Functional organization of spectral receptive fields in the primary auditory cortex of the owl monkey

Recent experiments in the cat have demonstrated that several response param eters, including frequency tuning, intensity tuning, and FM selectivity, ar e spatially segregated across the isofrequency axis. To investigate whether a similar functional organization exists in the primate, we have studied t he spatial distribution of pure-tone receptive field parameters across the primary auditory cortex (AI) in six owl monkeys (Aotus trivirgatus). The di stributions of binaural interaction types and onset latency were also exami ned. Consistent with previous studies, the primary auditory cortex containe d a clear cochleotopic organization. We demonstrate here that several other properties of the responses to tonal stimuli also showed nonrandom spatial distributions that were largely independent from each other. in particular , the sharpness of frequency tuning to pure tones, intensity tuning and sen sitivity, response latency, and binaural interaction types all showed spati al variations that were independent from the representation of characterist ic frequency and from each other. Statistical analysis confirmed that these organizations did not reflect random distributions. The overall organizati onal pattern of overlaying but independent functional maps that emerged was quite similar to that seen in Al of cats and, in general, appears to refle ct a fundamental organization principle of primary sensory cortical fields. (C) 1999 Wiley-Liss, Inc.