Short-interval intracortical inhibition and facilitation targeting upper and lower limb muscles

Mrachacz-Kersting, Natalie; Stevenson, Andrew James Thomas; Ziemann, Ulf

doi:10.1038/s41598-021-01348-6

Cited by 8 publications

(5 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, our corticospinal excitability data were not normalized to the maximum compound action potential (M-max). Normalization of TMS-derived MEPs has been common in TMS lower-limb studies as a means of reducing variability (4,14), although not all investigations have performed so (22). Our primary rationale for the lack of normalization was due to time constraints, as well as our group's inexperience with nerve stimulation of the biceps femoris, a composite muscle innervated by both the common fibular branch and the tibial branch of the sciatic nerve.…”

Section: Discussionmentioning

confidence: 99%

Sex-Specific Reliability of Lower-Limb Corticospinal Excitability and Silent Periods

Pagan,

Harmon,

Girts

et al. 2023

Journal of Strength and Conditioning Research

View full text Add to dashboard Cite

2023-Transcranial magnetic stimulation (TMS) is a research tool that has potential to provide new insights into strength traininginduced adaptations. However, using TMS to study the lower limbs is challenging, and sex-specific reliability has yet to be reported. We examined the reliability of corticospinal excitability and silent periods for the rectus femoris, vastus lateralis, and biceps femoris in both sexes. Thirteen males and 14 females reported to the laboratory twice. During both trials, a double cone coil was used to deliver 20 pulses to the rectus femoris hotspot with a stimulator output of 130% of active motor threshold. Motor-evoked potential peak-to-peak amplitude, which reflects corticospinal excitability, and silent period duration were quantified. Our results offer 4 novel findings. First, corticospinal excitability and silent period demonstrated higher reliability for the females. Second, regardless of sex and muscle, the silent period was more reliable than corticospinal excitability. Third, reliability was highest for our target muscle (rectus femoris), with lower reliability for the vastus lateralis and biceps femoris, suggesting that these methods cannot be used to study coactivation. Fourth, active motor threshold showed less variability than corticospinal excitability and silent period but increased at trial 2 in females. Many of the intraclass correlation coefficients were excellent ($0.90), although we attribute this finding to variability between subjects. Reliability of lower-limb TMS measures may be sex, muscle, and variable dependent. Our findings suggest that both males and females should be included in lower-limb TMS research, although combining data between sexes should be approached cautiously.

show abstract

Section: Discussionmentioning

confidence: 99%

Sex-Specific Reliability of Lower-Limb Corticospinal Excitability and Silent Periods

Pagan,

Harmon,

Girts

et al. 2023

Journal of Strength and Conditioning Research

View full text Add to dashboard Cite

show abstract

“…Short interval intracortical inhibition (SICI), measured by paired pulse TMS, is a biomarker of inhibitory GABAergic intracortical circuits located within the primary motor cortex [64,65]. Numerous studies have established the presence of decreased SICI in sporadic and familial ALS cohorts, suggesting dysfunction of GABA A inhibitory neurons within the motor cortex [66][67][68].…”

Section: Neurophysiological Evidencementioning

confidence: 99%

“…Other features that support the advent of cortical hyperexcitability include intracortical facilitation (ICF), which is mediated by I waves, which originate at the cortical level through synaptic input from excitatory interneuronal circuitries onto corticomotoneuronal cells [64]. Increased ICF, suggesting increased intracortical excitability, is a typical finding in ALS [71], while somatosensory evoked potentials (SEP) also exhibited increased amplitudes [72,73], with sensory hyperexcitability associated with shorter survival [72].…”

Section: Neurophysiological Evidencementioning

confidence: 99%

Neuronal Hyperexcitability and Free Radical Toxicity in Amyotrophic Lateral Sclerosis: Established and Future Targets

et al. 2022

View full text Add to dashboard Cite

Amyotrophic lateral sclerosis (ALS) is a devastating disease with evidence of degeneration involving upper and lower motor neuron compartments of the nervous system. Presently, two drugs, riluzole and edaravone, have been established as being useful in slowing disease progression in ALS. Riluzole possesses anti-glutamatergic properties, while edaravone eliminates free radicals (FRs). Glutamate is the excitatory neurotransmitter in the brain and spinal cord and binds to several inotropic receptors. Excessive activation of these receptors generates FRs, inducing neurodegeneration via damage to intracellular organelles and upregulation of proinflammatory mediators. FRs bind to intracellular structures, leading to cellular impairment that contributes to neurodegeneration. As such, excitotoxicity and FR toxicities have been considered as key pathophysiological mechanisms that contribute to the cascade of degeneration that envelopes neurons in ALS. Recent advanced technologies, including neurophysiological, imaging, pathological and biochemical techniques, have concurrently identified evidence of increased excitability in ALS. This review focuses on the relationship between FRs and excitotoxicity in motor neuronal degeneration in ALS and introduces concepts linked to increased excitability across both compartments of the human nervous system. Within this cellular framework, future strategies to promote therapeutic development in ALS, from the perspective of neuronal excitability and function, will be critically appraised.

