Songbirds learn vocalizations by hearing and practicing songs. As song develops, the tempo becomes faster and more precise. In the songbird brain, discrete nuclei form interconnected myelinated circuits that control song acquisition and production. The myelin sheath increases the speed of action potential propagation by insulating the axons of neurons and by reducing membrane capacitance. As the brain develops, myelin increases in density, but the time course of myelin development across discrete song nuclei has not been systematically studied in a quantitative fashion. We tested the hypothesis that myelination develops differentially across time and song nuclei. We examined myelin development in the brains of the zebra finch (
The thalamostriatal system is a major network in the mammalian brain, originating principally from the intralaminar nuclei of thalamus. Its functions remain unclear, but a subset of these projections provides a pathway through which the cerebellum communicates with the basal ganglia. Both the cerebellum and basal ganglia play crucial roles in motor control. Although songbirds have yielded key insights into the neural basis of vocal learning, it is unknown whether a thalamostriatal system exists in the songbird brain. Thalamic nucleus DLM is an important part of the song system, the network of nuclei required for learning and producing song. DLM receives output from song system basal ganglia nucleus Area X and sits within dorsal thalamus, the proposed avian homolog of the mammalian intralaminar nuclei that also receives projections from the cerebellar nuclei. Using a viral vector that specifically labels presynaptic axon segments, we show in Bengalese finches that dorsal thalamus projects to Area X, the basal ganglia nucleus of the song system, and to surrounding medial striatum. To identify the sources of thalamic input to Area X, we map DLM and cerebellar‐recipient dorsal thalamus (DTCbN). Surprisingly, we find both DLM and dorsal anterior DTCbNadjacent to DLM project to Area X. In contrast, the ventral medial subregion of DTCbNprojects to medial striatum outside Area X. Our results suggest the basal ganglia in the song system, like the mammalian basal ganglia, integrate feedback from the thalamic region to which they project as well as thalamic regions that receive cerebellar output.
more » « less- NSF-PAR ID:
- 10056108
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Comparative Neurology
- Volume:
- 526
- Issue:
- 9
- ISSN:
- 0021-9967
- Page Range / eLocation ID:
- p. 1550-1570
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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