TEMPORAL HIERARCHICAL CONTROL OF SINGING IN BIRDS

Songs of birds comprise hierarchical sets of vocal gestures. In zebra finches, songs Include notes and syllables (groups of notes) delivered in fixed sequences. During singing, premotor neurons in the forebrain nucleus HVc exhibited reliable changes In activity rates whose patter ns were uniquely associated with syllable identity. Neurons in the for ebrain nucleus robustus archistriatalis, which receives input from the HVc, exhibited precisely rimed and structured bursts of activity that were uniquely associated with note identity. Hence, units of vocal be havior are represented hierarchically in the avian forebrain. The repr esentation of temporal sequences at each level of the hierarchy may be established by means of a decoding process involving Interactions of higher level input with intrinsic local circuitry. Behavior is apparen tly represented by precise temporal patterning of spike trains at lowe r levels of the hierarchy.