Measuring ipsilateral silent period: Effects of muscle contraction levels and quantification methods

Kuo, Yi-Ling; Dubuc, Tobin; Boufadel, Danielle F.; Fisher, Beth E.

doi:10.1016/j.brainres.2017.08.015

Cited by 30 publications

(30 citation statements)

References 47 publications

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“…As the iSP is complicated involving alpha motor neuronal dynamics, callosal transfer with multiple inhibitory internetworks (including spinal), and muscular control, determination of the exact mechanism driving the change is not possible in the current work. However, it is likely that cortical changes account for more of the change than changes in the periphery (muscle capacity/tone), as previous work has repeatedly shown that increased levels of exogenous stimulation alters silent period duration more so than increased motor load (Giovannelli et al, 2009 ; Kuo et al, 2017 ). Therefore, the silent period may be a reflection of an intrinsic cortical inhibitory framework that serves to regulate interhemispheric transfer.…”

Section: Discussionmentioning

confidence: 99%

“…The iSP is a complicated measurement that involves a number of cortical and descending spinal inhibitory connections. The silent period onset is typically ~38 ms after stimulation and can last anywhere from 10 to 70 ms depending on stimulation and level of muscle contraction (Giovannelli et al, 2009 ; Petitjean and Ko, 2013 ; Fleming and Newham, 2017 ; Kuo et al, 2017 ). The ipsilateral inhibition seen in the most commonly measured muscle, the first dorsal interosseous (FDI), certainly involves primary motor cortex (M1) callosal transfer, as degradation of the corpus callosum diminishes the measure (Meyer et al, 1995 ; Li et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

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Influences of 12-Week Physical Activity Interventions on TMS Measures of Cortical Network Inhibition and Upper Extremity Motor Performance in Older Adults—A Feasibility Study

McGregor

Crosson

Mammino

et al. 2018

Front. Aging Neurosci.

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Objective: Data from previous cross-sectional studies have shown that an increased level of physical fitness is associated with improved motor dexterity across the lifespan. In addition, physical fitness is positively associated with increased laterality of cortical function during unimanual tasks; indicating that sedentary aging is associated with a loss of interhemispheric inhibition affecting motor performance. The present study employed exercise interventions in previously sedentary older adults to compare motor dexterity and measure of interhemispheric inhibition using transcranial magnetic stimulation (TMS) after the interventions.Methods: Twenty-one community-dwelling, reportedly sedentary older adults were recruited, randomized and enrolled to a 12-week aerobic exercise group or a 12-week non-aerobic exercise balance condition. The aerobic condition was comprised of an interval-based cycling “spin” activity, while the non-aerobic “balance” exercise condition involved balance and stretching activities. Participants completed upper extremity dexterity batteries and estimates of VO2max in addition to undergoing single (ipsilateral silent period—iSP) and paired-pulse interhemispheric inhibition (ppIHI) in separate assessment sessions before and after study interventions. After each intervention during which heart rate was continuously recorded to measure exertion level (load), participants crossed over into the alternate arm of the study for an additional 12-week intervention period in an AB/BA design with no washout period.Results: After the interventions, regardless of intervention order, participants in the aerobic spin condition showed higher estimated VO2max levels after the 12-week intervention as compared to estimated VO2max in the non-aerobic balance intervention. After controlling for carryover effects due to the study design, participants in the spin condition showed longer iSP duration than the balance condition. Heart rate load was more strongly correlated with silent period duration after the Spin condition than estimated VO2.Conclusions: Aging-related changes in cortical inhibition may be influenced by 12-week physical activity interventions when assessed with the iSP. Although inhibitory signaling is mediates both ppIHI and iSP measures each TMS modality likely employs distinct inhibitory networks, potentially differentially affected by aging. Changes in inhibitory function after physical activity interventions may be associated with improved dexterity and motor control at least as evidence from this feasibility study show.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influences of 12-Week Physical Activity Interventions on TMS Measures of Cortical Network Inhibition and Upper Extremity Motor Performance in Older Adults—A Feasibility Study

McGregor

Crosson

Mammino

et al. 2018

Front. Aging Neurosci.

