Local structure sensitivity in auditory information processing in avian song nuclei

Abstract

Birdsong is an excellent research model for sound sequences consisting of complex structures. Neural and behavioral experiments have shown that auditory feedback is necessary for songbirds, especially Bengalese finches, to maintain the quality of the songs and that the nucleus HVC (used as proper name) and the anterior forebrain pathway (AFP) in the nervous system play key roles in this maintenance process. Neurons in the HVC and AFP exhibit higher spike rate to the bird’s own song (BOS) than to other sound stimuli, such as temporally reversed song. To systematically evaluate what aspects of the BOS are captured by the different types of neural activities, both average spike rate and trial-to-trial spike timing variability in the BOS-selective neurons in the HVC and Area X (used as proper name), a gateway to the AFP from the HVC, were investigated following the presentation of auditory stimuli consisting of the BOS with systematic temporal inversion. Within-subjects analysis of the average spike rate and spike timing revealed that neural activity in the HVC and Area X is more sensitive to the local sound modulation of songs than to the global amplitude modulation. In addition, neurons in the HVC exhibit greater consistency of spike timing than neurons in Area X.