Preparatory slow potentials and event-related potentials in an auditory cued attention task

To examine reaction times and event-related potentials (ERPs) in an auditory cued attention task varying motor requirements, cue validity, and cue location.

Subjects (n=13) listened to cue-target stimulus pairs. Verbal cues (monaural, binaural) indicated the ear to receive a target tone 1.5s later. Cues correctly (valid) or incorrectly (invalid) predicted target ear, or were uninformative (neutral). In separate conditions subjects either responded by pressing one of two buttons, or did not respond to targets. ERPs for cues and targets (P50, N100, P200, late slow wave), and negative slow potentials between cues and targets were assessed.

Target reaction times for valid cues were significantly shorter than for invalid cues, with intermediate values for neutral cues. When no motor response was required larger ERPs were seen to both cues and targets. Negative slow potentials had larger amplitudes before target presentation when subjects responded to targets; and were larger following neutral, vs. valid/invalid, cues. ERPs (N100, P200) to invalidly cued targets were significantly larger and a subsequent late slow wave was more positive, relative to validly cued targets.

Expectancy for targets begins shortly after cue presentation, and is affected by both motor requirements and the information content of the cue. ERP amplitudes to targets are modulated by the correspondence between cue information and actual target location.