Abstract: Zebra finches are social animals that communicate via different types of vocalizations, and their song system is an ideal model for studying sensorimotor learning. Throughout adulthood, new neurons are added continuously into the telencephalic brain structure HVC (proper name), which is heavily involved in motor control of singing. The role of these adult-born new HVC neurons is unclear: they express immediate early genes following singing, which indicates some involvement in song production, yet controversially, there are no new acoustic elements added to zebra finches’ songs once they are learned from the tutor, unlike canaries which learn new songs seasonally. Approximately half of these adult-born HVC neurons are known to project to the robust nucleus of the arcopallium (RA), but the other half cannot and their identity has remained a mystery. However, recent studies in the Aaron lab showed that about 50% of the adult-born HVC neurons express DARPP-32, a phosphoprotein associated with dopamine receptor expression, and it’s exclusive to the 50% of new neurons that do not backfill from RA. Zebra finch songs can be roughly divided into two types based on the social scenario: female-directed songs and undirected songs. In general, the female-directed songs are longer and acoustically more stereotyped than their undirected counterparts. There is a dopaminergic projection from the periaqueductal gray (PAG) to HVC, and it appears to signal the social context for the production of directed songs. Lesioning DAergic terminals in HVC eliminates directed singing, and lesioning PAG eliminates all female-directed mating behaviors. The goal of our project is to determine whether the DARPP-32+ adult-born HVC neurons receive dopaminergic inputs from the PAG by injecting an anterograde tracer into PAG and seeing whether labeled DAergic terminals are found on DARPP-32+ adult-born HVC neurons. During this summer, we have worked to identify the stereotaxic injection coordinates for PAG. In the near future, we plan on modifying these coordinates to make the surgeries survivable, in order to allow time for the tracer to get transported into the axon terminals at HVC.
Zoom link: https://wesleyan.zoom.us/j/99443973421?pwd=bGFaMXprMGJ2b0RrSyszVFMxbG05UT09
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