scholarly journals The Impact of Glucose on Corticospinal and Intracortical Excitability

2019 ◽  
Vol 9 (12) ◽  
pp. 339 ◽  
Author(s):  
Stephen L. Toepp ◽  
Claudia V. Turco ◽  
Mitchell B. Locke ◽  
Chiara Nicolini ◽  
Roshni Ravi ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Controlled Study ◽  
Glucose Response ◽  
Afferent Inhibition ◽  
Intracortical Excitability ◽  
The Impact

Neurotransmission is highly dependent on the availability of glucose-derived energy, although it is unclear how glucose availability modulates corticospinal and intracortical excitability as assessed via transcranial magnetic stimulation (TMS). In this double-blinded placebo-controlled study, we tested the effect of acute glucose intake on motor-evoked potential (MEP) recruitment curves, short-interval intracortical inhibition (SICI), short-latency afferent inhibition (SAI) and long-latency afferent inhibition (LAI). Eighteen healthy males participated in four sessions. Session 1 involved acquisition of an individualized blood glucose response curve. This allowed measurements to be time-locked to an individualized glucose peak after consuming one of three drinks during the subsequent three sessions. Participants were administered a 300 mL concealed solution containing 75 g of glucose, sucralose, or water in separate sessions. Dependent measures were assessed at baseline and twice after drinking the solution. Secondary measures included blood glucose and mean arterial pressure. Corticospinal excitability and blood pressure increased following the drink across all treatments. No changes were observed in SICI, SAI or LAI. There was no rise in corticospinal excitability that was specific to the glucose drink, suggesting that acute changes in glucose levels do not necessarily alter TMS measures of corticospinal or intracortical excitability.

scholarly journals Age-related Differences in Corticomotor Excitability and Inhibitory Processes during a Visuomotor RT Task

2012 ◽  
Vol 24 (5) ◽  
pp. 1253-1263 ◽  
Author(s):  
Hakuei Fujiyama ◽  
Mark R. Hinder ◽  
Matthew W. Schmidt ◽  
Christophe Tandonnet ◽  
Michael I. Garry ◽  
...  
Keyword(s):  
Older Adults ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Response Preparation ◽  
Younger Adults ◽  
Inhibitory Processes ◽  
Age Related ◽  
The Right

This study tested the postulation that change in the ability to modulate corticospinal excitability and inhibitory processes underlie age-related differences in response preparation and generation during tasks requiring either rapid execution of a motor action or actively withholding that same action. Younger (n = 13, mean age = 26.0 years) and older adults (n = 13, mean age = 65.5 years) performed an RT task in which a warning signal (WS) was followed by an imperative signal (IS) to which participants were required to respond with a rapid flexion of the right thumb (go condition) or withhold their response (no-go condition). We explored the neural correlates of response preparation, generation, and inhibition using single- and paired-pulse TMS, which was administered at various times between WS and IS (response preparation phase) and between IS and onset of response-related muscle activity in the right thumb (response generation phase). Both groups exhibited increases in motor-evoked potential amplitudes (relative to WS onset) during response generation; however, this increase began earlier and was more pronounced for the younger adults in the go condition. Moreover, younger adults showed a general decrease in short-interval intracortical inhibition during response preparation in both the go and no-go conditions, which was not observed in older adults. Importantly, correlation analysis suggested that for older adults the task-related increases of corticospinal excitability and intracortical inhibition were associated with faster RT. We propose that the declined ability to functionally modulate corticospinal activity with advancing age may underlie response slowing in older adults.

scholarly journals Neurophysiological adaptations in the untrained side in conjunction with cross-education of muscle strength: a systematic review and meta-analysis

2018 ◽  
Vol 124 (6) ◽  
pp. 1502-1518 ◽  
Author(s):  
Andrea Manca ◽  
Tibor Hortobágyi ◽  
John Rothwell ◽  
Franca Deriu
Keyword(s):  
Meta Analysis ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Intracortical Inhibition ◽  
Body Region ◽  
Future Research ◽  
Afferent Inhibition ◽  
Cross Education ◽  
V Wave

