a population rate code of auditory space in the human cortex人口率人类大脑皮层听觉空间的代码.pdfVIP

A Population Rate Code of Auditory Space in the Human Cortex 1,3 1,3 2 1,3 Nelli H. Salminen *, Patrick J. C. May , Paavo Alku , Hannu Tiitinen 1 Department of Biomedical Engineering and Computational Science, Helsinki University of Technology, Helsinki, Finland, 2 Department of Signal Processing and Acoustics, Helsinki University of Technology, Helsinki, Finland, 3 BioMag Laboratory, Hospital District of Helsinki and Uusimaa HUSLAB, Helsinki University Central Hospital, Helsinki, Finland Abstract Background: Previous work on the human auditory cortex has revealed areas specialized in spatial processing but how the neurons in these areas represent the location of a sound source remains unknown. Methodology/Principal Findings: Here, we performed a magnetoencephalography (MEG) experiment with the aim of revealing the neural code of auditory space implemented by the human cortex. In a stimulus-specific adaptation paradigm, realistic spatial sound stimuli were presented in pairs of adaptor and probe locations. We found that the attenuation of the N1m response depended strongly on the spatial arrangement of the two sound sources. These location-specific effects showed that sounds originating from locations within the same hemifield activated the same neuronal population regardless of the spatial separation between the sound sources. In contrast, sounds originating from opposite hemifields activated separate groups of neurons. Conclusions/Significance: These results are highly consistent with a rate code of spatial location formed by two opponent populations, one tuned to locations in the left and the other to those in the right. This indicates that the neuronal code of