show abstract

“…6,10–12 Once the motor threshold is determined, subsequent stimulation intensities are normalized to this value to measure key cortical and corticospinal characteristics such as excitability, facilitation, and inhibition. 13,14…”

Section: Introductionmentioning

confidence: 99%

“…6,[10][11][12] Once the motor threshold is determined, subsequent stimulation intensities are normalized to this value to measure key cortical and corticospinal characteristics such as excitability, facilitation, and inhibition. 13,14 To our knowledge, Rossini et al were among the first to propose a standardize paradigm to estimate motor thresholds in resting and active muscles. 7,15 Within their active motor thresholding criteria recommendations, they proposed to define a "positive" motor responses to stimulation as absolute MEP values of ≥ 200µV (active motor threshold [AMT]).…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Techniques to Determine Active Motor Threshold for Transcranial Magnetic Stimulation Research

Beausejour,

Rusch,

Knowles

et al. 2024

Preprint

View full text Add to dashboard Cite

The determination of active motor threshold (AMT) is a critical step in transcranial magnetic stimulation (TMS) research protocols involving voluntary muscle contractions. As AMT is frequently determined using an absolute electromyographic (EMG) threshold (e.g., 200 microvolts peak-to-peak amplitude), wide variation in EMG recordings across participants has given reason to consider a relative threshold (e.g., = 2x background EMG) for AMT determination. However, these approaches have never been systemically compared. PURPOSE: We sought to compare the AMT values derived from absolute and relative criteria commonly used to determine AMT in the quadriceps muscles, and assess the test-retest reliability of each approach (absolute = 200 microvolts vs. relative = 2x background EMG). METHODS: Eighteen young adults (9 males and 9 females; mean +/- SD age = 23 +/- 2 years) visited the research laboratory on two occasions. All testing was conducted on the dominant limb. During each laboratory visit, maximal voluntary isometric contraction (MVIC) quadriceps torque was measured, with all subsequent TMS procedures conducted as participants maintained 10% of MVIC torque. AMT values were derived from each criterion using motor evoked potentials recorded from the vastus lateralis (VL) and defined as the lowest stimulator output (SO%) needed to meet the specified criteria within at least 5/10 pulses. The order of criteria (i.e., absolute vs. relative) was randomized during the first laboratory visit, and counterbalanced during the second visit. A paired samples t-test, 95% confidence intervals and the effect size were used to compare mean differences in AMT values obtained from each criterion during the second laboratory visit. Paired samples t-tests, intraclass correlation coefficients (ICC2,1), standard errors of measurement (SEMs), and the minimal difference (MD) scores were calculated to assess test-retest reliability of each AMT criterion. RESULTS: Differences between the AMT criteria were small and not statistically significant (absolute criterion mean = 48.9%, relative criterion mean = 47.4%; p = .309, Cohens d = 0.247). The absolute criterion demonstrated moderate to excellent reliability (ICC2,1= .866 [0.648 , 0.950], SEM = 7.9%, MD = 10.4%), but higher AMTs were observed in the second visit compared to the first (p = 0.043). The relative criteria demonstrated good-to-excellent test-retest reliability (ICC2,1= .894 [0.746 , 0.959], SEM = 6.9%, MD = 8.9%) and AMTs were not different between visits (p = 0.420). CONCLUSION: Quantifying AMT with an absolute voltage threshold of 200 microvolts peak-to-peak amplitude and a relative voltage threshold 2x background EMG resulted in similar values within a single testing session. However, the relative voltage criterion demonstrated superior test-rest reliability. TMS researchers aiming to track cortical or corticospinal characteristics across visits should consider implementing relative criterion approaches during their AMT determination protocol.

show abstract

Short-interval intracortical inhibition and facilitation targeting upper and lower limb muscles

Cited by 8 publications

References 36 publications

Sex-Specific Reliability of Lower-Limb Corticospinal Excitability and Silent Periods

Sex-Specific Reliability of Lower-Limb Corticospinal Excitability and Silent Periods

Neuronal Hyperexcitability and Free Radical Toxicity in Amyotrophic Lateral Sclerosis: Established and Future Targets

A Comparison of Techniques to Determine Active Motor Threshold for Transcranial Magnetic Stimulation Research

Contact Info

Product

Resources

About