We reviewed the evidence from randomized controlled trials (RCTs) focusing on the neurophysiological adaptations in the untrained side associated with cross-education of strength (CE) and pooled data into definite effect estimates for neurophysiological variables assessed in chronic CE studies. Furthermore, scoping directions for future research were provided to enhance the homogeneity and comparability of studies investigating the neural responses to CE. The magnitude of CE was 21.1 ± 18.2% (mean ± SD; P < 0.0001) in 22 RCTs ( n = 467 subjects) that measured at least 1 neurophysiological variable in the untrained side, including the following: electromyography (EMG; 14 studies); motor evoked potential (MEP; 8 studies); short-interval intracortical inhibition (SICI), recruitment curve, and M wave (6 studies); cortical silent period (cSP; 5 studies); interhemispheric inhibition, intracortical facilitation (ICF), and H reflex (2 studies); and V wave, short-interval ICF, short-latency afferent inhibition, and long-latency afferent inhibition (1 study). Only EMG, MEP, ICF, cSP, and SICI could be included in the meta-analysis (18 studies, n = 387). EMG ( P = 0.26, n = 235) and MEP amplitude ( P = 0.11, n = 145) did not change in the untrained limb after CE. cSP duration ( P = 0.02, n = 114) and SICI ( P = 0.001, n = 95) decreased in the untrained hemisphere according to body region and type and intensity of training. The magnitude of CE did not correlate with changes in these transcranial magnetic stimulation (TMS) measures. The design of this meta-analytical study and the lack of correlations prevented the ability to link mechanistically the observed neurophysiological changes to CE. Notwithstanding the limited amount of data available for pooling, the use of TMS to assess the ipsilateral neurophysiological responses to unilateral training still confirms the central neural origin hypothesis of chronic CE induced by strength training. However, how these neural adaptations contribute to CE remains unclear.

Effects of water immersion on short- and long-latency afferent inhibition, short-interval intracortical inhibition, and intracortical facilitation

2013 ◽  
Vol 124 (9) ◽  
pp. 1846-1852 ◽  
Author(s):  
Daisuke Sato ◽  
Koya Yamashiro ◽  
Takuya Yoshida ◽  
Hideaki Onishi ◽  
Yoshimitsu Shimoyama ◽  
...  
Keyword(s):  
Water Immersion ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Intracortical Facilitation ◽  
Afferent Inhibition ◽  
Long Latency

scholarly journals Influence of Voluntary Contraction Level, Test Stimulus Intensity and Normalization Procedures on the Evaluation of Short-Interval Intracortical Inhibition

2020 ◽  
Vol 10 (7) ◽  
pp. 433
Author(s):  
Cécilia Neige ◽  
Sidney Grosprêtre ◽  
Alain Martin ◽  
Florent Lebon
Keyword(s):  
Healthy Subjects ◽  
Compound Muscle Action Potential ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Voluntary Contraction ◽  
Experimental Conditions ◽  
Specific Level ◽  
M Wave ◽  
Spinal Motoneurones

Short-interval intracortical inhibition (SICI) represents an inhibitory phenomenon acting at the cortical level. However, SICI estimation is based on the amplitude of a motor-evoked potential (MEP), which depends on the discharge of spinal motoneurones and the generation of compound muscle action potential (M-wave). In this study, we underpin the importance of taking into account the proportion of spinal motoneurones that are activated or not when investigating the SICI of the right flexor carpi radialis (normalization with maximal M-wave (Mmax) and MEPtest, respectively), in 15 healthy subjects. We probed SICI changes according to various MEPtest amplitudes that were modulated actively (four levels of muscle contraction: rest, 10%, 20% and 30% of maximal voluntary contraction (MVC)) and passively (two intensities of test transcranial magnetic stimulation (TMS): 120 and 130% of motor thresholds). When normalized to MEPtest, SICI remained unchanged by stimulation intensity and only decreased at 30% of MVC when compared with rest. However, when normalized to Mmax, we provided the first evidence of a strong individual relationship between SICI and MEPtest, which was ultimately independent from experimental conditions (muscle states and TMS intensities). Under similar experimental conditions, it is thus possible to predict SICI individually from a specific level of corticospinal excitability in healthy subjects.

