How sleep affects the developmental learning of bird song

Sleep affects learning and development in humans and other animals, but the role of sleep in developmental learning has never been examined. Here we show the effects of night-sleep on song development in the zebra finch by recording and analysing the entire song ontogeny. During periods of rapid learning we observed a pronounced deterioration in song structure after night-sleep. The song regained structure after intense morning singing. Daily improvement in similarity to the tutored song occurred during the late phase of this morning recovery; little further improvement occurred thereafter. Furthermore, birds that showed stronger post-sleep deterioration during development achieved a better final imitation. The effect diminished with age. Our experiments showed that these oscillations were not a result of sleep inertia or lack of practice, indicating the possible involvement of an active process, perhaps neural song-replay during sleep. We suggest that these oscillations correspond to competing demands of plasticity and consolidation during learning, creating repeated opportunities to reshape previously learned motor skills. Chorus line: sleep as a learning aid Here's a project that needed more than a few iPods for sound storage. Derégnaucourt et al . studied the entire vocal development in a songbird, analysing over a million song syllables per bird. Like humans learning to speak, songbirds have a sensitive period (30–90 days after hatching in the zebra finch) when they are extremely effective at vocal learning. The experiment involved continuously recording every song sung by a group of zebra finches, and revealed a strong oscillatory effect of sleep on song learning in young birds. Song performance deteriorates in the morning, and recovers after intensive morning singing. The oscillations seem significant, as birds showing strong daily oscillations achieved a better final imitation. The birds may be replaying songs during sleep, gaining repeated opportunities to reshape previously learned skills.