Brain mechanisms underlying visual perception and visual mental imagery of Chinese pseudo-characters: an event-related potential study

Brain Res. 2007 Dec 12:1184:202-9. doi: 10.1016/j.brainres.2007.09.068. Epub 2007 Oct 4.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Brain Mapping*
  • Electroencephalography
  • Evoked Potentials, Visual / physiology*
  • Female
  • Functional Laterality
  • Humans
  • Imagination / physiology*
  • Male
  • Pattern Recognition, Visual / physiology*
  • Photic Stimulation / methods
  • Time Factors
  • Visual Cortex / physiology*