مرکز منطقه ای اطلاع رساني علوم و فناوري - Novelty N2 response reflects time-dependent classification of target stimuli in humans

Abstract :

Novel, unexpected or unpredictable stimuli induce the involuntary capture of attention and evoke an orienting response. The novelty paradigm is a modification of classical oddball task in which unexpected and ever-changing novel non-target stimuli are inserted into the sequence of infrequent target and frequent standard stimuli. The typical eventrelated potential (ERP) component is an N2b-P3a complex occurring in response to novel non-targets during the novelty paradigm. The aim of this study is to investigate the effects of target-novel interval changes on the auditory N2b-P3a complex. Twenty-one healthy volunteers (ages between 19 and 24 years) participated in the study. ERPs were recorded with 30 electrodes using an auditory novelty paradigm. Between target and novel stimuli intervals were randomly changed at 4, 6, 10, and 14 s. Obtained EEG trials from the responses to novel stimuli were separately averaged in each interval group. The amplitude and latency of N2b and P3a potentials in average responses were measured and then analyzed by repeated measures analyses of variance (ANOVA). Statistical analyses indicate that the amplitudes of N2b were significantly bigger in the ERP trials with shorter target-novel intervals at all electrode sites (p 0.05). However, the amplitudes and latencies of P3a responses were not different among the interval groups (p 0.05). Our results suggest that the target-novel intervals modulate novelty N2 wave amplitudes. Therefore, the analysis of novelty N2 responses in conjunction with target-novel intervals can introduce further specificity to the ERP findings.