title: Brain mechanisms underlying visual perception and visual mental imagery of Chinese pseudo-characters: an event-related potential study.
abstract: The aim of this study was to compare spatiotemporal cortical activation patterns that underlie the processing of visual perception and visual mental imagery of Chinese pseudo-characters. Event-related brain potentials (ERPs) were measured when 14 healthy Chinese college students performed a pseudo-character stroke judgment task. Results showed that visual mental imagery elicited a more negative ERP deflection (N240) than visual perception in the 150- to 250-ms time window after onset of the stimuli. Maps of the difference wave (mental imagery-visual perception) showed strong activity in the right frontal regions. Dipole analysis revealed that the generator of N240 was localized in the right parahippocampal cortex and possibly related to forming a visual mental imagery of the pseudo-character on the basis of initial stimuli identification and classification. Then in the time window between 400 and 600 ms, a greater negativity (N520) in visual mental imagery as compared to visual perception was detected over the right frontocentral scalp regions. Moreover, dipole source analysis of the difference wave (mental imagery-visual perception) indicated that a generator was localized in the right temporal-occipital junction (BA18), which appeared to reflect the cognitive processes of character reconstruction and stroke searching in the visual mental imagery of the pseudo-character. The results showed that the visual mental imagery of Chinese pseudo-characters might be related to the right parahippocampal cortex, and activation of the right temporal-occipital junction was possibly related to accomplishing the stroke judgment task in the visual mental imagery.
authors.affiliation: School of Psychology, Southwest University, Key Laboratory of Cognition and Personality (SWU), Ministry of Education, Beibei, Chongqing, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Qiu
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
authors.forename: Qinglin
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*