The visual and auditory cues were the same as those used before, but this time they were presented 2.5 sec before the string “xxxxxx” or the sound corresponding to the letter “x”, respectively. The time in between successive cue onsets varied randomly between 5 and 5.5 sec as in the memorization task. The second task also had an easy and difficult version, each incorporating 48 stimuli in separate blocks. The accuracy and speed with which

visual and auditory cues could be discriminated in these simple tasks were contrasted with discrimination performance during word list memorization. EEG was recorded from 32 scalp sites with sintered silver/silver-chloride electrodes embedded GSK1120212 in vitro in an elastic cap. Electrodes were positioned according to an equidistant montage (www.easycap.de/easycap/e/electrodes/13_M10.htm).

Vertical and horizontal eye movements were recorded bipolarly from electrodes placed above and below the right eye and on the outer canthus of each eye. A midfrontal site (corresponding to Fz in the 10/20 system) was used as the online reference. Impedances were kept below 5 kΩ. Online, signals were amplified, band-pass filtered between .01 and 35 Hz (3 dB roll-off), and digitized at a rate of 500 Hz (12-bit resolution). Offline, the data were digitally filtered between .05 and 20 Hz with a 96 dB roll-off, zero phase shift filter and algebraically re-referenced to linked mastoids. The online midfrontal site was re-instated selleck and used as

a scalp site of interest. Signals were downsampled to 100 Hz to assess cue-related activity and to 125 Hz to assess word-related activity. The primary interest was in encoding-related activity elicited by cues. However, for completeness, we also computed encoding-related activity elicited by words. Activity elicited by cues and words was analyzed separately to allow each to be aligned to the time period immediately Thalidomide before each event (Galli et al., 2011; Gruber and Otten, 2010; Otten et al., 2006, 2010). This approach assesses whether words elicit encoding-related activity above and beyond any encoding-related activity elicited by cues. EEG epochs of 2560 and 2048 msec duration were extracted from the continuous record surrounding cues and words, respectively, each starting 100 msec before their onset. The slight differences in epoch length reflected the periods of time in which encoding-related effects were expected. Event-related potentials (ERPs) were generated for each participant and electrode site, separately for cues in each modality and discrimination difficulty condition. Blink artifacts were minimized with a linear regression procedure (Rugg et al., 1997) and trials containing non-blink eye movements, drifts (±50 μV), amplifier saturation, or muscle artifacts were excluded from the averaging process.