F.G. and L.T. contributed equally to this article.
The spontaneous fluctuation of the excitability of a single node modulates the internodes connectivity: A TMS-EEG study
Article first published online: 14 MAY 2013
Copyright © 2013 Wiley Periodicals, Inc.
Human Brain Mapping
Volume 35, Issue 4, pages 1740–1749, April 2014
How to Cite
Giambattistelli, F., Tomasevic, L., Pellegrino, G., Porcaro, C., Melgari, J. M., Rossini, P. M. and Tecchio, F. (2014), The spontaneous fluctuation of the excitability of a single node modulates the internodes connectivity: A TMS-EEG study. Hum. Brain Mapp., 35: 1740–1749. doi: 10.1002/hbm.22288
- Issue published online: 20 MAR 2014
- Article first published online: 14 MAY 2013
- Manuscript Accepted: 18 FEB 2013
- Manuscript Revised: 15 FEB 2013
- Manuscript Received: 4 MAY 2012
- European Community's Seventh Framework Programme (project MEGMRI). Grant Number: 200859
- Italian Ministry of Health (“Promoting recovery from Stroke: Individually enriched therapeutic intervention in Acute phase” [ProSIA]). Grant Number: Cod. GR-2008-1138642
- Italian Foundation for Multiple Sclerosis (FISM). Grant Number: Cod. 2010/R/38
- transcranial magnetic stimulation simultaneous to electroencephalographic recordings;
- cerebral connectivity as localized cortical recruitment;
- spontaneous fluctuation of excitability
Brain effective connectivity can be tracked by cerebral recruitments evoked by transcranial magnetic stimulation (TMS), as measured by simultaneous electroencephalography (TMS-EEG). When TMS is targeting the primary motor area, motor evoked potentials (MEPs) can be collected from the “target” muscles. The aim of this study was to measure whether or not effective brain connectivity changes with the excitability level of the corticospinal motor pathway (CSMP) as parameterized by MEP amplitude. After averaging two subgroups of EEG-evoked responses corresponding to high and low MEP amplitudes, we calculated the individual differences between them and submitted the grand average to sLORETA algorithm obtaining localized regions of interest (RoIs). Statistical differences of RoI recruitment strength between low and high CSMP excitation was assessed in single subjects. Preceding the feedback arrival, neural recruitment for stronger CSMP activation were weaker at 6–10 ms of homotopic sensorimotor areas BA3/4/5 of the right nonstimulated hemisphere (trend), weaker at 18–25 ms of left parietal BA2/3/40, and stronger at 26–32 ms of bilateral frontal motor areas BA6/8. The proposed method enables the tracking of brain network connectivity during stimulation of one node by measuring the strength of the connected recruited node activations. Spontaneous increases of the excitation of the node originating the transmission within the hand control network gave rise to dynamic recruitment patterns with opposite behaviors, weaker in homotopic and parietal circuits, stronger in frontal ones. The effective connectivity within bilateral circuits orchestrating hand control appeared dynamically modulated in time even in resting state as probed by TMS. Hum Brain Mapp 35:1740–1749, 2014. © 2013 Wiley Periodicals, Inc.