Voluntary activation of knee extensor muscles with transcranial magnetic stimulation

2020 ◽  
Author(s):  
James Louis Nuzzo ◽  
David S. Kennedy ◽  
Harrison T. Finn ◽  
Janet Louise Taylor
Keyword(s):  
Electrical Stimulation ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Vastus Lateralis ◽  
Test Validity ◽  
Femoral Nerve ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Stimulation Of

We examined if transcranial magnetic stimulation (TMS) is a valid tool for assessment of voluntary activation of the knee extensors in healthy individuals. Maximal M-waves (Mmax) of vastus lateralis (VL) were evoked with electrical stimulation of femoral nerve (FNS); Mmax of medial hamstrings (HS) was evoked with electrical stimulation of sciatic nerve branches; motor evoked potentials (MEPs) of VL and HS were evoked with TMS; superimposed twitches (SIT) of knee extensors were evoked with FNS and TMS. In Study 1, TMS intensity (69% output(SD 5)) was optimized for MEP sizes, but guidelines for test validity could not be met. Agonist VL MEPs were too small (51.4% Mmax(SD 11.9); guideline ≥70% Mmax) and antagonist HS MEPs were too big (16.5% Mmax(SD 10.3); guideline <10% Mmax). Consequently, the TMS estimated resting twitch (99.1 N(SD 37.2)) and FNS resting twitch (142.4 N(SD 41.8)) were different. In Study 2, SITs at 90% maximal voluntary contraction (MVC) were similar between TMS (16.1 N(SD 10.3)) and FNS (20.9 N(SD 16.7)), when TMS intensity was optimized for this purpose, suggesting a procedure that combines TMS SITs with FNS resting twitches could be valid. In Study 3, which tested the TMS intensity (56% output(SD 18)) that evoked the largest SIT at 90%MVC, voluntary activation from TMS (87.3%(SD 7.1)) and FNS (84.5%(SD 7.6)) were different. In sum, the contemporary procedure for TMS-based voluntary activation of the knee extensors is invalid. A modified procedure improves validity, but only in individuals who meet rigorous inclusion criteria for SITs and MEPs.

scholarly journals Sham transcranial magnetic stimulation using electrical stimulation of the scalp

2009 ◽  
Vol 2 (3) ◽  
pp. 168-173 ◽  
Author(s):  
Mark S. Mennemeier ◽  
William J. Triggs ◽  
Kenneth C. Chelette ◽  
A.J. Woods ◽  
Timothy A. Kimbrell ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Stimulation Of

The effect of transcranial magnetic stimulation on the excitability of the motor neuron pools of the muscles of the lower extremities

2021 ◽  
Author(s):  
S.S. Ananiev ◽  
D.A. Pavlov ◽  
R.N. Yakupov ◽  
V.A. Golodnova ◽  
M.V. Balykin
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Lower Extremities ◽  
Transcutaneous Electrical Stimulation ◽  
Stimulation Of

The study was conducted on 22 healthy men aged 18-23 years. The primary motor cortex innervating the lower limb was stimulated with transcranial magnetic stimulation. Using transcutaneous electrical stimulation of the spinal cord, evoked motor responses of the muscles of the lower extremities were initiated when electrodes were applied cutaneous between the spinous processes in the Th11-Th12 projection. Research protocol: Determination of the thresholds of BMO of the muscles of the lower extremities during TESCS; determination of the BMO threshold of the TA muscle in TMS; determination of the thresholds of the BMO of the muscles of the lower extremities during TESCS against the background of 80% and 90% TMS. It was found that magnetic stimulation of the motor cortex of the brain leads to an increase in the excitability of the neural structures of the lumbar thickening of the spinal cord and an improvement in neuromuscular interactions. Key words: transcranial magnetic stimulation, transcutaneous electrical stimulation of the spinal cord, neural networks, excitability, neuromuscular interactions.

scholarly journals Menstrual cycle-associated modulations in neuromuscular function and fatigability of the knee extensors in eumenorrheic women

2019 ◽  
Vol 126 (6) ◽  
pp. 1701-1712 ◽  
Author(s):  
Paul Ansdell ◽  
Callum G. Brownstein ◽  
Jakob Škarabot ◽  
Kirsty M. Hicks ◽  
Davina C. M. Simoes ◽  
...  
Keyword(s):  
Oral Contraceptive ◽  
Transcranial Magnetic Stimulation ◽  
Menstrual Cycle ◽  
Magnetic Stimulation ◽  
Motor Nerve ◽  
Oral Contraceptive Pill ◽  
Intracortical Inhibition ◽  
Neuromuscular Function ◽  
Voluntary Activation ◽  
Knee Extensors

