Personalizing the Electrode to Neuromodulate an Extended Cortical Region

A Cancelli; C Cottone; M Di Giorgio; F Carducci; F Tecchio

doi:10.1016/j.brs.2015.01.398

Personalizing the Electrode to Neuromodulate an Extended Cortical Region

Brain Stimul. 2015 May-Jun;8(3):555-60. doi: 10.1016/j.brs.2015.01.398. Epub 2015 Jan 14.

Authors

A Cancelli¹, C Cottone², M Di Giorgio³, F Carducci⁴, F Tecchio⁵

Affiliations

¹ Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy; Institute of Neurology, Department of Geriatrics, Neurosciences & Orthopaedics, Catholic University of Sacred Heart, Rome, Italy.
² Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy; Department of Neuroscience and Imaging, G. d'Annunzio University of Chieti - Pescara, Italy.
³ AFaR Division, Fatebenefratelli Foundation for Health Research and Education, Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy.
⁴ Department of Physiology and Pharmacology, Neuroimaging Laboratory, University of Rome "Sapienza", Italy.
⁵ Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy; Department of Neuroimaging, IRCCS San Raffaele Pisana, Rome, Italy. Electronic address: franca.tecchio@cnr.it.

PMID: 25680321
DOI: 10.1016/j.brs.2015.01.398

Abstract

Background: Among transcranial electric stimulation (tES) parameters, personalizing the electrode geometry might help overcome the individual variability of the induced effects.

Objective/hypothesis: To test the need for electrode personalization, instead of a universal electrode for everyone, to induce neuromodulation effects on the bilateral primary motor cortex (M1) devoted to upper and lower limb representation.

Methods: By an ad-hoc neuronavigation procedure, we shaped the personalized electrode and positioned it matching the projection on the scalp of the individual central sulcus by a 2 cm strip, with total area of 35 cm(2). The non-personalized electrode, i.e., equal for all subjects, was a 2 cm wide strip size-matched with the personalized electrode but shaped on a standard model fitting the curve passing through C3-CZ-C4 sites of the electroencephalographic (EEG) 10-20 International System. To test neuromodulation electrode-dependent efficacy, we induced a 20 Hz sinusoidal modulated current (transcranial alternating current stimulation, tACS) because it produces online effects. We simultaneously collected left and right hand and leg motor potentials (MEP) that were evoked by a rounded transcranial magnetic stimulation (TMS) coil. Through each electrode we delivered both real and sham stimulations.

Results: While cortical excitability during tACS increased during both the non-personalized and the personalized electrodes for the leg, the hand representation excitability enhancement was induced selectively when using the personalized electrode. The results were consistent bilaterally.

Conclusions: We documented that by using a personalized electrode it is possible to induce the neuromodulation of a predetermined extended cortical target, which did not occur with a non-personalized electrode. Our findings can help in building neuromodulation methods that might compensate for individual alterations across specific brain networks.

Keywords: Cortical target; Electrode personalization; Neuronavigation; Transcranial alternating current stimulation (tACS).

MeSH terms

Adult
Cerebral Cortex / physiology*
Electrodes*
Electroencephalography
Female
Humans
Male
Middle Aged
Neuronavigation
Scalp / physiology
Transcranial Direct Current Stimulation / instrumentation*
Transcranial Magnetic Stimulation / methods