The Program Project is focused upon detailed analyses of the structure and function of the primary auditory area of the cerebral cortex. The ultimate goal of the research is to reveal the physiological, anatomical and pharmacological determinants of the processing of monaural and binaural acoustic stimuli in the auditory cortex. The research program consists of five projects, each focused upon a different aspect of cortical function, with project, however, being strongly dependent upon the research conducted in other projects. In addition to sharing the information generated by each of the projects, each depends to a very great extent upon the expertise of each member of the program. 1. The development of auditory cortex will be studied by analyzing the growth of the cortex and its afferent sources in vivo and in vitro and the molecular determinants of its growth. 2. The physiology of auditory cortex will be studied at the level of the single neuron both extracellularly and intracellularly with the goals of understanding the synaptic mechanisms that shape its responses to monaural and binaural acoustic stimuli. 3. The anatomy of auditory cortex will be studied at both the light and electron microscopic levels to understand the intricate architectural features of the cortical circuitry, the afferent sources of this circuitry and the pathways within the cortex that convey information from one area to another. 4 The chemical anatomy of auditory cortex will be studied using the techniques of receptor binding, in situ hybridization, and immunohistochemistry with the goal of defining the chemical interactions between neuron which, ultimately, determine our ability to hear. By revealing the developmental, physiological, anatomical and chemical determinants of auditory cortex function, we should be closer to understand how we hear. Such information is crucial to the clinical treatment of hearing impairment.