Abstract
Diverse dopamine (DA) pathways send distinct reinforcement signals to different striatal regions. In adult songbirds, a DA pathway from the ventral tegmental area (VTA) to Area X, the striatal nucleus of the song system, carries singing-related performance error signals important for learning. Meanwhile, a parallel DA pathway to a medial striatal area (MST) arises from a distinct group of neighboring DA neurons that lack connectivity to song circuits and do not encode song error. To test if the structural and functional segregation of these two pathways depends on singing experience, we carried out anatomical studies early in development before the onset of song learning. We find that distinct VTA neurons project to either Area X or MST in juvenile birds before the onset of substantial vocal practice. Quantitative comparisons of early juveniles (30–35 days post hatch), late juveniles (60–65 dph), and adult (>90 dph) brains revealed an outsized expansion of Area X-projecting neurons relative to MST-projecting neurons in VTA over development. These results show that a mesostriatal DA system dedicated to social communication can exist and be spatially segregated before the onset of vocal practice and associated sensorimotor experience.
Funder
National Institute of Neurological Disorders and Stroke
Publisher
Public Library of Science (PLoS)
Reference42 articles.
1. Behavioral dopamine signals;W. Schultz;Trends Neurosci,2007
2. Adaptive critics and the basal ganglia.;AG Barto;Models of information processing in the basal ganglia,1995
3. A neural network model with dopamine-like reinforcement signal that learns a spatial delayed response task;RE Suri;Neuroscience,1999
4. A neural substrate of prediction and reward;W Schultz;Science,1997
5. Multiple Dopamine Systems: Weal and Woe of Dopamine;M Watabe-Uchida;Cold Spring Harb Symp Quant Biol,2018