Shamma, S.A.Vranic, S.Wiser, P.Mapping of the spatial distribution of responses in the primary auditory cortex (AI) reveal that both the gradient of the acoustic spectrum and sensitivity to FM sweep direction are encoded in an orderly manner along the isofrequency planes of AI. Psychoacoustical tests also demonstrate a potential perceptual correlate of the gradient maps, namely the threshold stability and heightened sensitivity of human subjects to the detection of changes in the symmetry of spectral peaks.en-USneural systemsspeech processingspectral gradientsFM selectivityspectral shapesymmetrybandwidthCommunicationSignal Processing SystemsTechnical Report