The neural basis of spatial processing in the auditory cortex has been controversial. Human fMRI studies suggest that a part of the planum temporale (PT) is involved in auditory spatial processing, but it was recently argued that this region is active only when the task requires voluntary spatial localization. If this is the case, then this region cannot harbor an ongoing spatial representation of the acoustic environment. In contrast, we show in three fMRI experiments that a region in the human medial PT is sensitive to background auditory spatial changes, even when subjects are not engaged in a spatial localization task, and in fact attend the visual modality. During such times, this area responded to rare location shifts, and even more so when spatial variation increased, consistent with spatially selective adaptation. Thus, acoustic space is represented in the human PT even when sound processing is not required by the ongoing task.
Bibliographical noteFunding Information:
The study was conducted at the Henry H. Wheeler Jr. Brain Imaging Center at the University of California at Berkeley and at the Asher Center for Human Imaging of the Weizmann Institute in Israel, and we are grateful for the staff of these centers for their help. We wish to thank Dr. Ben Inglis, PhD, for help in constructing the MRI sequences; Rick Redfern for his help with the acoustic setup at the scanner; and Vikas Rao for his help in pilot studies for this project in Berkeley. We also thank Dr. Talma Handler for her support. This work has been supported by NINDS Grant NS21135 to R.T.K. and an Israel Science Foundation grant 477-05 to L.Y.D.