Event-related brain potentials to attended and ignored olfactory and trigeminal stimuli

Event-related brain potentials (ERPs) were recorded from 26 young adults, w ith equal numbers of male and female subjects, using attended and ignored, olfactory and trigeminal stimuli. The amplitudes and latencies of the N1, P 2, and P3 components were recorded using a single-stimulus paradigm, with a n inter-stimulus interval of 60 s, employing amyl acetate as the olfactory stimulus and ammonia as the trigeminal stimulus. Subjects estimated stimulu s intensity in the attend condition or continued with a visual tracking tas k in the ignore condition. Results indicate that olfactory information is p rocessed 30-70 ms faster than trigeminal information for the N1 and P2 pote ntial and 100 ms faster for the P3 ERP component. N1/P2 interpeak amplitude was greater for the trigeminal than the olfactory stimuli, and greater in the attended than ignored condition. P3 amplitude was greater in the attend than ignore condition for olfactory information processing and equivalent for trigeminal information processing. These findings suggest that neuronal resource allocation is greatest for attended stimuli and that a painful st imulus demands neuronal resources even when ignored. (C) 2000 Elsevier Scie nce B.V. All rights reserved.