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“…Ipsilateral silent period and related EMG activity were recorded from the FDI of the left hand, following the delivery of 15 TMS pulses (150% RMT) to the ipsilateral hemisphere ( 111 ). Approximately 3 s before each pulse, participants were instructed to perform 100% of MVC of their left hand, by applying force with their index finger to the force transducer.…”

Section: Methodsmentioning

confidence: 99%

Interhemispheric Cortical Inhibition Is Reduced in Young Adults With Developmental Coordination Disorder

Fuelscher

Enticott

et al. 2018

Front. Neurol.

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IntroductionWhile the etiology of developmental coordination disorder (DCD) is yet to be established, brain-behavior modeling provides a cogent argument that neuropathology may subserve the motor difficulties typical of DCD. We argue that a number of the core behavioral features of the DCD profile (such as poor surround inhibition, compromised motor inhibition, and the presence of mirror movements) are consistent with difficulties regulating inhibition within the primary motor cortex (M1). This study aimed to be the first account of the integrity of cortical inhibition in motor cortices in DCD.MethodThe sample consisted of eight adults with DCD aged (18–30 years) and 10 aged matched neurotypical controls. Participants received a common battery of single and paired-pulse transcranial magnetic stimulation from which a series of neurophysiological measures classically used to measure intra- [e.g., short-interval cortical inhibition (SICI), long-interval cortical inhibition (LICI), and cortical silent period] and inter hemispheric [e.g., ipsilateral silent period (ISP)] cortical inhibition of the M1 at rest were recorded.ResultsWhile no group differences were observed for any measure of intrahemispheric cortical inhibition, individuals with DCD demonstrated significantly reduced interhemispheric cortical inhibition relative to controls, shown by consistently lower ISPratios.ConclusionOur findings are consistent with the view that regulation of cortical inhibition of M1 activity may be atypical in individuals with DCD, indicating differential GABAergic operation. This effect, however, appears to be select to cortical inhibition. Importantly, our data support the notion that reduced interhemispheric M1 cortical inhibition may at least partly explain commonly reported difficulties with bimanual motor control in DCD. The neurochemical implications and limitations of this evidence will be discussed.

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“…rMT was determined as the lowest TMS intensity required to elicit a 50 μV motor evoked potential at least 50% of the time (5 out of 10 trials) at each hotspot. IHI was quantified as the normalized ipsilateral silent period of APB and TA muscle activity following a TMS pulse (Kuo et al, 2017). Participants were instructed to activate each muscle to 50% of their maximal voluntary contraction as a TMS pulse was delivered to the ipsilateral hemisphere (intensity: 130% rMT for APB and 110% rMT for TA).…”

Section: Case Reportmentioning

confidence: 99%

Emotional detachment, gait ataxia, and cerebellar dysconnectivity associated with compound heterozygous mutations in the SPG7 gene

et al. 2020

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We report a patient with autism-like deficits in emotional connectedness, executive dysfunction, and ataxia beginning at age 39. He had compound heterozygous variants in SPG7 (A510V and 1552+1 G>T substitutions), mutation of which is classically associated with spastic paraparesis. Diffusion MRI demonstrated abnormalities in the cerebellar outflow tracts. Transcranial magnetic stimulation showed a prolonged cortical silent period representing exaggerated cortical inhibition, as previously described with pure cerebellar degeneration. The acquired cerebellar cognitive affective syndrome in association with specific anatomic and neurophysiological abnormalities in the cerebellum expand the spectrum of SPG7-related neurodegeneration and support a role for cerebellar output in socio-emotional behavior.

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Measuring ipsilateral silent period: Effects of muscle contraction levels and quantification methods

Cited by 30 publications

References 47 publications

Influences of 12-Week Physical Activity Interventions on TMS Measures of Cortical Network Inhibition and Upper Extremity Motor Performance in Older Adults—A Feasibility Study

Influences of 12-Week Physical Activity Interventions on TMS Measures of Cortical Network Inhibition and Upper Extremity Motor Performance in Older Adults—A Feasibility Study

Interhemispheric Cortical Inhibition Is Reduced in Young Adults With Developmental Coordination Disorder

Emotional detachment, gait ataxia, and cerebellar dysconnectivity associated with compound heterozygous mutations in the SPG7 gene

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