The Stability Of Event-related Potential N270 And Its Clinical Application

Experiment 1: The event-related potentials elicited by spatial location conflict in human brainObjective: To explore the processing mechanism of human brain for spatial location conflicts.Method: sixteen normal adults participated in the matching-to-sample task. They were asked to discriminate if the position of the two visual stimulus presented in sequence were identical and event-related potential (ERP) was recorded from their scalp.Results: ERP components of P100, N150, LPC (late positive component) and SNW (slow negative wave) were recorded in condition 1; in condition 2, N150 was enhanced and N270 was elicited before LPC. N150, N270 and SNW were all mainly distributed bilaterally at posterior areas.Conclusion: N270 can be elicited by spatial location conflict. It represents the brain activity for processing spatial discrepancy.Experiment 2(1): The stability of Event-related potential N270 in color matching taskObjective: The present study examined long-term repetition effects on human event-related potential N270 in color matching task.Method: Eighteen subjects performed a color matching task while event-related potentials (ERPs) were recorded from their scalp and the recording was repeated after six months. There were two kinds of stimulus pairs in this study: match condition, the second stimulus (S2) in a pair was identical to the first one (SI); conflict condition, S2 conflicted with SI in the color attribute. Subjects were required to press a button in the match condition and another button in the conflict condition.Results: A negative ERP component, N270, which was considered to reflect the conflict processing activity in . human brain, was evoked by the S2 of conflict condition in two tests. The repeated test showed a delayed and enhanced P300 than the first test. The amplitude of N270 elicited in the conflict condition was enhanced in the repeated test at C3, C4 and P3 electrodes but its latency did not differ from the first test.Conclusion: The peak latency of N270 is much stable than that of P300 in color matching task. N270 can be used as a reliable method to evaluate the cognitive ability.,Experiment 2 (2) : The stability of Event-related potential N270 in shape discrimination taskObjective: The present study examined long-term repetition effects on human event-related potential N270 in shape discrimination task.Method: Fifteen subjects participated in this study.There are two kinds of stimulus pairs in this study: condition 1, the second stimulus (S2) in a pair was identical to the first one (S1) in shape attribute (match condition); condition 2, S2 conflicted with S1 in their shape attribute (conflict condition). Subjects were instructed to press a button in the match condition and another button in the conflict condition, and event-related potentials (ERPs) were recorded from their scalp. The test was repeated six months later.Results: The N270 component was evoked by S2 of the conflict condition rather than the match condition in both of the two tests. The amplitude of N270 is enhanced in the repeated test.Conclusion: N270 is much stable in shape discrimination task. Because of the study effect, the conflict processing system started earlier than the first test.Experiment 3: Event related potential N270 in detecting cognitive impairment of transient ischemic attackObjective: To find the cognitive impairments in patients with transient ischemic attack (TIA) and to verify the feasibility of N270 as a clinical examination method to evaluate the cognitive state of TIA patients.Method: Stimulus pairs with identical (match condition) or different (conflict condition) colors were randomly presented to subjects. Thirty TIA patients without clinical dementia and thirty age-matched control subjects determinedif the two stimuli in a pair had the same color while ERPs were recorded from their scalps.Results: N270 was evoked by the S2 of the conflict condition in either controls or patients. The patient group exhibited a delaye...