25/2021] [Indexed: 10/22/2022]
Abstract
Bimanual coordination is essential for the performance of many everyday tasks. There are several types of bimanually coordinated movements, classified according to whether the arms are acting to achieve a single goal (cooperative) or separate goals (independent), and whether the arms are moving symmetrically or asymmetrically. Symmetric bimanual movements are thought to facilitate corticomotor excitability (CME), while asymmetric bimanual movements are thought to recruit interhemispheric inhibition to reduce functional coupling between the motor cortices. The influences of movement symmetry and goal conceptualisation on interhemispheric interactions have not been studied together, and not during bimanually active dynamic tasks. The present study used transcranial magnetic stimulation (TMS) to investigate the modulation of CME and short- and long-latency interhemispheric inhibition (SIHI and LIHI, respectively) during bimanually active dynamic tasks requiring different types of bimanual coordination. Twenty healthy right-handed adults performed four bimanual tasks in which they held a dumbbell in each hand (independent) or a custom device between both hands (cooperative) while rhythmically flexing and extending their wrists symmetrically or asymmetrically. Motor-evoked potentials were recorded from the right extensor carpi ulnaris. We found CME was greater during asymmetric tasks than symmetric tasks, and movement symmetry did not modulate SIHI or LIHI. There was no effect of goal conceptualisation nor any interaction with movement symmetry for CME, SIHI or LIHI. Based on these results, movement symmetry and goal conceptualisation may not modulate interhemispheric inhibition during dynamic bimanual tasks. These findings contradict prevailing thinking about the roles of CME and interhemispheric inhibition in bimanual coordination.
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Andrews JC, Sankar T, Stein RB, Roy FD. Characterizing the effect of low intensity transcranial magnetic stimulation on the soleus H-reflex at rest. Exp Brain Res 2020; 238:2725-2731. [PMID: 32955615 DOI: 10.1007/s00221-020-05879-8] [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: 03/02/2020] [Accepted: 07/08/2020] [Indexed: 11/30/2022]
Abstract
Modulation of a Hoffmann (H)-reflex following transcranial magnetic stimulation (TMS) has been used to assess the nature of signals transmitted from cortical centers to lower motor neurons. Further characterizing the recruitment and time-course of the TMS-induced effect onto the soleus H-reflex adds to the discussion of these pathways and may improve its utility in clinical studies. In 10 healthy controls, TMS was used to condition the soleus H-reflex using TMS intensities from 65 to 110% of the resting motor threshold (RMT). Early facilitation [- 5 to - 3 ms condition-test (C-T) interval] was evident when TMS was 110% of RMT (P < 0.05). By comparison, late facilitation (+ 10 to + 20 ms C-T interval) was several times larger and observed over a wider range of TMS intensities, including 65-110% of RMT. The early inhibition (- 3 to - 1 ms C-T interval) had a low TMS threshold and was elicited over a wide range of intensity from 65% to 95% of RMT (all P < 0.05). A second inhibitory phase was seen ~ 4 ms later (+ 1 to + 4 ms C-T intervals) and was only observed for a TMS intensity of 95% of RMT (P < 0.05). The present findings reaffirm that subthreshold TMS strongly modulates soleus motor neurons and demonstrates that distinct pathways can be selectively probed at discrete C-T intervals when using specific TMS intensities.
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Affiliation(s)
- Jennifer C Andrews
- Department of Surgery, University of Alberta Hospital, WMC 1C3.13, Edmonton, AB, T6G 2E1, Canada
| | - Tejas Sankar
- Division of Neurosurgery, University of Alberta, Edmonton, Canada
| | - Richard B Stein
- Department of Physiology, University of Alberta, Edmonton, Canada
| | - François D Roy
- Department of Surgery, University of Alberta Hospital, WMC 1C3.13, Edmonton, AB, T6G 2E1, Canada.
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Wiegel P, Leukel C. Training of a discrete motor skill in humans is accompanied by increased excitability of the fastest corticospinal connections at movement onset. J Physiol 2020; 598:3485-3500. [DOI: 10.1113/jp279879] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 05/21/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Patrick Wiegel
- Department of Sport Science University of Freiburg Freiburg 79117 Germany
- Bernstein Center Freiburg University of Freiburg Freiburg 79104 Germany
| | - Christian Leukel
- Department of Sport Science University of Freiburg Freiburg 79117 Germany
- Bernstein Center Freiburg University of Freiburg Freiburg 79104 Germany
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