Songbird brain circuitry
This diagram represents a sagittal section (as if you are looking at the right ear, with the beak to the right and the back of the head to the left) of a generalized songbird brain, showing the circuits that are known to be involved in learning and singing a male zebra finch's song.
The song output pathway (Uva - NIf - HVc - RA - DM - nXIIts -NXIIts; shown in blue) controls the vocal organ, or syrinx. Lesioning this pathway in adult or in juvenile males affects the song.
A connection from DM to the ventrolateral medulla and thence to nXIIts (shown in green) is presumed to have a role in coordinating the respiratory activity required for song production.
The recursive loop (shown in red) connects HVc to RA via area X, DLM, and lateral MAN, and is recursive because to the collateral projection from LMAN to area X. Lesions to nuclei within the recursive loop affect song development but not the production of adult song.
Two nuclei that are known to be connected to the song system but are not well understood are medial MAN, which sends its output to HVc, and AVT, which is the source of dopamine within area X.
The technical names of components of the song system are: AVT = area ventralis of Tsai; DLM = dorsolaterall division of the medial thalamus; DM = dorsomedial subdivision of the intercollicular nucleus; field L = primary projection of the thalamic auditory relay nucleus; HVc = Hyperstriatum Ventralis pars caudalis (actually part of the neostriatum); LMAN = lateral nucleus magnocelularis of the anterior neostriatum; MMAN = medial nucleus magnocelularis of the anterior neostriatum; NCM = caudo- medial nucleus of the neostriatum; NIf = interfacial nucleus of the neostriatum; nXIIts = the tracheosyringeal division of the twelfth nucleus; NXIIts = the tracheosyringeal portion of the twelfth cranial nerve (= tracheosyringeal nerve); RA = nucleus robustus of the archistriatum; shelf = auditory shelf region underlying HVc; Uva = nucleus uvaeformis of the thalamus; VL medulla = ventrolateral medulla; X = area X of the paraolfactory lobe.
This diagram and its explanation is compiled from work done by Fernando Nottebohm, Tegner Stokes, Christiana Leonard, Darcy Kelley, John Paton, Yoshi Okuhata, Saito, Art Arnold, Sarah Bottjer, Elizabeth Miesner, Masakazu Konishi, Jim McCasland, Constance Scharff, Kathy Nordeen, Ernie Nordeen, Farida Sohrabji, Ed Vates, David Vicario, Martin Wild, and Heather Williams.
This is a web page from the Biology Dept at Williams College, Massachusets
Another external page about song learning is at this address (University of Illinois, Urbana-Champaign)