The pattern flash elicited P300-complex (PF-P300): dynamics of its topographic scalp distribution in different states of visual attention.

PF-P300 has been recorded from 13 healthy male subjects (21-35 years) in two different conditions of visual attention (transient versus sustained attention) at 16 electrode locations (10/20-system) against linked mastoids. The PFP300 complexes were measured and mapped. Thus, we obtained the following: (1) N250 did not show any significant differences between both conditions. (2) PF-P300, however, showed significantly different (p less than or equal to .05) maps between both conditions, especially bilateral frontal and left occipital with the measured PFP300a-amplitudes being higher (p less than or equal to .01) under sustained attention. The PFP300a-latencies did not show such differences. (3) N400 showed similar (p less than or equal to .001) differences in its mean peak distribution, but its latencies were shorter (p less than or equal to .01 resp. .0001) at all recording sites (except Fz, Pz) in condition (2). (4) Further evaluation of the PFP300-complex under sustained attention by means of increment mapping and multichannel potential measurements showed that PFP300 first rises at Fz, Pz, then spreads over the left occipital region and culminates bilateral frontal and parieto-occipital. Interestingly, the latencies of N250 and PFP300a were shorter at O1 (p less than or equal to .01) than at O2. With the help of electrical brain mapping it is possible to study the dynamics of both the PFP300 scalp distribution between two distinct mental states and within one mental state.