Poster (Scientific congresses and symposiums)
Preserved automatic inhibition effect after 1 Hz repetitive transcranial magnetic stimulation over the supplementary motor area
D'Ostilio, Kevin; CREMERS, Julien; DELVAUX, Valérie et al.
20135 th International Conference on non-Invasive Brain stimulation
 

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Abstract :
[en] Background: It is widely accepted that medial frontal regions are involved in voluntary action control. Indeed, Sumner et al. (2007) have recently suggested that one of the mechanisms through which the supplementary motor area (SMA) contributes to voluntary control is automatic and unconscious motor inhibition. In this study, they administered a visuo-motor subliminal masked prime task (Eimer & Schlaghecken, 2003) to two patients with micro-lesions of the SMA and demonstrated an absence of automatic and unconscious inhibition as evoked by masked prime stimuli. This finding has been supported by neuroimaging data (D'Ostilio et al., 2012). Here, the aim of our research was to corroborate this result by means of a “virtual lesion” approach. Methods: For this purpose, we examined the effects of 1 Hz rTMS (train of 20 min; stimulus intensity 120 % of resting motor threshold) over the SMA of ten healthy volunteers, previously localized by functional magnetic resonance imaging (fMRI), on reaction time (RT) performance in the subliminal masked prime task. The functional localizer experiment consisted of four blocks of sequential finger tapping and 15 s of rest after each block. Imaging data were analyzed with SPM 8 and then were imported into the Brainsight software version 2.1.5. With such system, we were able to navigate across the subjects’ brain. The peak voxel in the SMA for each subject (at a statistical threshold of p < 0.05 uncorrected) was used as a target point for the rTMS session. Results: The mean motor threshold was 50.9 % of maximal stimulator output (SD: ± 4.86 %). Wilcoxon tests showed a significant effect of compatibility on RTs (sham: Z = 2.7, p = 0.007; rTMS: Z = 2.8, p = 0.005) and accuracy rate (sham: Z = 2.5, p = 0.01; rTMS: Z = 2.1, p = 0.03), subjects being slower and making more errors in compatible trials (sham: 391.64 ± 52 ms, 87.3 % of accuracy; rTMS: 396.66 ± 37 ms, 86.3 % of accuracy) in comparison to incompatible trials (sham: 357.45 ± 36 ms, 92.5 % of accuracy; rTMS: 356.25 ± 28 ms, 92.7 % of accuracy), suggesting motor inhibition. However, this NCE was preserved after rTMS over the SMA (RTs: Z = 0.87, p = 0.39; accuracy rate: Z = 0.71, p = 0.47). Conclusions: We conclude that long trains of low intensity 1 Hz rTMS did not affect the modulation of RT by subliminal stimuli, suggesting that the SMA might not be mandatory for the implementation of this automatic process. The limitation of this study is relative to the neural efficacy argument because we are not sure that TMS was strong enough to disturb the redundant organizational processing in the SMA or that other regions were not able to compensate for the virtually lesioned area.
Disciplines :
Neurosciences & behavior
Neurology
Author, co-author :
D'Ostilio, Kevin ;  Université de Liège - ULiège > Centre de recherches du cyclotron
CREMERS, Julien ;  Centre Hospitalier Universitaire de Liège - CHU > Neurologie Sart Tilman
DELVAUX, Valérie ;  Centre Hospitalier Universitaire de Liège - CHU > Neurologie Sart Tilman
GARRAUX, Gaëtan  ;  Centre Hospitalier Universitaire de Liège - CHU > Neurologie Sart Tilman
Language :
English
Title :
Preserved automatic inhibition effect after 1 Hz repetitive transcranial magnetic stimulation over the supplementary motor area
Publication date :
2013
Event name :
5 th International Conference on non-Invasive Brain stimulation
Event place :
Germany
Event date :
du 19 mars au 21 mars 2013
Audience :
International
Available on ORBi :
since 05 March 2013

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