@article{Architecture:2068,
      recid = {2068},
      author = {Canavan, Sophia Victoria},
      title = {Avian Sleep Architecture and Motor Replay},
      publisher = {The University of Chicago},
      school = {Ph.D.},
      address = {2019-12},
      pages = {274},
      abstract = {Birds, like mammals, have multiple forms of sleep  including rapid eye movement sleep (REM) and slow wave  sleep (SWS). It is not known why or how these specialized  stages of sleep evolved. For many decades, the overwhelming  consensus was that avian sleep was more primitive. This led  to the conclusion that complex sleep evolved independently  in mammals and birds.

Recently, songbirds were found to  have surprisingly mammalian-like sleep architecture as well  as sleep replay of song, a learned motor skill. In mammals,  sleep replay in hippocampal place cells is thought to be a  central mechanism for the function of sleep in learning and  memory. The well-established co-occurrence of hippocampal  replay with slow waves demonstrates the link between global  sleep architecture and circuit-level mediators of sleep  function. However, sleep has profound effects not only on  hippocampal-dependent declarative memory, but also on  procedural memory. Song replay, as the only other confirmed  exemplar of sleep replay, thus offers a chance to study a  similar mechanism within a procedural memory system. I  sought to better understand how sleep architecture is  expressed across multiple bird species, and how song replay  is related to sleep structure.

I characterized sleep  architecture in budgerigars (Melopsittacus undulatus),  finding multiple signs of complex, highly structured, and  mammalian-like sleep. These traits included patterns of REM  increase and SWS decrease, a stage of intermediate sleep  that remained consistent over the night, a 34-minute sleep  cycle, and the largest amount of REM found in adults of any  bird species to date (26.5%). Furthermore, I demonstrated  that a major source of error in earlier studies was the use  of constant light, which I found to abolish the circadian  rhythm, decrease total sleep, and fragment sleep  episodes.

Using automated techniques, I went on to confirm  recent results on sleep architecture in zebra finches  (Taeniopygia guttata) and characterized the sleep/wake  cycle over 24 hours. The findings are consistent with  mammalian-like patterns of REM increase and SWS decrease,  contradicting older reports of songbird sleep. I also  observed a 38-minute sleep cycle in zebra finches. These  results indicate that complex sleep structure is most  likely to includes the majority of extant species of birds  (songbirds and parrots), and promotes re-evaluation of the  evolutionary history of complex sleep in birds and in  mammals.

As part of the work on sleep replay, I was  involved in an effort to develop techniques for chronic  multielectrode array recordings in zebra finches. These  methods are described here in detail to facilitate  replication of this technique, including implant  construction, surgery, recording, and spikesorting. I used  this technique to record from the nucleus robustus of the  arcopallium (RA), the motor cortex analogue of the song  system. By combining chronic recordings of RA activity with  polysomnography over multiple sleep/wake cycles, I was able  to examine the relationship between song replay and sleep  structure. Song replay was most strongly linked to non-REM,  occurred during periods of higher slow wave activity, and  often co-occurred with local slow waves. Replay events most  often occurred at or near real-time, in contrast with the  highly compressed replay of the hippocampus. These results  establish for the first time similarities and differences  in sleep replay comparing declarative and procedural  memories.

In sum these results show that highly complex  sleep traits manifest across songbirds and parrots, and  that complex sleep architecture is linked to song replay.  This supports the hypothesis that shared attributes of  avian and mammalian sleep are derived from a common  precursor, and helps to illuminate underlying mechanisms by  which complex sleep can affect procedural memory.},
      url = {http://knowledge.uchicago.edu/record/2068},
      doi = {https://doi.org/10.6082/uchicago.2068},
}