Neural Correlates of Auditory Streaming of Harmonic Complex Sounds with 2

197 words) 27 It has been suggested that successively presented sounds that are perceived as separate 28 auditory streams are represented by separate populations of neurons. Mostly, spectral 29 separation in different peripheral filters has been identified as the cue for segregation. 30 However, stream segregation based on temporal cues is also possible without spectral 31 separation. Here we present sequences of ABAtriplet stimuli providing only temporal 32 cues to neurons in the European starling auditory forebrain. A and B sounds (125ms 33 duration) were harmonic complexes (fundamentals 100, 200 or 400 Hz; center 34 frequency and bandwidth chosen to fit the neurons' tuning characteristic) with identical 35 amplitude spectra but different phase relations between components (cosine, alternating 36 or random phase) and presented at different rates. 37 Differences in both rate responses and temporal response patterns of the neurons when 38 stimulated with harmonic complexes with different phase relations provide first 39 evidence for a mechanism allowing a separate neural representation of such stimuli. 40 Recording sites responding above 1 kHz showed enhanced rate and temporal 41 differences compared to those responding at lower frequencies. These results 42 demonstrate a neural correlate of streaming by temporal cues due to the variation of 43 phase that shows striking parallels to observations in previous psychophysical studies. 44 45