Curry software

Current densities for the representing time points of TMS-induced components were estimated by using the standardized low resolution brain electromagnetic tomography [(sLORETA), Pascual-Marqui et al., 2002 (link)] in the Curry software (version 6.0.20, Compumedics Neuroscan, Victoria, Australia) for the illustrative purposes. Current density estimations were analyzed for each group separately and the visualized time points were defined as local maximum values of GMFP. The EEG data and the digitized locations of EEG electrodes were combined with a realistic head model [a three-compartment boundary element model and standard conductivity values (0.33 S/m for the brain fluid, 0.0042 S/m for skull, and 0.33 S/m for skin)] for current source analysis (Ferreri et al., 2016 (link)).

Each subject had post-operative anterior–posterior and lateral radiographs (Figure 4), as well as computer tomography (CT) scans to verify ECoG grid locations. Three-dimensional cortical models of individual subjects were generated using pre-operative structural magnetic resonance (MR) imaging. These MR images were co-registered with the post-operative CT images using Curry software (Compumedics, Charlotte, NC) to identify electrode locations. Electrode locations were assigned to Brodmann areas using the Talairach Daemon (http://www.talairach.org, (Lancaster et al., 2000 (link)). Activation maps computed across subjects were projected on this 3D brain model, and were generated using a custom Matlab program (Gunduz et al., 2012 (link)).

The locations of the contacts relative to brain anatomy were determined by co-registering the preoperative MRI of the brain with the head CT scan for SEEG electrode locations and CT scan for RNS electrode locations. We have recently developed a semi-automated identification process of anatomical labelling for intracranial electrode contacts, details of which are described in Tayler et al.^{52 (link)} In brief, the preoperative MRI of each patient was imported to BrainSuite^{53 (link)} and an anatomical segmentation was performed based on the USCBrain atlas.^{54 (link)} The SEEG contacts locations are determined from the CT using the Curry software (Compumedics, NeuroScan Laboratories, Charlotte, NC, USA), and the outputs are combined to localize and automatically assign anatomical labels to each contact. The contact locations of RNS were identified in the same manner. The distances between each SEEG and each RNS contact were calculated using an in-house MATLAB script (the Mathworks, Inc., Natick, MA, USA). BrainSuite^{53 (link)} and BrainStorm software^{55 (link)} were used to confirm the locations of the contacts of SEEG and RNS electrodes within the brain volumes.

Continuous EEG data were recorded using Curry software (Version 7; Compumedics Ltd., USA) from 64 Ag/AgCl scalp electrodes mounted on an electrode cap (Easycap, Brainworks, GmbH) according to the International 10–10 system [41 ] (Fpz, Fz, FCz, Cz, CPz, Pz, Oz, Fp1/2, AF7/3/1/2/4/8, F7/5/3/1/2/4/6/8, FT7/8, FC5/3/1/2/4/6, T7/8, C5/3/1/2/4/6, M1/2, TP7/8, CP5/3/1/2/4/6, P7/5/3/1/2/4/6/8, PO7/5/3/4/6/8, O1/2). Ground was located at AFz. Electrooculographic activity was measured from electrodes placed above and below the right orbit and at the outer canthus of each eye. Electrode impedances were kept below 10kΩ. Electrical activity was recorded from both mastoids, with the left mastoid as the on-line reference. The EEG signal was digitised at a sampling rate of 1000 Hz and filtered with a .05–100 Hz bandpass filter using a Neuroscan SynAmps2 DC Amplifier (Compumedics Ltd., USA).
The EEG recording lasted between one and one and a half hours for each participant, including breaks. After the EEG recording, participants completed a post-task questionnaire in which they were asked to rate the strength of the foreign-accented speaker’s accent on a seven-point scale from ‘No foreign accent’ (1) to ‘Very strong foreign accent’ (7), and to identify the nationality of the foreign-accented speaker. In all, the testing session for each participant lasted approximately two and a half hours.