Limits...
From oscillatory transcranial current stimulation to scalp EEG changes: a biophysical and physiological modeling study.

Merlet I, Birot G, Salvador R, Molaee-Ardekani B, Mekonnen A, Soria-Frish A, Ruffini G, Miranda PC, Wendling F - PLoS ONE (2013)

Bottom Line: In order to account for tCS effects and following current biophysical models, the calculated component of the electric field normal to the cortex was used to locally influence the activity of neuronal populations.Moreover, additional information was also brought by the model at other electrode positions or stimulation frequency.This suggests that our modeling approach can be used to compare, interpret and predict changes occurring on EEG with respect to parameters used in specific stimulation configurations.

View Article: PubMed Central - PubMed

Affiliation: INSERM, Université de Rennes 1, LTSI, Rennes, France. isabelle.merlet@univ-rennes1.fr

ABSTRACT
Both biophysical and neurophysiological aspects need to be considered to assess the impact of electric fields induced by transcranial current stimulation (tCS) on the cerebral cortex and the subsequent effects occurring on scalp EEG. The objective of this work was to elaborate a global model allowing for the simulation of scalp EEG signals under tCS. In our integrated modeling approach, realistic meshes of the head tissues and of the stimulation electrodes were first built to map the generated electric field distribution on the cortical surface. Secondly, source activities at various cortical macro-regions were generated by means of a computational model of neuronal populations. The model parameters were adjusted so that populations generated an oscillating activity around 10 Hz resembling typical EEG alpha activity. In order to account for tCS effects and following current biophysical models, the calculated component of the electric field normal to the cortex was used to locally influence the activity of neuronal populations. Lastly, EEG under both spontaneous and tACS-stimulated (transcranial sinunoidal tCS from 4 to 16 Hz) brain activity was simulated at the level of scalp electrodes by solving the forward problem in the aforementioned realistic head model. Under the 10 Hz-tACS condition, a significant increase in alpha power occurred in simulated scalp EEG signals as compared to the no-stimulation condition. This increase involved most channels bilaterally, was more pronounced on posterior electrodes and was only significant for tACS frequencies from 8 to 12 Hz. The immediate effects of tACS in the model agreed with the post-tACS results previously reported in real subjects. Moreover, additional information was also brought by the model at other electrode positions or stimulation frequency. This suggests that our modeling approach can be used to compare, interpret and predict changes occurring on EEG with respect to parameters used in specific stimulation configurations.

Show MeSH

Related in: MedlinePlus

Example of simulated EEGs during variable frequency of tACS stimulation.A clear increase of the amplitude of alpha spindles is visible for 10 Hz- and 12 Hz- tACS but not for 6 Hz- or 14 Hz-tACS.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585369&req=5

pone-0057330-g007: Example of simulated EEGs during variable frequency of tACS stimulation.A clear increase of the amplitude of alpha spindles is visible for 10 Hz- and 12 Hz- tACS but not for 6 Hz- or 14 Hz-tACS.

Mentions: As compared to 10 Hz-tACS, 11 Hz and 12 Hz-tACS on the one hand, and 9 Hz and 8 Hz-tACS on the other hand had a progressively decreasing effect on alpha power density. An illustration is given for chosen frequencies on Figure 7. No significant effect was observed on simulated EEG when applying tACS at frequency outside of the [8 Hz–12 Hz] range (Figure 8).


From oscillatory transcranial current stimulation to scalp EEG changes: a biophysical and physiological modeling study.

Merlet I, Birot G, Salvador R, Molaee-Ardekani B, Mekonnen A, Soria-Frish A, Ruffini G, Miranda PC, Wendling F - PLoS ONE (2013)

Example of simulated EEGs during variable frequency of tACS stimulation.A clear increase of the amplitude of alpha spindles is visible for 10 Hz- and 12 Hz- tACS but not for 6 Hz- or 14 Hz-tACS.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585369&req=5

pone-0057330-g007: Example of simulated EEGs during variable frequency of tACS stimulation.A clear increase of the amplitude of alpha spindles is visible for 10 Hz- and 12 Hz- tACS but not for 6 Hz- or 14 Hz-tACS.
Mentions: As compared to 10 Hz-tACS, 11 Hz and 12 Hz-tACS on the one hand, and 9 Hz and 8 Hz-tACS on the other hand had a progressively decreasing effect on alpha power density. An illustration is given for chosen frequencies on Figure 7. No significant effect was observed on simulated EEG when applying tACS at frequency outside of the [8 Hz–12 Hz] range (Figure 8).

Bottom Line: In order to account for tCS effects and following current biophysical models, the calculated component of the electric field normal to the cortex was used to locally influence the activity of neuronal populations.Moreover, additional information was also brought by the model at other electrode positions or stimulation frequency.This suggests that our modeling approach can be used to compare, interpret and predict changes occurring on EEG with respect to parameters used in specific stimulation configurations.

View Article: PubMed Central - PubMed

Affiliation: INSERM, Université de Rennes 1, LTSI, Rennes, France. isabelle.merlet@univ-rennes1.fr

ABSTRACT
Both biophysical and neurophysiological aspects need to be considered to assess the impact of electric fields induced by transcranial current stimulation (tCS) on the cerebral cortex and the subsequent effects occurring on scalp EEG. The objective of this work was to elaborate a global model allowing for the simulation of scalp EEG signals under tCS. In our integrated modeling approach, realistic meshes of the head tissues and of the stimulation electrodes were first built to map the generated electric field distribution on the cortical surface. Secondly, source activities at various cortical macro-regions were generated by means of a computational model of neuronal populations. The model parameters were adjusted so that populations generated an oscillating activity around 10 Hz resembling typical EEG alpha activity. In order to account for tCS effects and following current biophysical models, the calculated component of the electric field normal to the cortex was used to locally influence the activity of neuronal populations. Lastly, EEG under both spontaneous and tACS-stimulated (transcranial sinunoidal tCS from 4 to 16 Hz) brain activity was simulated at the level of scalp electrodes by solving the forward problem in the aforementioned realistic head model. Under the 10 Hz-tACS condition, a significant increase in alpha power occurred in simulated scalp EEG signals as compared to the no-stimulation condition. This increase involved most channels bilaterally, was more pronounced on posterior electrodes and was only significant for tACS frequencies from 8 to 12 Hz. The immediate effects of tACS in the model agreed with the post-tACS results previously reported in real subjects. Moreover, additional information was also brought by the model at other electrode positions or stimulation frequency. This suggests that our modeling approach can be used to compare, interpret and predict changes occurring on EEG with respect to parameters used in specific stimulation configurations.

Show MeSH
Related in: MedlinePlus