Distinct periods of cannabinoid sensitivity during zebra finch vocal development.

Zebra finch song is a form of vocal communication learned during at least two distinct stages of late postnatal development. During the first of these stages, termed auditory learning, nestlings memorize the song pattern of an adult male tutor, usually the father. During the second stage, sensory-motor learning, these song patterns are practiced and refined until a good copy is produced by adulthood. Vocal learning has made zebra finches a useful model for studying drug effects during vocal development. Prior work has shown that daily exposure to a modest dosage of the cannabinoid agonist WIN55212-2 (WIN) alters sensory-motor learning by reducing stereotypy scores and numbers of note types learned. Here we report that these two effects are produced independently during subperiods of the sensory-motor learning stage. Additional temporally distinct WIN effects during sensory-motor learning include differential incorporation of tutor-derived and improvised note types. We have also evaluated acute and chronic effects of WIN exposure on ability to encode a tutor's song during auditory learning, finding significant effects on stereotypy and distinct effects on note duration and internote intervals. Taken together, these results demonstrate the presence of distinct subperiods of cannabinoid sensitivity during zebra finch auditory and sensory-motor vocal development.