SCN stimuli were generated using Praat code (based on code from Matt Davis, MRC Cognition and Brain Sciences Unit, Cambridge). Reversed speech The reversed speech baseline was created by reversing the speech stimulus in time, as if it was played backwards from end to start. Procedure In order to track the time-evolving response that reflects phrasal-level processing, we employed a continuous sampling paradigm (simultaneous scanning and stimulus presentation). While background noise may partially mask the auditory stimuli and reduce sensitivity
somewhat, continuous Inhibitors,research,lifescience,medical sampling is still advantageous in that it enhances statis-tical power and shortens scan time significantly, simply by collecting more images per scan minute, and speeding up the stimulus presentation rate. Stimuli of three conditions, Speech, Reversed, and SCN, were presented in a simple block design, for the purpose of improving
sensitivity in individual subjects. Blocks consisted of a single paragraph, Inhibitors,research,lifescience,medical 15 sec long, and were interleaved with 12.5 sec rest epochs (see Fig. 1). In order to ensure that subjects were paying attention during stimulus presentation, they performed an auditory detection task of auditory “blip” cues and responded with a button press (three cues randomly placed in each experimental block, scaled to the same intensity as the auditory stimuli). This orthogonal Inhibitors,research,lifescience,medical task allowed us to direct and BLZ945 monitor Inhibitors,research,lifescience,medical participant’s attention to auditory stimuli of all conditions. Figure 1 Experimental design. Schematic plot of a single experimental run. The experiment consisted of two runs, each containing a total of six blocks (interleaved with rest blocks), two blocks for each stimulus type. Block presentation was pseudorandomized, so … Before entering the scanner, subjects underwent Inhibitors,research,lifescience,medical a brief training session in order to get familiarized with the task and the different stimulus types. Participants were instructed to maintain their gaze on a central fixation cross which appeared throughout the entire experiment, listen attentively to all auditory secondly stimuli, and respond when
they hear the target cue. E-Prime 2.0 (Psychology Software Tools, Pittsburgh, PA) was used for stimulus presentation and response collection. Stimuli were delivered to the subjects via MR compatible headphones, which are part of a customized recording system (FOMRI-III; Optoacoustics, Israel) implementing active noise cancelation. A short auditory test was delivered during scanning to confirm that subjects could hear the stimuli clearly above the scanner noise. The experiment was divided into two short runs (3:20 min long each), separated by a short break. A single run consisted of six experimental blocks (interleaved with rest blocks), with two blocks of each of the three conditions randomized so that no two consecutive blocks were of the same type (Fig. 1).