[WMN: a negative ERPs component related to working memory during non-target visual stimuli processing].
OBJECTIVE
To study non-target stimuli processing in the brain.


METHODS
Features of the event-related potentials (ERPs) from non-target stimuli during selective response task (SR) was compared with that during visual selective discrimination (DR) task in 26 normal subjects. The stimuli consisted of two color LED flashes (red and green) appeared randomly in left (LVF) or right (RVF) visual field with same probability. ERPs were derived at 9 electrode sites on the scalp under 2 task conditions: a) SR, making switch response to the target (NT) stimuli from LVF or RVF in one direction and making no response to the non-target (NT) ones; b) DR, making switching response to T stimuli differentially, i.e., to the left for T from LVF and to the right for T from RVF.


RESULTS
1) the non-target stimuli in DR conditions, compared with that in SR condition, elicited smaller P2 and P3 components and larger N2 component at the frontal brain areas; 2) a significant negative component, named as WMN (working memory negativity), appeared in the non-target ERPs during DR in the period of 100 to 700 ms post stimulation which was predominant at the frontal brain areas.


CONCLUSIONS
According to the major difference between brain activities for non-target stimuli during SR and DR, the predominant appearance of WMN at the frontal brain areas demonstrated that the non-target stimulus processing was an active process and was related to working memory, i.e., the temporary elimination and the retrieval of the response mode which was stored in working memory.
Zhao
Lun
L
Institute of Space Medico-Engineering, Beijing, China. lunzhao@263.net
Wei
Jin-he
JH
D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008568:Memory / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*