The N2 Wave of Event-Related Potentials Reflects the Novelty of the Eliciting Stimuli

Abstract

[LANGUAGE= "English"] Purpose: The typical novelty paradigm in cognitive electrophysiology is an experimental design, in which the effects of novel stimuli on brain electrical activity are measured using unexpected and ever-changing novel non- target stimuli interspersed in the set of standards and targets of the classical oddball paradigm. The typical event-related potential (ERP) component obtained during the novelty paradigm is a N2-P3a complex occurring in response to novel non-targets. The aim of present study is to determine more specific ERP component for detection of novelty.

Material and Methods: We recorded visual ERP from 9 electrode sites (international 10/20 system) on ten healthy volunteer subjects participated in our study. We applied a new experimental paradigm, in which novel stimuli were placed as task-relevant targets instead of being distracting non-targets, and we compared the ERPs elicited with the novel targets in this paradigm both with those elicited by novel non-targets in the novelty paradigm and by constant targets in the standard oddball paradigm.

Results: Obtained data show that the P3 potentials were affected both by the novelty and the targetness of the eliciting stimuli. However, the N2 potential generated by the novel targets did not show any significant difference to the novel non-targets, and was significantly higher in amplitude compared with those of the ERPs to typical targets.

Conclusion: The greater N2 wave observed both in responses to novel targets and novel non-targets is the real index of the novelty of inducing stimuli.

Alternate abstract:

Purpose: The typical novelty paradigm in cognitive electrophysiology is an experimental design, in which the effects of novel stimuli on brain electrical activity are measured using unexpected and ever-changing novel non- target stimuli interspersed in the set of standards and targets of the classical oddball paradigm. The typical event-related potential (ERP) component obtained during the novelty paradigm is a N2-P3a complex occurring in response to novel non-targets. The aim of present study is to determine more specific ERP component for detection of novelty.

Material and Methods: We recorded visual ERP from 9 electrode sites (international 10/20 system) on ten healthy volunteer subjects participated in our study. We applied a new experimental paradigm, in which novel stimuli were placed as task-relevant targets instead of being distracting non-targets, and we compared the ERPs elicited with the novel targets in this paradigm both with those elicited by novel non-targets in the novelty paradigm and by constant targets in the standard oddball paradigm.

Results: Obtained data show that the P3 potentials were affected both by the novelty and the targetness of the eliciting stimuli. However, the N2 potential generated by the novel targets did not show any significant difference to the novel non-targets, and was significantly higher in amplitude compared with those of the ERPs to typical targets.

Conclusion: The greater N2 wave observed both in responses to novel targets and novel non-targets is the real index of the novelty of inducing stimuli.