Magpro x100 system

TMS was delivered with a figure-of-eight coil (MC-B70 with outer diameter of each wing 97 mm) connected to a biphasic MagPro X100 system (MagVenture, Skovlunde, DK) over the left motor cortex to elicit motor evoked potentials (MEPs) at the right FDI muscle.^{25 (link)} Resting motor threshold (RMT) and active motor threshold (AMT) were determined according to standard procedures.^{26 (link)}Facilitatory circuits were evaluated by the intracortical facilitation (ICF) and the short-interval intracortical facilitation (SICF) protocols, while inhibitory circuits by SICI, long-interval intracortical inhibition (LICI) and CSP.^{27 (link)}SICI–ICF, SICF and LICI were studied with a paired-pulse model with a conditioning-test design. For all paradigms, the test stimulus (TS) was adjusted to evoke an MEP of 1 mV amplitude. The interstimulus interval (ISI) between TS and conditioning stimulation differed among protocols (see Supplementary Data and Table 1). Fifteen trials were recorded for each ISI and each protocol randomly intermixed with 15 trials of TS alone (0.2 Hz ± 10%). The ratio of the mean amplitude of the conditioned response to that of the TS response (unconditioned response) was calculated for each condition and ISI in each subject.

Participants were screened for contraindications related to fMRI and to single-pulse TMS and cTBS according to common safety guidelines (Rossi et al., 2009 (link); Oberman et al., 2011 (link)). Resting motor thresholds (RMTs) and active motor thresholds (AMTs) were established for the first dorsal interosseous muscle of the subject’s right hand using electromyography. TMS was applied using a hand-held biphasic figure-eight coil with a 75 mm outer winding diameter (MagVenture), connected to a MagProX100 System (MagVenture). Coil orientation was chosen to induce a posterior–anterior electrical field in the brain (45° from the mid-sagittal axis).
Subjects performed five runs of an interleaved pro-saccade (look toward)/anti-saccade (look away) task to identify the cortical regions of interest (ROIs; Fig. 2B). An interleaved task was used as evidence suggests an important role for DLPFC (Everling and DeSouza, 2005 (link); Johnston et al., 2014 (link)) as well as for FEF (DeSouza and Everling, 2010 (link)) in task or preparatory set and thus could not simply default to an anti-saccade task set on each trial. Two target positions (13° or 9°) in the left and right directions were included so that subjects would have to rely on spatial information to calculate the saccade vector. In this way, we could be sure that the paradigm required DLPFC, FEF, and PPC processes.