Sexual dimorphism in song-induced ZENK expression in the medial striatum of juvenile zebra finches

Abstract

In the brains of male zebra finches (Taeniopygia guttata), the nuclei that direct song learning and production are larger than the corresponding regions in females, who do not sing. The dimorphism in Area X of the medial striatum (MSt), an area important for song learning, is even more dramatic in that it is identifiable in males but not females by Nissl stain. In the present study, conspecific song, but not other auditory stimuli, induced expression of the immediate early gene ZENK in the MSt surrounding but not within Area X in juvenile males (30 and 45 days post-hatch). ZENK immunoreactivity following conspecific songs was homogeneous throughout the MSt of females at the same ages. Little to no FOS immunoreactivity was observed in Area X or the rest of the MSt, and levels were not influenced by the type of auditory stimulus presented. Thus, the clear morphological difference in the lateral MSt (Area X) of males and females is mirrored by a specific functional one, and the data suggest a role for ZENK expression in the MSt outside of Area X in responding to relevant song stimuli. KeywordsSong perception; Immediate early gene; Area X; Basal ganglia; Song learning; Sex difference Nottebohm and Arnold [23] first described dramatic sexual dimorphisms in the brains of adult zebra finches and canaries wherein regions that control song learning and production are larger in males that sing than in females that do not. One of these regions, Area X of the medial striatum (MSt), is not identifiable via Nissl stains in females. Area X plays an integral role in male song learning and possibly song production in adulthood. For example, juvenile males with Area X ablated produce abnormal song in adulthood, although in adult males lesions of the nucleus have no detectable effect on song production or quality [26,31]. Interestingly, neurons in Area X show singing-related electrophysiological activity that declines slowly after song stops being produced [11], suggesting a function for the region outside of the sensitive period for song learning. Cells in this region in both juveniles and adults also display longterm potentiation [7]. In birds that hear song and sing in response, ZENK expression is increased in Area X compared to birds that hear song only or birds that hear no song [13][14][15]24]. Additionally, when the tracheosyringeal nerve is axotomized in developing males, the electrophysiological activity of some neurons within Area X is then tuned to the abnormal, axotomized bird's own song as well as the tutor's song, suggesting that neurons within Area X are important for vocal practice [32]. In males, the Nissl-defined volume of Area X increases between d10 and d40, when the adult volume is reached [20], and this change in volume is due in part to the addition of neurons during that period in males but not females [16,21].While it is clear that Area X is highly sexually dimorphic and important for the development of song in males, it was unknown whether the corresponding lateral region of MSt in females is resp...

Increased Fos expression among midbrain dopaminergic cell groups during birdsong tutoring

“…Finally, we examined Area X for the presence of Fos+ cells because previous work has shown that brief song tutoring promotes the phosphorylation of calcium ⁄ calmodulin-dependent protein kinase II within this striatal ⁄ pallidal region of the song system (Singh et al, 2005). Very few Fos+ cells were present in Area X, even in birds that were tutored by a familiar adult male (data not shown), in agreement with previous studies reporting a lack of song-induced Fos expression within Area X (Kimpo & Doupe, 1997; Bailey & Wade, 2006).…”

“…, 2005). Very few Fos+ cells were present in Area X, even in birds that were tutored by a familiar adult male (data not shown), in agreement with previous studies reporting a lack of song‐induced Fos expression within Area X (Kimpo & Doupe, 1997; Bailey & Wade, 2006).…”

Arrhythmic Song Exposure Increases ZENK Expression in Auditory Cortical Areas and Nucleus Taeniae of the Adult Zebra Finch

“…These results expand on previous data from our lab in juvenile males in which conspecific and heterospecific song, as well as tones, induced a significantly lower density of ZENK labeled cells in Area X than in the medial striatum [81]. In contrast, labeling was uniform throughout the striatum in young females [81]. The current study found a difference between lateral and medial striatum in females as well as males indicating that differences in these areas in females may develop as animals get closer to maturity.…”

The sexually dimorphic expression of L7/SPA, an estrogen receptor coactivator, in zebra finch telencephalon

“…L7/SPA enhancing the actions of estradiol and estrogen receptor-a in the brain is a plausible mechanism on how male zebra finch are able to produce the increased estrogenic signal needed to produce a typically male brain (Nordeen et al, 1987;Grisham et al, 1994;Arnold, 1997a,b). A number of genes have been found to be sexually dimorphic in zebra finch song nuclei, however the functional sig-nificance of many have yet to be determined (Bailey and Wade, 2003;Chen et al, 2005;Kim and Arnold, 2005;Wade et al, 2005;Bailey and Wade, 2006). Future experiments looking into the functionality of L7/SPA are necessary to confirm our hypothesis about the role of L7/SPA on sexual differentiation of zebra finch brain.…”