[Effect of forward masking on evoked potentials of auditory cortex in guinea pigs]

Thresholds of the event-related potentials (ERPs) appearance were measured for one stationary and four moving auditory images presented in silence or under forward masking conditions. The difference between thresholds in silence and after noise masker was considered as masking level. Under the forward masking, the amplitude of the ERP to the first click in the test series decreased in guinea pig auditory cortex. Masking level decreased with the time lag between signal and masker and didn't depend on the fused auditory image localization that corresponded to the first click in different test signals. This fact can support the hypothesis that for the long test signals the initial part can be masked more than the final one. The ERPs amplitude to next clicks in test series depended on interaction of two factors: forward masking in the "masker-signal" system and interaction of separate ERPs in the series evoked by the test signal.