Transformation of temporal sequences in the zebra finch auditory system.

Yoonseob Lim,Timothy J Gardner,Ryan Lagoy,Barbara G Shinn-Cunningham

doi:10.7554/elife.18205

Abstract

This study examines how temporally patterned stimuli are transformed as they propagate from primary to secondary zones in the thalamorecipient auditory pallium in zebra finches. Using a new class of synthetic click stimuli, we find a robust mapping from temporal sequences in the primary zone to distinct population vectors in secondary auditory areas. We tested whether songbirds could discriminate synthetic click sequences in an operant setup and found that a robust behavioral discrimination is present for click sequences composed of intervals ranging from 11 ms to 40 ms, but breaks down for stimuli composed of longer inter-click intervals. This work suggests that the analog of the songbird auditory cortex transforms temporal patterns to sequence-selective population responses or 'spatial codes', and that these distinct population responses contribute to behavioral discrimination of temporally complex sounds.

Highlights

IntroductionThe core of the auditory processing system consists of anatomical areas named Field L, NCM (caudomedial nidopallium), and CM (caudomedial mesopalium) (Vates et al, 1996) (Figure 1c)
A highly developed auditory network supports auditory-vocal behavior in songbirds
When the stimulus set was slowed by a factor of two, the strength of the temporal to spatial transformation in the secondary auditory was reduced, and there was a corresponding degradation of behavioral discrimination. These results indicate that the ascending auditory pathway in zebra finches transforms temporal sequences into distinct population vectors

Summary

Introduction

The core of the auditory processing system consists of anatomical areas named Field L, NCM (caudomedial nidopallium), and CM (caudomedial mesopalium) (Vates et al, 1996) (Figure 1c). These areas and other associated auditory areas are directly and indirectly connected with the song motor pathway (Vates et al, 1996; Mandelblat-Cerf et al, 2013). These hierarchically and reciprocally connected auditory areas are thought to be analogous to the early stages of mammalian auditory cortex, but the details of the homologies remain a subject of debate (Jarvis et al, 2005; Wang et al, 2010; Calabrese and Woolley, 2015)

Methods

Results

Conclusion