Modulation of singing-related gene expression by social context in diencephalon and midbrain cholinergic nuclei
Résumé
Birdsong may have several functions as a communicative signal. Zebra finches?produce acoustically similar songs while alone (undirected) and to female birds (directed). Recent studies have shown that the level of neural activity and of expression of the immediate early gene egr-1 in the anterior forebrain (AF) nuclei LMAN and Area X are much higher during undirected than directed singing. To investigate possible sources of this modulation, we examined singing-related gene expression in the medial Habenula (Hb) and interpeduncular (IPN) nuclei. Consistently there is an opposite pattern of expression in these nuclei, compared to AF nuclei; a high level of egr-1 expression is seen only after directed singing. Furthermore, expression is stronger in limited subregions of IPN, in a pattern suggesting that the synaptic inputs from MHb to IPN may be lateralized. We are combining anterograde tracer injection into left and right MHb with egr-1 expression after courtship singing to test this possiblility. As a possible behavioral source of such lateralization, in initial behavioral results 4 of 5 birds tested viewed the female during initial courtship preferentially with the right eye.