Neural systems involved in spatial discrimination based on viewer- and object-centered reference frames; A study  using the LORETA analysis of event-related potentials

Yuriko Kiriyama1-4,  Katsumi Umeno1-3, Etsuro Hori1-3, Yang Li1,2,  Nobuyuki Sunahara4, Taketoshi Ono1-3,  Hisao

Nishijo1-3

ABSTRACT

Event-related potentials (ERPs)  were recorded  while the subjects detected  defective parts of circles, presented  on a monitor, based  on the viewer- and object-centered  reference frames. These figures elicited the ERPs mainly at the parietal areas.  A sLORETA  analysis of the ERPs indicated that current source density (CSD) was higher at the dominant  right parietal  lobe  in the both  tasks based  on the viewer- and  object-centered reference frames. Furthermore, CSD was higher at the superior frontal and  superior temporal  gyri only in the object-centered   reference  frame  task.  The  results,  along  with the  previous  anatomical   data,   suggest  an involvement of the dorsal  visual pathways in the viewer-centered reference  frame while the both dorsal  and ventral visual pathways might be involved in the object-centered  reference frame. These results further suggest that the both visual pathways might converge on the right dominant parietal lobe.

Key words: Spatial hemineglect,  spatial  discrimination task, event-related  potentials,  current source  density, parietal lobe.