Departments of Biology and Otolaryngology, University of Washington, Seattle, Washington 98195-6515, USA
Address for correspondence: David J. Perkel, Departments of Biology and Otolaryngology, Box 356515, University of Washington, Seattle, WA 98195-6515. Voice: 206-221-2477; fax: 206-543-5152.
perkel{at}u.washington.edu;
http://faculty.washington.edu/perkel
Ann. N.Y. Acad. Sci. 1016: 736-748 (2004).
The brain nuclei and pathways comprising the song system of
oscine songbirds bear many similarities with circuits in other
bird species and in mammals. This suggests that the song system
evolved as a specialization of pre-existing circuits and may
retain fundamental properties in common with those of other
taxa. Here we review evidence for these similarities, including
electrophysiological, morphological, and neurochemical data
for identifying specific cell types. In addition, we discuss
connectional data, addressing similarities in axonal projections
among nuclei across taxa. We focus primarily on the anterior
forebrain pathway, a circuit essential for song learning and
vocal plasticity, because the evidence is strongest that this
circuit is homologous to mammalian circuits. These fundamental
similarities highlight the importance of comparative approaches;
for example, understanding the role the anterior forebrain pathway
plays in song plasticity may shed light on general principles
of basal ganglia function. In addition, understanding specializations
of such circuits in songbirds may illuminate specific innovations
critical for vocal learning.