scholarly journals High-Volume Light-Load Strength Training, but Not Low-Volume Heavy-Load Strength Training Increases Corticospinal Excitability

2020 ◽  
Vol 2 (3) ◽  
pp. 1-12
Author(s):  
Rhys Painter ◽  
Simin Rahman ◽  
Woo Kim ◽  
Ummatul Siddique ◽  
Ashlyn Frazer ◽  
...  
Keyword(s):  
Strength Training ◽  
Short Interval ◽  
High Volume ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Control Group ◽  
Heavy Load ◽  
Post Exercise ◽  
Light Load ◽  
Low Volume

Purpose: To determine whether corticospinal excitability (CSE) and inhibition are differentially modulated following high-volume light-load strength training compared to low-volume heavy-load strength training. We hypothesised high-volume light-load strength training would increase CSE and low-volume heavy-load strength training would reduce intracortical inhibition. Methods: Transcranial magnetic stimulation (TMS) was used to assess CSE, short-interval intracortical inhibition (SICI), and silent period duration (SP) following high-volume light-load strength training (n = 9), low-volume heavy-load strength training (n = 8) compared to a control group (n = 10). Twenty-seven participants completed either (1) low-volume heavy-load strength training (80% one-repetition maximum [1RM]); (2) high-volume light-load strength training (20% 1-RM) or (3) a control condition. CSE, SICI and SP were measured using TMS at baseline and four time-points over a 60 min post-exercise period. Results: CSE increased rapidly (within 5 min post-exercise) for high-volume light-load strength training and remained elevated for 60 min compared to low-volume heavy-load strength training and control groups. There were no differences following any training for reduced SICI or SP. Conclusion: These results suggest that high-volume light-load strength training increases the excitability of corticospinal neurons and this increase is likely to be the predominant mechanism for increasing CSE for up to 60 min post training. It may be possible that a greater number of ST sessions are required to observe any differences in the excitability of the intrinsic inhibitory motor-network following high-volume light-load strength training and low-volume heavy-load strength training.

Changes in Cortical Excitability and Parkinson Tremor After Botulinum Toxin Therapy

Neurology ◽  
2021 ◽  
Vol 97 (14) ◽  
pp. e1413-e1424
Author(s):  
Olivia Samotus ◽  
Robert Chen ◽  
Mandar Jog
Keyword(s):  
Botulinum Toxin ◽  
De Novo ◽  
Cortical Excitability ◽  
Botulinum Toxin Type A ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Botulinum Toxin Type ◽  
Intracortical Inhibition ◽  
Botulinum Toxin Therapy ◽  
Time Point

Background and ObjectivesTo investigate the relationship between botulinum toxin type A (BoNT-A) administration, tremor amplitude, and modulation of intracortical excitability and sensorimotor processing using paired-pulse transcranial magnetic stimulation (pp-TMS) in patients with early, tremor-dominant Parkinson disease (PD).MethodsTwelve de novo (naive to anti-PD medications) and 7 l-dopa (optimized on levodopa) participants with PD with tremor affecting one arm were recruited. All participants received 4 serial BoNT-A treatments for tremor every 12 weeks and peak effect was assessed 6 weeks posttreatment, totaling 8 visits over 42 weeks. Injection measures were based on kinematic tremor analysis. Short interval intracortical inhibition (SICI), intracortical facilitation (ICF), long interval intracortical inhibition (LICI), and measures of sensorimotor interaction (short-latency afferent [SAI] and long-latency afferent [LAI] stimulation) were assessed in both hemispheres using pp-TMS paradigms at each time point. Linear mixed models analyzed the effect of each pp-TMS measure and tremor severity within each cohort and the association between pp-TMS and tremor severity in the de novo cohort over 42 weeks. t Tests compared pp-TMS measures between hemispheres per time point.ResultsBaseline SICI, LICI, and SAI was reduced (higher motor evoked potential [MEP] ratio) on the tremulous/treated side compared to the nontremulous side in de novo participants. On the treated side in the de novo cohort, BoNT-A treatment significantly reduced ICF and increased LICI, SAI, and LAI (lower MEP ratio) at peak BoNT-A time points. The change in tremor severity was significantly associated with changes in SICI, LICI, and LAI.DiscussionOur findings suggest that tremor severity in early PD may be related to impaired intracortical inhibition and defective sensorimotor integration.

