New brain pathways found in the vocal control system of a songbird

Abstract

Songbirds use a complex network of discrete brain areas and connecting fiber tracts to sing their song, but our knowledge of this circuitry may be incomplete. The forebrain area, "caudal mesopallium" (CM), has received much attention recently for its song-related activities. HVC, a prominent song system nucleus, projects to a restricted area of the CM known as the avalanche nucleus (Av). However, the other connections of Av remain unknown. Here we used tract-tracing methods to examine the connections of Av to other song system nuclei. Injections of biotinylated dextran amine (BDA) into Av labeled both afferent terminals and neurons in HVC and the interfacial nucleus of the nidopallium (NIf), suggesting that there is complex feedforward and feedback communication between these nuclei (HVC<-->Av<-->NIf). Labeled neurons were also found in the uvaeform nucleus (Uva), which was substantiated by BDA injections into Uva that labeled terminals in Av. Double fluorescent tracing experiments confirm that both HVC and Uva project to Av. The present study adds complex new connections that expand the traditional song system circuitry into the caudal mesopallium. These new pathways are likely to have broad implications for deciphering how this intricate system works.

Regulation of learned vocal behavior by an auditory motor cortical nucleus in juvenile zebra finches

“…Adult song is produced mainly by HVC, as shown by lesion, cooling, and single-unit recording experiments (Aronov et al 2008;Hahnloser et al 2002;Long and Fee 2008). However, less understood are premotor or sensory areas feeding into HVC such as the thalamic nucleus uvaeformis (Uva), the nucleus interface of the nidopallium (NIf), the medial magnocellular nucleus of the anterior nidopallium (MMAN), and the nucleus avalanche (AV) (Akutagawa and Konishi 2010;Foster et al 1997). Here we investigated a possible premotor involvement of the cortical NIf.…”

Birdsong memory and the brain: In search of the template

“…2B) within the auditory caudal mesopallium (of which the CMM is the more medially located part) that is activated when the bird sings, but not when it hears song (Nottebohm et al, 1982;Jarvis and Nottebohm, 1997), with the exception of BOS (Akutagawa and Konishi, 2010). Nucleus Av is connected to NIf and HVC (Akutagawa and Konishi, 2010). It is plausible that these neural 'enclaves' play a role in the exchange of information between the two major networks involved in song learning.…”

Advances in Understanding the Auditory Brain of Songbirds

“…A weak projection exists from Ov shell to CM (Vates et al, 1996). Further, a restricted area within the caudal ventral mesopallium, known as the avalanche nucleus (Av; Akutagawa & Konishi, 2010) has a reciprocal connection with HVC. Av was first identified by Nottebohm and colleagues in canaries (Nottebohm et al, 1982) and has since been implicated in the song control system (Jarvis & Nottebohm, 1997;Jarvis, 2007).…”

“…Av was first identified by Nottebohm and colleagues in canaries (Nottebohm et al, 1982) and has since been implicated in the song control system (Jarvis & Nottebohm, 1997;Jarvis, 2007). Because neurons in Av have been reported to display BOS-selective responses (Akutagawa & Konishi, 2010), this nucleus may constitute a pathway for auditory information to reach HVC.…”