OBJECTIVE: Intracortical excitability was studied for 4 muscles in the upper extremity by paired transcranial magnetic stimulation on the motor cortex, using focal and non-focal coils. METHODS: Surface EMG responses of two hand and two forearm muscles were simultaneously recorded in 13 healthy subjects, after delivering paired stimuli at interstimulus intervals (ISIs) of 1-50 ms using circular and figure-of-8 (focal) coils. The intensities of conditioning and test stimuli were submotor and supramotor thresholds, respectively. RESULTS: Paired stimulation using a circular coil showed constant inhibition at 2 ms ISI for all muscles, but not at 5 ms ISI, and induced facilitation at 10 ms ISI. The results using a focal coil were similar to those with a circular coil at all ISIs except at 5 ms ISI, where the former showed inhibition. At 20 and 30 ms ISIs, there was interindividual variability for both coils, some subjects showing inhibition and others facilitation. CONCLUSIONS: The difference of the inhibition at 5 ms ISI between using circular and focal coils could be attributed to the cortical mechanism. The inhibitory effect at 2 ms ISI, consistently observed for the 4 muscles with both types of coil, could be easily applied to assess the inhibitory intracortical function in patients with neurological diseases.
OBJECTIVE: Intracortical excitability was studied for 4 muscles in the upper extremity by paired transcranial magnetic stimulation on the motor cortex, using focal and non-focal coils. METHODS: Surface EMG responses of two hand and two forearm muscles were simultaneously recorded in 13 healthy subjects, after delivering paired stimuli at interstimulus intervals (ISIs) of 1-50 ms using circular and figure-of-8 (focal) coils. The intensities of conditioning and test stimuli were submotor and supramotor thresholds, respectively. RESULTS: Paired stimulation using a circular coil showed constant inhibition at 2 ms ISI for all muscles, but not at 5 ms ISI, and induced facilitation at 10 ms ISI. The results using a focal coil were similar to those with a circular coil at all ISIs except at 5 ms ISI, where the former showed inhibition. At 20 and 30 ms ISIs, there was interindividual variability for both coils, some subjects showing inhibition and others facilitation. CONCLUSIONS: The difference of the inhibition at 5 ms ISI between using circular and focal coils could be attributed to the cortical mechanism. The inhibitory effect at 2 ms ISI, consistently observed for the 4 muscles with both types of coil, could be easily applied to assess the inhibitory intracortical function in patients with neurological diseases.
Authors: M Oliveri; C Caltagirone; M M Filippi; R Traversa; P Cicinelli; P Pasqualetti; P M Rossini Journal: J Physiol Date: 2000-12-01 Impact factor: 5.182
Authors: Prisca R Bauer; Annika A de Goede; William M Stern; Adam D Pawley; Fahmida A Chowdhury; Robert M Helling; Romain Bouet; Stiliyan N Kalitzin; Gerhard H Visser; Sanjay M Sisodiya; John C Rothwell; Mark P Richardson; Michel J A M van Putten; Josemir W Sander Journal: Brain Date: 2018-02-01 Impact factor: 13.501
Authors: Xue Zhang; Daniel G Woolley; Stephan P Swinnen; Hilde Feys; Raf Meesen; Nicole Wenderoth Journal: PLoS One Date: 2014-07-07 Impact factor: 3.240