Cortical dysfunction underlies disability in multiple sclerosis

2011 ◽  
Vol 18 (4) ◽  
pp. 425-432 ◽  
Author(s):  
Steve Vucic ◽  
Therese Burke ◽  
Kerry Lenton ◽  
Sudarshini Ramanathan ◽  
Lavier Gomes ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Cortical Excitability ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Progressive Multiple Sclerosis ◽  
Conduction Time ◽  
Cortical Function ◽  
Resting Motor Threshold ◽  
Cortical Dysfunction

Background: Gray matter atrophy has been implicated in the development of secondary progressive multiple sclerosis (SPMS). Cortical function may be assessed by transcranial magnetic stimulation (TMS). Determining whether cortical dysfunction was a feature of SPMS could be of pathophysiological significance. Objectives: Consequently, novel paired-pulse threshold tracking TMS techniques were used to assess whether cortical dysfunction was a feature of SPMS. Methods: Cortical excitability studies were undertaken in 15 SPMS, 25 relapsing–remitting MS patients (RRMS) and 66 controls. Results: Short interval intracortical inhibition (SPMS 3.0 ± 2.1%; RRMS 12.8 ± 1.7%, p < 0.01; controls 10.5 ± 0.7%, p < 0.01) and motor evoked potential (MEP) amplitude (SPMS 11.5 ± 2.2%; RRMS 26.3 ± 3.6%, p <0.05; controls 24.7 ± 1.8%, p < 0.01) were reduced in SPMS, while intracortical facilitation (SPMS -5.2 ± 1.9%; RRMS -2.0 ± 1.4, p < 0.05; controls -0.9 ± 0.7, p < 0.01) and resting motor threshold were increased (SPMS 67.5 ± 4.5%; RRMS 56.0 ± 1.5%, p < 0.01; controls 59.0 ± 1.1%, p < 0.001). Further, central motor conduction time was prolonged in SPMS (9.1 ± 1.2 ms, p < 0.001) and RRMS (7.0 ± 0.9 ms, p < 0.05) patients compared with controls (5.5 ± 0.2 ms). The observed changes in cortical function correlated with the Expanded Disability Status Scale. Conclusion: Together, these findings suggest that cortical dysfunction is associated with disability in MS, and documentation of such cortical dysfunction may serve to quantify disease severity in MS.

scholarly journals The Acute Impact of Ingestion of Sourdough and Whole-Grain Breads on Blood Glucose, Insulin, and Incretins in Overweight and Obese Men

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Anita Mofidi ◽  
Zachary M. Ferraro ◽  
Katherine A. Stewart ◽  
Hilary M. F. Tulk ◽  
Lindsay E. Robinson ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Glucose Homeostasis ◽  
Area Under The Curve ◽  
Glycemic Response ◽  
Whole Grain ◽  
Glucose Response ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Impact ◽  
Randomized Crossover Study

Consumption of whole-grain and sourdough breads is associated with improved glucose homeostasis. We examined the impact of commercial breads on biomarkers of glucose homeostasis in subjects at risk for glucose intolerance. In a randomized, crossover study, overweight or obese males ingested 11-grain, sprouted-grain, 12-grain, sourdough, or white bread on different occasions, matched for available carbohydrate (50 g) in part 1 (n=12) and bread mass (107 g) in part 2 (n=11), and blood glucose, insulin and glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) were determined for 3 h. In part 1, glucose response for sprouted-grain was lower than 11-grain, sourdough, and white breads. Insulin area under the curve (AUC) for sourdough and white was lower than 11-grain and sprouted-grain breads. GLP-1 response to sourdough was lower than all breads. In part 2, glucose and insulin AUC for sourdough was greater than 11-grain, sprouted-grain, and 12-grain breads. Sprouted-grain bread improved glycemia by lowering glucose response and increasing GLP-1 response. In overweight and obese men, the glycemic response to sprouted grain bread was reduced in both parts 1 and 2 while the other whole-grain test breads did not improve metabolic responses in the acute postprandial state.

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