Neuronal activation in female budgerigars is localized and related to male song complexity

Abstract

Females of several songbird species have been shown to respond preferentially to a more complex song. The male budgerigar (Melopsittacus undulatus) sings complex songs consisting of discrete components, known as syllables. We exposed female budgerigars to either standard male song, complex song, or simple song, the iteration of only one syllable (either frequency-modulated or unmodulated). Using immunocytochemistry, we analysed the expression of the protein product of the immediate early gene ZENK in a number of forebrain regions. The level of Zenk protein expression caused by song stimuli varied among each of the brain regions. Expression was highest in the caudomedial neostriatum (NCM), lower in the caudomedial hyperstriatum ventrale (CMHV), and lowest in the hippocampus. There was a significant effect of song complexity on the number of Zenk-immunoreactive cells in the NCM, but not in the hippocampus. Zenk protein expression correlated significantly and positively with the number of different syllables to which the females were exposed in the NCM and to a lesser extent in the CMHV, but not in the hippocampus. For the NCM this correlation was also significant within the group exposed to natural song. These results suggest that the NCM is involved in the perception of song complexity in female budgerigars.

Immediate early gene (ZENK, Arc) expression in the auditory forebrain of female canaries varies in response to male song quality

“…In female zebra finches, lesions of CMM lead to a disruption of their song discrimination ability (MacDougall-Shackleton et al, 1998). In a number of studies, although CMM was involved in the integration of song stimuli as well, NCM was the area that showed greater differences in IEG expression (Gentner et al, 2001;Eda-Fujiwara et al, 2003;but see Bailey et al, 2002;Sockman et al, 2002). Both NCM and field L (the primary auditory projection region) have reciprocal connections with CMM, which could lead to a shift in neuronal integration according to different experimental conditions during auditory processing.…”

“…Concerning auditory representation patterns in the avian forebrain, it is important to emphasize that in a number of studies, NCM was subdivided into different subregions, for example, in a dorsal and ventral part (Gentner et al, 2001;Eda-Fujiwara et al, 2003;Maney et al, 2003), in a medial and lateral part (Terpstra et al, 2004), and most interestingly, Ribeiro et al (1998) found a specific pattern of activation within NCM according to different auditory stimuli and even syllables in canaries. Therefore, due to the diversity of applied NCM subdivisions and in light of the previous results found in the canary we found it not advisable to predispose an arbitrary division of NCM for analysis.…”

An Analysis of the Neural Representation of Birdsong Memory

“…It is remarkable that the overall level of Zenk expression is lower in the lateral part of the NCM compared with that in the medial part, whereas the correlation between neuronal activation and percentage of copied elements is significant only in the lateral part of the NCM, although the difference between these two correlations is not very large. Nevertheless, several studies (Gentner et al, 2001;Eda-Fujiwara et al, 2003;Maney et al, 2003) have reported differences in IEG expression between dorsal and ventral parts of the NCM after exposure to conspecific song, although Ribeiro et al (1998) showed that exposure to different auditory stimuli resulted in different activation patterns within the NCM. In an electrophysiological study, Chew et al (1995, their Fig.…”

Topography of estradiol‐modulated genomic responses in the songbird auditory forebrain

“…Gentner et al (2001) introduced the practice of dividing NCM into dorsal and ventral domains by bisecting it orthogonal to its dorso-ventral axis. Since that time, the majority of published studies have followed this convention (e.g., Eda-Fujiwara et al, 2003;Maney et al, 2003;Phillmore et al, 2003;Hernandez and MacDougall-Shackleton, 2004;Avey et al, 2005Avey et al, , 2008Sockman et al, 2005;McKenzie et al, 2006;Tomaszycki et al, 2006;Lynch and Ball, 2008;Sockman and Salvante, 2008;Velho and Mello, 2008). Although many researchers have reported that dorsal and ventral NCM differ in their sensitivity to and selectivity for a variety of experimental stimuli, these domains do not appear to have a cytoarchitectonic, neurochemical, or hodological basis.…”