Temporal stream of cortical representation for auditory spatial localization in human hemispheres

We measured human evoked magnetic fields to binaural sounds with an interau ral time delay as a cue for auditory localization. By analyzing the topogra phy of auditon/-evoked magnetic fields in the middle-latency, we demonstrat ed that particular cortical regions represent the direction of sound locali zation by their activity level. Upon presenting a binaural sound, the first representations were found in the middle frontal region as well as the sup erior temporal region of the right hemisphere approximately 19 ms after the stimulation, but their patterns differed. Other cortical regions including the prefrontal and parietal spatial areas were affected within roughly 60 ms. The results showed that the right hemisphere is dominant even in the pr eattentive stage of auditory spatial processing of sounds from different di rections. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.