Christoph E. Schreiner
Coleman Mem. Lab., W. M. Keck Ctr. for Integrative Neurosci., Dept. of Otolaryngol., Univ. of California, San Francisco, CA 94143-0732
Neurons in primary auditory cortex (AI) of cats and monkeys have a wide range of functional properties that are related to the coding of basic attributes of simple and complex signals. In particular, cortical neurons have been found to be sensitive to the bandwidth of the signal, the spectral energy distribution of broadband stimuli, the overall intensity of the signal, and the temporal sequence of signal elements, in addition to their frequency selectivity and sound localization sensitivity. These response properties appear to be nonuniformly distributed across AI and, thus, create spatially and functionally distinct subregions that may constitute parallel auditory processing streams. Studies with behaviorally trained animals suggest that these functional cortical organizations are not fixed but can undergo changes. This representational plasticity results in more detailed representations of portions of the animal's acoustic environment that have high behavioral relevance. An understanding of the creation, relationships, and interconnections of these different coding properties is essential for the comprehension of the neural code of communication sounds such as speech. [Work supported by the Office of Naval Research, the Human Frontier Science Project, and the Coleman Fund.]