LONG-TERM STIMULATION ATTENUATES THE TRANSIENT 40-HZ RESPONSE

THE effect of long-term stimulation on the transient 40-Hz response wa s studied in 5-h long experimental sessions. Ten human subjects were p resented with series of 1000 Hz tone pips occasionally replaced by 120 0 Hz tone pips. The transient 40-Hz response was compared with two eve nt-related potential (ERP) components, the N1 and the mismatch negativ ity (MMN) during the different phases of the long-lasting sessions. Th e 40-Hz and N1 onset responses attenuated while the MMN did not. Thus, the 40-Hz response might indicate vigilance.