The Event-related Potentials During Imitated Natural Reading

Owing to its high temporal resolution, event-related potential (ERP) technique provides animportant tool to understand the higher cognitive activities of the brain. But in traditional ERP studies, visual stimuli are usually presented to subjects abruptly, which results in the evoked ERPs including cognitive signals produced by cognitive processing of the information carried by the stimuli as well as exogenous brain noises evoked by the physical stimulation of the stimuli. These two kinds of signals are difficult for signal processing technique to separate effectively. Inspired from human natural reading without abrupt stimulation, we imitated natural reading by letting symbol sentences translated relative to the sightline and investigated the exogenous characteristics of the brain under such an imitated natural reading condition. We found that both the head symbol and the end symbol of the sentences evoked exogenous noises, which lasted for a relatively long time, but the symbols presented quasi-persistently in the middle of the sentences did not evoke any noise. Based on such an important characteristic of the brain we developed an event-related potential technique by imitating natural reading, and investigated and compared the target detection effects obtained under the condition without abrupt stimulation with those obtained under the condition with abrupt stimulation through a target searching task. It was found that the target detection effects obtained under two conditions are different. Since the target detection effects can be extracted directly under the condition without abrupt stimulation, suggesting the event-related potential technique by imitating natural reading is a potential tool to study higher cognitive functions of the brain.