The main aim of this research is to determine how auditory space is encoded in the brain. The study attempts to establish direct links between behavioral, neurophysiological, and neuroanatomical observations. The results obtained so far indicate that the barn owl offers an excellent model for the discovery of those links. The owl's auditory system resembles the auditory system of mammals in several important aspects. The owl's midbrain auditory nucleus contains a neural map of auditory space. The cellular components of the map are space-specific neurons, which respond only to sound emanating from a restricted area in space. The space-selectivity of these neurons is due to their tuning to a narrow range of interaural time and intensity differences. These binaural cues are processed independently in two separate channels within the auditory brainstem. The proposed research attempts to obtain behavioral evidence for the separation of the channels. The first site of neuronal tuning to interaural time differences is nucleus laminaris. The tuning is due to the detection of coincidence between the inputs from the left and right cochlear neuclei. The coincidence detection involves neuronal delay lines, which are systematically arranged as a map of delays. The proposed research tries to discover the cellular basis of the delay lines, the conditions for coincidence detection, the projection of the map of delays to higher centers, and the first site of neuronal tuning to interaural intensity differences.
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