Song-related brain auditory activity in Bengalese finches as examined by immediate early gene expressions: Comparison of arousal states and the correlational analyses between brain regions

Abstract

Songbirds use auditory feedback to memorize a tutor song in juveniles and to maintain it in adults. In Bengalese finches, electrophysiological studies showed the auditory responses in the premotor area HVC remained active regardless of asleep/awake status, in contrast to auditory gating phenomenon identified in zebra finches. We investigated the correlations in auditory activity between the brain regions and differences in the activity during wakefulness and sleeping in Bengalese finches. We used the immediate early gene egr-1 as a marker of neural activity that can detect regions responding to auditory stimuli in the whole brain. Results showed that auditory response, as measured by egr-1 expression to the bird's own song while sleeping and awake, was similar in HVC and NCM. Higher activity during awake than sleep was found only in the lower auditory area MLd. Analyses showed egr-1 expressions between brain regions induced by the bird's own song playback in awake/sleep conditions, suggesting that auditory information correlated with the inter part, not the outer part, of MLd with the higher song-related regions. Furthermore, the sleep condition suppressed the spontaneous activity, but not the song-induced activity in Area X. Altogether, this study presents a new attempt to explore the auditory-motor network using a molecular tool to map neurons of the nearly whole brain.

Keywords: Auditory pathways; Bengalese finches; Brain; Immediate early gene; Song learning circuit; Songbirds.