Finally, rapid automatized naming was assessed using the object and digit sheets from the PhAB (Frederickson et al., 1997) and two custom-made color

sheets. The dependent FK228 supplier variable is the total time taken to name all items on each sheet, irrespective of errors. Auditory steady state responses (ASSR) were induced using an amplitude-modulated white noise presented binaurally at 65 dB SPL. The sound modulation rate linearly increased from 10 to 80 Hz in 5.4 s (Poulsen et al., 2007) (Figures 1A and 1B). The sound was surrounded by 0.3 s of unmodulated white noise to prevent onset and offset effects. This 6 s (5.4 + 2 × 0.3 s) stimulus was presented 80 times (silent interstimuli interval (ISI): 2–4 s) during two sessions of 40 trials each. Participants watched a mute wildlife documentary during the experiment to ensure sustained vigilance (Wilson et al., 2007) and were asked to blink during ISI to prevent artifacts during the stimuli. Data were preprocessed and analyzed using in-house software (http://cogimage.dsi.cnrs.fr/logiciels/). ASSR were recorded using a CTF Systems MEG device, with 151 radial gradiometers over the scalp and 29 reference gradiometers and magnetometers

for ambient field correction (1,250 Hz sampling rate; 300 Hz online low pass filter). Trials contaminated with eye movements, blinks, and cardiac or muscular activity were rejected offline Selleck Tariquidar (Gratton et al., 1983). Remaining MEG trials were averaged from 0.3 s pre- to 6.3 s poststimulus onset and high-pass filtered at 0.26 Hz. PD184352 (CI-1040) After a baseline adjustment on the 300 ms prestimulus period, the averaged signal was used to compute cortical current maps with BrainStorm (http://neuroimage.usc.edu/brainstorm) using the weighted minimum-norm estimation approach. We estimated 15,000 cortically distributed current dipoles, whose locations (but not orientations) were constrained onto the gray

matter surface of either the individual brain images when available or the BrainStorm generic brain model built from the standard brain of the Montreal Neurological Institute (MNI colin27). Individual structural MRI could be acquired (Tim-Trio, Siemens; 7 min anatomical T1-weighted magnetization-prepared rapid acquisition gradient echo sequence, 176 slices, field of view = 256, voxel size = 1 × 1 × 1 mm) in 29 participants (14 controls/15 dyslexics: subjects 1–9, 11, 12, 14–18, 20–22, 25–35, and 38; see green frame in Figure S1). Head and cortex meshes were extracted with BrainVISA version 4.0 (http://brainvisa.info/). When individual MRI images could be used, source estimates were in a second step projected onto the standard MNI colin27: after realignment and deformation of the subject cortex surface to the Colin cortex surface, the sources amplitudes are interpolated from the subject surface to the Colin surface using Shepard’s method (weighted combination of a few nearest neighbors).