Efficient and Reliable Characterization of the Corticospinal System Using Transcranial Magnetic Stimulation

Kukke, Sahana N.; Paine, Rainer W.; Chao, Chi‐Chao; Campos, Ana Carolina de; Hallett, Mark

doi:10.1097/wnp.0000000000000057

Cited by 64 publications

(65 citation statements)

References 25 publications

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“…MEPmax was calculated with a stimulus/response curve performed at the beginning of the experiment. We recorded eight MEPs for each stimulus intensity starting at 110% of rMT with incrementing steps of 10% rMT up to MEPmax (Kukke et al, 2014;Pitcher et al, 2015). In the current study, the TS Intensity required to elicit the MEPtarget at rest corresponded on average to 124% rMT 6 (range 112-150 %rMT).…”

Section: Adaptive Threshold-hunting Techniquementioning

confidence: 73%

Unravelling the modulation of intracortical inhibition during motor imagery: An adaptive threshold-hunting study

Neige

Rannaud-Monany

Stinear

et al. 2019

Preprint

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Motor imagery (MI) is the mental simulation of an action without any apparent muscular contraction. By means of transcranial magnetic stimulation, few studies revealed a decrease of short-interval intracortical inhibition (SICI) within the primary motor cortex. However, this decrease is ambiguous, as one would expect greater inhibition during MI to prevent overt motor output. The current study investigated the extent of SICI modulation during MI through a methodological and a conceptual reconsideration of i) the importance of parameters to assess SICI (Exp.1) and ii) the inhibitory process within the primary motor cortex as an inherent feature of MI (Exp.2). Participants performed two tasks: 1) rest and 2) imagery of isometric abduction of the right index finger. Using transcranial magnetic stimulation, motor evoked potentials were elicited in the right first dorsal interosseous muscle. An adaptive threshold-hunting paradigm was used, where the stimulus intensity required to maintain a fixed motor evoked potential amplitude was quantified.To test SICI, we conditioned the test stimulus with a conditioning stimulus (CS) of different intensities. Results revealed an Intensity by Task interaction showing that SICI decreased during MI as compared to rest only for the higher CS intensity (Exp.1). At the lowest CS intensities, a Task main effect revealed that SICI increased during MI (Exp.2). SICI modulation during MI depends critically on the CS intensity. By optimising CS intensity, we have shown that SICI circuits may increase during MI, revealing a potential mechanism to prevent the production of a movement while the motor system is activated.

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Section: Adaptive Threshold-hunting Techniquementioning

confidence: 73%

Unravelling the modulation of intracortical inhibition during motor imagery: An adaptive threshold-hunting study

Neige

Rannaud-Monany

Stinear

et al. 2019

Preprint

View full text Add to dashboard Cite

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“…This normalization helps to consider the well‐known interindividual variances in RMT. RC was assessed using the intensities of 130%, 140%, and 150% of the individual RMT 25. For the statistical analyses, we calculated the mean of 10 MEP per intensity.…”

Section: Methodsmentioning

confidence: 99%

Altered paired associative stimulation‐induced plasticity in NMDAR encephalitis

Volz

Finke

Harms

et al. 2016

Ann Clin Transl Neurol

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ObjectiveTo determine whether neurophysiological mechanisms indicating cortical excitability, long‐term potentiation (LTP)‐like plasticity, GABAergic and glutamatergic function are altered in patients with anti‐N‐methyl‐d‐aspartate receptor (NMDAR) encephalitis and whether they can be helpful as markers of diagnostic assessment, disease progression, and potentially therapy response.MethodsNeurophysiological characterizations of patients with NMDAR encephalitis (n = 34, mean age: 28 ± 11 years; 30 females) and age/gender‐matched healthy controls (n = 27, 28.5 ± 10 years; 25 females) were performed using transcranial magnetic stimulation‐derived protocols including resting motor threshold, recruitment curve, intracortical facilitation, short intracortical inhibition, and cortical silent period. Paired associative stimulation (PAS) was applied to assess LTP‐like mechanisms which are mediated through NMDAR. Moreover, resting state functional connectivity was determined using functional magnetic resonance imaging.Results PAS‐induced plasticity differed significantly between groups (P = 0.0056). Cortical excitability, as assessed via motor‐evoked potentials after PAS, decreased in patients, whereas it increased in controls indicating malfunctioning of NMDAR in encephalitis patients. Lower PAS‐induced plasticity significantly correlated with the modified Rankin Scale (mRS) (r = −0.41; P = 0.0031) and was correlated with lower functional connectivity within the motor network in NMDAR encephalitis patients (P < 0.001, uncorrected). Other neurophysiological parameters were not significantly different between groups. Follow‐up assessments were available in six patients and demonstrated parallel improvement of PAS‐induced plasticity and mRS.InterpretationAssessment of PAS‐induced plasticity may help to determine NMDAR dysfunction and disease severity in NMDAR encephalitis, and might even aid as a sensitive, noninvasive, and well‐tolerated “electrophysiological biomarker” to monitor therapy response in the future.Clinical Trial RegistrationClinicalTrials.gov: Identifier: NCT01865578

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“…Curve fitting of the Boltzmann equation was done using the Levenberg-Marquardt algorithm (Seber and Wild, 2003) in Matlab (nlinfit function, The MathWorks, Inc.). This method has been described previously (Kukke et al, 2014). The test stimulus (TS) was S 50 , or the stimulation intensity that produces an MEP equal to 50% of MEP max .…”

Section: Methodsmentioning

confidence: 99%

Probing the interaction of the ipsilateral posterior parietal cortex with the premotor cortex using a novel transcranial magnetic stimulation technique

Shields

Park

Srivanitchapoom

et al. 2016

Clinical Neurophysiology

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Objective Functional imaging studies have shown that control of planned movement involves a distributed network that involves the premotor (PMv) and posterior parietal cortices (PPC). Similarly, anatomical studies show that these regions are densely interconnected via white matter tracts. We therefore hypothesized that the PPC influence over the motor cortex is partly via a connection with the PMv. Methods Using a novel three-pulse ipsilateral transcranial magnetic stimulation technique, we preconditioned the PPC (80%RMT) at ISIs from 4–15ms prior to stimulating the PMv and M1 at ISIs of 4 and 6ms. Results As previously shown, PMv-M1 paired-pulse stimulation resulted in inhibition of the MEP (90% RMT, 4–6ms) and PPC-M1 paired-pulse stimulation resulted in facilitation of the MEP (90% RMT, 4–8ms). PPC-M1 paired-pulse stimulation at 80%RMT preconditioning had no effect on M1. PPC-PMv-M1 stimulation resulted in reversal of inhibition observed with PMv-M1 stimulation at ISIs ranging from 6–15ms. Conclusions The reversal of inhibition observed with PPC-PMv-M1 stimulation suggests that the parietal connection to the PMv plays a role in the modulation of M1. Significance This is the first study to stimulate three intrahemispheric regions in order to test a disynaptic connection with M1. The described network may be important in a variety of movement disorders.

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Efficient and Reliable Characterization of the Corticospinal System Using Transcranial Magnetic Stimulation

Cited by 64 publications

References 25 publications

Unravelling the modulation of intracortical inhibition during motor imagery: An adaptive threshold-hunting study

Unravelling the modulation of intracortical inhibition during motor imagery: An adaptive threshold-hunting study

Altered paired associative stimulation‐induced plasticity in NMDAR encephalitis

Probing the interaction of the ipsilateral posterior parietal cortex with the premotor cortex using a novel transcranial magnetic stimulation technique

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