Fig. 1.
Schematics of the song circuit and LMAN.A, The VMP (white) used in singing includes HVc, RA, nAM, the vocal motoneurons in nXIIts, and respiratory premotor neurons in nAM and nRAm. The AFP (gray) used in auditory-dependent song development as well as in adult song maintenance includes area X, DLM, and LMAN. Auditory areas presynaptic to HVc include Ov, field L, and NIf (dotted); the dashedline indicates abbreviated ascending auditory structures. B, The diagram of LMAN′s intrinsic and extrinsic connections shows the experimental protocol. LMAN contains projection neurons (PN) that innervate area X and RA and GABAergic interneurons (IN) that innervate these projection neurons; both cell classes receive excitatory input from DLM and other LMAN projection neurons. Intracellular recordings were made from LMAN projection neurons while delivering auditory stimuli (“song”). In some experiments, GABAA receptor antagonists or GABA were applied to LMAN via a puffer pipette positioned immediately dorsal to the nucleus.DLM, Dorsolateral part of the medial thalamus;HVc (used as a proper name); L, field L;LMAN, lateral magnocellular nucleus of the anterior neostriatum; nAM, nucleus ambigualis;NIf, nucleus interfacialis; nRAm, nucleus retroambigualis; nXIIts, tracheosyringeal portion of the hypoglossal nucleus; Ov, nucleus ovoidalis;RA, robust nucleus of the archistriatum;X, area X.