Functional topographies in the primary auditory cortex of the cat.

One of the fundamental organizational principles of the mammalian sensory cortex is the topographic representation of the sensory epithelium. A cochleotopic topographic organization has been demonstrated for a number of auditory cortical fields, including the primary auditory field (AI). In the spatial cortical dimension orthogonal to the cochleotopic frequency gradient, systematic arrangements of other functional parameters have been observed. The first evidence of a spatial segregation of functional parameters along the isofrequency domain of cat AI was the discovery of binaural interaction bands. Recent studies show topographic representations of additional functional parameters in the central auditory system of the cat. Among the functional parameters that are evidence of systematic and topographic representations in cat auditory cortical fields are spectral resolution (sharpness of tuning), temporal resolution (preferred repetition rate), and inhibitory properties related to the coding of broadband signals.