Fig. 1.

Top: parasagittal schematic at ∼0.5 mm lateral to midline showing location of caudo-medial nidopallium (NCM) in caudal telencephalon. Black dots represent the location of 8 representative recording sites (n = three adults, three 35-day-old and two 20-day-old birds) in a small area encompassing the most dorso-caudal region of NCM; all recording sites within this region showed robust habituation to song playback. CM, caudal mesopallium; LaM, mesopallial lamina; PSL, pallial-subpallial lamina; D, dorsal; V, ventral; P, posterior; A, anterior. Bottom: response habituation for a single recording site in NCM. Examples from an adult bird of response strength during 20 iterations of tutor song (TUT; triangles) and unfamiliar conspecific song (unfamCON; diamonds), normalized to the first trial, are shown. The slope of the linear regression of these normalized functions was used as a measure of the rate of habituation that could be compared across birds and song types.