Age-dependent changes in physiological threshold asymmetries for the motor evoked potential and silent period following transcranial magnetic stimulation

Author(s):  
Kaoru Matsunaga ◽  
Takenori Uozumi ◽  
Sadatoshi Tsuji ◽  
Yoshiyuki Murai
2013 ◽  
Vol 91 (2) ◽  
pp. 187-189 ◽  
Author(s):  
Alexis R. Mauger ◽  
James G. Hopker

Acetaminophen (ACT) facilitates the inhibition of voltage-gated calcium and sodium currents, which may effect cortico-spinal excitability. Twelve subjects ingested acetaminophen or a placebo and underwent transcranial magnetic stimulation to assess the motor evoked potential (MEP), and cortical silent period (CSP). ACT significantly increased MEP response (P > 0.05) but had no effect on CSP (P > 0.05). This indicates that ACT increases MEP and should be controlled for in studies where these measures are of interest.


Author(s):  
Kerry R. Mills

Transcranial magnetic stimulation (TMS) has been exploited to advance knowledge of corticospinal physiology and, in a number of conditions, to aid diagnosis and quantify corticospinal abnormalities. The basic physics of magnetic stimulation is described along with the effects of stimulating coils with different dimensions and shape. The effects of single TMS pulses over motor cortex to cause a descending volley of D and I waves, and their effects on spinal motor neurons resulting in a motor evoked potential (MEP) are described. Guidelines for the safe use of TMS are given. Methods to estimate useful clinical measures of corticospinal function, such as threshold, MEP amplitude, central motor conduction time, silent period and input:output relation are given, as is the means to quantify corticospinal conduction using the triple stimulation technique. The clinical utility of TMS in neurodegenerations, central demyelinating diseases, stroke, spinal cord disease, movement disorders, and functional disorders is discussed.


Author(s):  
Donald L. Gilbert

This article discusses how transcranial magnetic stimulation (TMS) can be used to study the pathophysiological substrata of pediatric neurological and neurobehavioural disorders and to provide practical guidance for future research. It outlines the substantial challenges inherent in studying in vivo the neurobiology of pediatric neurobehavioural disorders, such as safety, quantitative versus categorical measures, and challenges in correlational studies. It discusses ways in which TMS generates quantitative measures that may function as endophenotypes for neurobehavioural disorders. Combining TMS with other modalities may also be informative. Single- and paired-pulse TMS is safe and well tolerated in children. The application of rigorous experimental designs and a combination of TMS with other research methods may increase the knowledge of pathophysiology and treatment of pediatric neurobehavioural disorders.


2017 ◽  
Vol 122 (6) ◽  
pp. 1504-1515 ◽  
Author(s):  
Robin Souron ◽  
Adrien Farabet ◽  
Léonard Féasson ◽  
Alain Belli ◽  
Guillaume Y. Millet ◽  
...  

The aim of this study was to evaluate the effects of an 8-wk local vibration training (LVT) program on functional and corticospinal properties of dorsiflexor muscles. Forty-four young subjects were allocated to a training (VIB, n = 22) or control (CON, n = 22) group. The VIB group performed twenty-four 1-h sessions (3 sessions/wk) of 100-Hz vibration applied to the right tibialis anterior. Both legs were tested in each group before training (PRE), after 4 (MID) and 8 (POST) wk of training, and 2 wk after training (POST2W). Maximal voluntary contraction (MVC) torque was assessed, and transcranial magnetic stimulation (TMS) was used to evaluate cortical voluntary activation (VATMS), motor evoked potential (MEP), cortical silent period (CSP), and input-output curve parameters. MVC was significantly increased for VIB at MID for right and left legs [+7.4% ( P = 0.001) and +6.2% ( P < 0.01), respectively] and remained significantly greater than PRE at POST [+12.0% ( P < 0.001) and +10.1% ( P < 0.001), respectively]. VATMS was significantly increased for right and left legs at MID [+4.4% ( P < 0.01) and +4.7% ( P < 0.01), respectively] and at POST [+4.9% ( P = 0.001) and +6.2% ( P = 0.001), respectively]. These parameters remained enhanced in both legs at POST2W. MEP and CSP recorded during MVC and input-output curve parameters did not change at any time point for either leg. Despite no changes in excitability or inhibition being observed, LVT seems to be a promising method to improve strength through an increase of maximal voluntary activation, i.e., neural adaptations. Local vibration may thus be further considered for clinical or aging populations. NEW & NOTEWORTHY The effects of a local vibration training program on cortical voluntary activation measured with transcranial magnetic stimulation were assessed for the first time in dorsiflexors, a functionally important muscle group. We observed that training increased maximal voluntary strength likely because of the strong and repeated activation of Ia spindle afferents during vibration training that led to changes in the cortico-motoneuronal pathway, as demonstrated by the increase in cortical voluntary activation.


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