Sex hormone concentrations of eumenorrheic women typically fluctuate across the menstrual cycle and can affect neural function such that estrogen has neuroexcitatory effects, and progesterone induces inhibition. However, the effects of these changes on corticospinal and intracortical circuitry and the motor performance of the knee extensors are unknown. The present two-part investigation aimed to 1) determine the measurement error of an exercise task, transcranial magnetic stimulation (TMS)-, and motor nerve stimulation (MNS)-derived responses in women ingesting a monophasic oral contraceptive pill (hormonally-constant) and 2) investigate whether these measures were modulated by menstrual cycle phase (MCP), by examining them before and after an intermittent isometric fatiguing task (60% of maximal voluntary contraction, MVC) with the knee extensors until task failure in eumenorrheic women on days 2, 14, and 21 of the menstrual cycle. The repeatability of neuromuscular measures at baseline and fatigability ranged between moderate and excellent in women taking the oral contraceptive pill. MVC was not affected by MCP ( P = 0.790). Voluntary activation (MNS and TMS) peaked on day 14 ( P = 0.007 and 0.008, respectively). Whereas corticospinal excitability was unchanged, short-interval intracortical inhibition was greatest on day 21 compared with days 14 and 2 ( P < 0.001). Additionally, time to task failure was longer on day 21 than on both days 14 and 2 (24 and 36%, respectively, P = 0.030). The observed changes were larger than the associated measurement errors. These data demonstrate that neuromuscular function and fatigability of the knee extensors vary across the menstrual cycle and may influence exercise performance involving locomotor muscles. NEW & NOTEWORTHY The present two-part study first demonstrated the repeatability of transcranial magnetic stimulation- and electrical motor nerve stimulation-evoked variables in a hormonally constant female population. Subsequently, it was demonstrated that the eumenorrheic menstrual cycle affects neuromuscular function. Changing concentrations of neuroactive hormones corresponded to greater voluntary activation on day 14, greater intracortical inhibition on day 21, and lowest fatigability on day 21. These alterations of knee extensor neuromuscular function have implications for locomotor activities.

scholarly journals Effect of graded hypoxia on supraspinal contributions to fatigue with unilateral knee-extensor contractions

2010 ◽  
Vol 109 (6) ◽  
pp. 1842-1851 ◽  
Author(s):  
Stuart Goodall ◽  
Emma Z. Ross ◽  
Lee M. Romer
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Maximal Voluntary Contraction ◽  
Magnetic Stimulation ◽  
Voluntary Contraction ◽  
Corticospinal Excitability ◽  
Voluntary Activation ◽  
Severe Hypoxia ◽  
Knee Extensors ◽  
Moderate Hypoxia

Supraspinal fatigue, defined as an exercise-induced decline in force caused by suboptimal output from the motor cortex, accounts for over one-quarter of the force loss after fatiguing contractions of the knee extensors in normoxia. We tested the hypothesis that the relative contribution of supraspinal fatigue would be elevated with increasing severities of acute hypoxia. On separate days, 11 healthy men performed sets of intermittent, isometric, quadriceps contractions at 60% maximal voluntary contraction to task failure in normoxia (inspired O2 fraction/arterial O2 saturation = 0.21/98%), mild hypoxia (0.16/93%), moderate hypoxia (0.13/85%), and severe hypoxia (0.10/74%). Electrical stimulation of the femoral nerve was performed to assess neuromuscular transmission and contractile properties of muscle fibers. Transcranial magnetic stimulation was delivered to the motor cortex to quantify corticospinal excitability and voluntary activation. After 10 min of breathing the test gas, neuromuscular function and cortical voluntary activation prefatigue were unaffected in any condition. The fatigue protocol resulted in ∼30% declines in maximal voluntary contraction force in all conditions, despite differences in time-to-task failure (24.7 min in normoxia vs. 15.9 min in severe hypoxia, P < 0.05). Potentiated quadriceps twitch force declined in all conditions, but the decline in severe hypoxia was less than that in normoxia ( P < 0.05). Cortical voluntary activation also declined in all conditions, but the deficit in severe hypoxia exceeded that in normoxia ( P < 0.05). The additional central fatigue in severe hypoxia was not due to altered corticospinal excitability, as electromyographic responses to transcranial magnetic stimulation were unchanged. Results indicate that peripheral mechanisms of fatigue contribute relatively more to the reduction in force-generating capacity of the knee extensors following submaximal intermittent isometric contractions in normoxia and mild to moderate hypoxia, whereas supraspinal fatigue plays a greater role in severe hypoxia.

scholarly journals Changes in corticospinal excitability during reach adaptation in force fields

2013 ◽  
Vol 109 (1) ◽  
pp. 124-136 ◽  
Author(s):  
Jean-Jacques Orban de Xivry ◽  
Mohammad Ali Ahmadi-Pajouh ◽  
Michelle D. Harran ◽  
Yousef Salimpour ◽  
Reza Shadmehr
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Neural Basis ◽  
Key Factor ◽  
Gradual Group ◽  
Specific Increase ◽  
Stimulation Of

