A Comparison of Two Methods in Acquiring Stimulus–Response Curves with Transcranial Magnetic Stimulation

2013 ◽  
Vol 6 (3) ◽  
pp. 306-309 ◽  
Author(s):  
Alan J. Pearce ◽  
Ross A. Clark ◽  
Dawson J. Kidgell
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Response Curves ◽  
Stimulus Response

Silent period to transcranial magnetic stimulation: construction and properties of stimulus–response curves in healthy volunteers

2005 ◽  
Vol 163 (1) ◽  
pp. 21-31 ◽  
Author(s):  
V. K. Kimiskidis ◽  
S. Papagiannopoulos ◽  
K. Sotirakoglou ◽  
D. A. Kazis ◽  
A. Kazis ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Healthy Volunteers ◽  
Magnetic Stimulation ◽  
Silent Period ◽  
Response Curves ◽  
Stimulus Response

Reproducible Measurement of Human Motoneuron Excitability With Magnetic Stimulation of the Corticospinal Tract

2009 ◽  
Vol 102 (1) ◽  
pp. 606-613 ◽  
Author(s):  
Peter G. Martin ◽  
Anna L. Hudson ◽  
Simon C. Gandevia ◽  
Janet L. Taylor
Keyword(s):  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials ◽  
Compound Action Potential ◽  
Maximal Response ◽  
Response Curves ◽  
Stimulus Response ◽  
Maximal Output ◽  
Voluntary Contractions ◽  
Stimulation Of

It is difficult to test responses of human motoneurons in a controlled way or to make longitudinal assessments of adaptive changes at the motoneuron level. These studies assessed the reliability of responses produced by magnetic stimulation of the corticospinal tract. Cervicomedullary motor evoked potentials (CMEPs) were recorded in the first dorsal interosseus (FDI) on 2 separate days. On each day, four sets of stimuli were delivered at the maximal output of the stimulator, with the final two sets ≥10 min after the initial sets. Sets of stimuli were also delivered at different stimulus intensities to obtain stimulus-response curves. In addition, on the second day, responses at different stimulus intensities were evoked during weak voluntary contractions. Responses were normalized to the maximal muscle compound action potential ( Mmax). CMEPs evoked in the relaxed FDI were small, even when stimulus intensity was maximal (3.6 ± 2.5% Mmax) but much larger during a weak contraction (e.g., 26.2 ± 10.2% Mmax). CMEPs evoked in the relaxed muscle at the maximal output of the stimulator were highly reproducible both within (ICC = 0.83, session 1; ICC = 0.87, session 2) and between sessions (ICC = 0.87). ICCs for parameters of the input-output curves, which included measures of motor threshold, slope, and maximal response size, ranged between 0.87 and 0.62. These results suggest that responses to magnetic stimulation of the corticospinal tract can be assessed in relaxation and contraction and can be reliably obtained for longitudinal studies of motoneuronal excitability.

scholarly journals Physical activity modulates corticospinal excitability of the lower limb in young and old adults

2017 ◽  
Vol 123 (2) ◽  
pp. 364-374 ◽  
Author(s):  
Hamidollah Hassanlouei ◽  
Christopher W. Sundberg ◽  
Ashleigh E. Smith ◽  
Andrew Kuplic ◽  
Sandra K. Hunter
Keyword(s):  
Physical Activity ◽  
Nervous System ◽  
Lower Limb ◽  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Corticospinal Excitability ◽  
Response Curves ◽  
Old Adults ◽  
Stimulus Response ◽  
Optimal Health

Aging is associated with reduced neuromuscular function, which may be due in part to altered corticospinal excitability. Regular physical activity (PA) may ameliorate these age-related declines, but the influence of PA on corticospinal excitability is unknown. The purpose of this study was to determine the influence of age, sex, and PA on corticospinal excitability by comparing the stimulus-response curves of motor evoked potentials (MEP) in 28 young (22.4 ± 2.2 yr; 14 women and 14 men) and 50 old adults (70.2 ± 6.1 yr; 22 women and 28 men) who varied in activity levels. Transcranial magnetic stimulation was used to elicit MEPs in the active vastus lateralis muscle (10% maximal voluntary contraction) with 5% increments in stimulator intensity until the maximum MEP amplitude. Stimulus-response curves of MEP amplitudes were fit with a four-parameter sigmoidal curve and the maximal slope calculated (slopemax). Habitual PA was assessed with tri-axial accelerometry and participants categorized into either those meeting the recommended PA guidelines for optimal health benefits (>10,000 steps/day, high-PA; n = 21) or those not meeting the guidelines (<10,000 steps/day, low-PA; n = 41). The MEP amplitudes and slopemax were greater in the low-PA compared with the high-PA group ( P < 0.05). Neither age nor sex influenced the stimulus-response curve parameters ( P > 0.05), suggesting that habitual PA influenced the excitability of the corticospinal tract projecting to the lower limb similarly in both young and old adults. These findings provide evidence that achieving the recommended PA guidelines for optimal health may mediate its effects on the nervous system by decreasing corticospinal excitability. NEW & NOTEWORTHY Transcranial magnetic stimulation was used to determine whether achieving the recommended 10,000 steps/day for optimal health influenced the excitability of the corticospinal tract projecting to the knee extensor muscles. Irrespective of age and sex, individuals who achieved >10,000 steps/day had lower corticospinal excitability than those who performed <10,000 steps/day, possibly representing greater control of inhibitory and excitatory networks. Physical activity involving >10,000 steps/day may mediate its effects on the nervous system by decreasing corticospinal excitability.

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