The P3(00) event-related potential (ERP) component is usually reported as h
aving a centro-parietal maximum. However, the P3 topography is more frontal
in early-session trials which may be masked by averaging over the entire s
ession and is evident longer into the test session among elderly subjects.
This hyperfrontality is interpreted as a sign of poor prefrontal adaptive f
unctioning. Tn the present study, P3 amplitude was examined in university s
tudents to deter mine how early a change in amplitude would be evident and
the effect of task complexity on the amplitude across electrode sites. ERPs
were elicited using a working-memory n-back task where participants presse
d a key to target letter presentations in three conditions of increasing co
mplexity. Single-trial ERP waveforms were then averaged in successive seque
nces of five trials. Results revealed a greater decrease in frontal P3 ampl
itude compared to the central and parietal P3 after the first block of five
target trials until the third block. The results are interpreted as indica
ting rapid decrease in hyperfrontality with habituation to an easy task. In
creases in task complexity (the 2-back paradigm), however, reduced this fro
ntal P3 attenuation. Results support a P3 ERP model of hyperfrontality refl
ecting short-term adaptive function by the pre-frontal cortex. (C) 2001 Aca
demic Press.