Both abrupt and gradually imposed perturbations produce adaptive changes in motor output, but the neural basis of adaptation may be distinct. Here, we measured the state of the primary motor cortex (M1) and the corticospinal network during adaptation by measuring motor-evoked potentials (MEPs) before reach onset using transcranial magnetic stimulation of M1. Subjects reached in a force field in a schedule in which the field was introduced either abruptly or gradually over many trials. In both groups, by end of the training, muscles that countered the perturbation in a given direction increased their activity during the reach (labeled as the on direction for each muscle). In the abrupt group, in the period before the reach toward the on direction, MEPs in these muscles also increased, suggesting a direction-specific increase in the excitability of the corticospinal network. However, in the gradual group, these MEP changes were missing. After training, there was a period of washout. The MEPs did not return to baseline. Rather, in the abrupt group, off direction MEPs increased to match on direction MEPs. Therefore, we observed changes in corticospinal excitability in the abrupt but not gradual condition. Abrupt training includes the repetition of motor commands, and repetition may be the key factor that produces this plasticity. Furthermore, washout did not return MEPs to baseline, suggesting that washout engaged a new network that masked but did not erase the effects of previous adaptation. Abrupt but not gradual training appears to induce changes in M1 and/or corticospinal networks.

scholarly journals Disrupted Central Inhibition after Transcranial Magnetic Stimulation of Motor Cortex in Schizophrenia with Long-Term Antipsychotic Treatment

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Aulikki Ahlgrén-Rimpiläinen ◽  
Hannu Lauerma ◽  
Seppo Kähkönen ◽  
Ilpo Rimpiläinen
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Single Pulse ◽  
Contralateral Side ◽  
Antipsychotic Treatment ◽  
Stimulation Of

Aims. Schizophrenia is a neuropsychiatric disorder associated with mental and motor disturbances. We aimed to investigate motor control, especially central silent period (CSP) in subjects with schizophrenia (n=11) on long-term antipsychotic treatment compared to healthy controls (n=9). Methods. Latency and duration of motor evoked potentials (MEPs) and CSPs were measured with the help of single pulse transcranial magnetic stimulation (TMS) and intramuscular electrodes. After stimulation of the dominant and nondominant motor cortex of abductor digiti minimi (ADM) and tibialis anterior (TA) muscle areas, respective responses were measured on the contralateral side. Results. MEPs did not differ significantly between the groups. Multiple CSPs were found predominantly in subjects with schizophrenia, which showed a higher number of CSPs in the dominant ADM and the longest summarized duration of CSPs in the nondominant ADM (P<0.05) compared to controls. Conclusions. There were multiple CSPs predominantly in the upper extremities and in the dominant body side in subjects with schizophrenia. Behind multiple CSPs may lie an impaired regulation of excitatory or inhibitory neurotransmitter systems in central motor pathways. Further research is needed to clarify the role of the intramuscular recording methods and the effect of antipsychotics on the results.

Magnetic and electrical stimulation of the auditory cortex for intractable tinnitus

2004 ◽  
Vol 100 (3) ◽  
pp. 560-564 ◽  
Author(s):  
Dirk De Ridder ◽  
Gert De Mulder ◽  
Vincent Walsh ◽  
Neil Muggleton ◽  
Stefan Sunaert ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Transcranial Magnetic Stimulation ◽  
Auditory Cortex ◽  
Magnetic Stimulation ◽  
Cortical Plasticity ◽  
Cortical Reorganization ◽  
Complete Suppression ◽  
Content Type ◽  
Fine Print ◽  
Stimulation Of

✓ Tinnitus is a distressing symptom that affects up to 15% of the population for whom no satisfactory treatment exists. The authors present a novel surgical approach for the treatment of intractable tinnitus, based on cortical stimulation of the auditory cortex. Tinnitus can be considered an auditory phantom phenomenon similar to deafferentation pain, which is observed in the somatosensory system. Tinnitus is accompanied by a change in the tonotopic map of the auditory cortex. Furthermore, there is a highly positive association between the subjective intensity of the tinnitus and the amount of shift in tinnitus frequency in the auditory cortex, that is, the amount of cortical reorganization. This cortical reorganization can be demonstrated by functional magnetic resonance (fMR) imaging. Transcranial magnetic stimulation (TMS) is a noninvasive method of activating or deactivating focal areas of the human brain. Linked to a navigation system that is guided by fMR images of the auditory system, TMS can suppress areas of cortical plasticity. If it is successful in suppressing a patient's tinnitus, this focal and temporary effect can be perpetualized by implanting a cortical electrode. A neuronavigation-based auditory fMR imaging-guided TMS session was performed in a patient who suffered from tinnitus due to a cochlear nerve lesion. Complete suppression of the tinnitus was obtained. At a later time an extradural electrode was implanted with the guidance of auditory fMR imaging navigation. Postoperatively, the patient's tinnitus disappeared and remains absent 10 months later. Focal extradural electrical stimulation of the primary auditory cortex at the area of cortical plasticity is capable of suppressing contralateral tinnitus completely. Transcranial magnetic stimulation may be an ideal method for noninvasive studies of surgical candidates in whom stimulating electrodes might be implanted for tinnitus suppression.

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