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Optogenetic Activation of Afferent Pathways in Brain Slices and Modulation of Responses by Volatile Anesthetics
Published on: July 23, 2020
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Bird-like propagating brain activity in anesthetized Nile crocodiles
Ryan K Tisdale1, John A Lesku2, Gabriel J L Beckers3
1Avian Sleep Group, Max Planck Institute for Ornithology, Seewiesen, Germany.
Sleep
|June 30, 2018
Summary
High-voltage sharp waves (HShW) in crocodiles exhibit complex propagation patterns similar to avian slow waves. This suggests HShW may represent an ancestral form of slow-wave sleep (SWS) found in mammals and birds.
Area of Science:
- Neuroscience
- Comparative Physiology
- Sleep Research
Background:
- Mammalian and avian sleep feature electroencephalogram (EEG) slow waves during slow-wave sleep (SWS).
- Non-avian reptiles exhibit high-voltage sharp waves (HShW) during sleep, with their relation to SWS unclear.
- The dorsal ventricular ridge (DVR) is implicated in HShW generation.
Purpose of the Study:
- To investigate the spatiotemporal patterns of electrophysiological phenomena in Nile crocodiles.
- To determine if HShW in crocodiles share similarities with mammalian and avian slow waves.
- To explore the evolutionary origins of SWS.
Main Methods:
- Electrophysiological recordings using 64-channel penetrating arrays in anesthetized Nile crocodiles.
- Electrodes were arranged in an 8x8 grid and placed in the dorsal ventricular ridge (DVR).
- Analysis of spatiotemporal distribution of recorded signals.
Main Results:
- High-voltage sharp waves (HShW) were detected, consistent with previous reptile sleep studies.
- HShW demonstrated complex and variable propagation patterns across the DVR.
- Observed HShW propagation patterns resemble those of avian slow waves in homologous brain regions.
Conclusions:
- HShW propagation in crocodiles shares spatiotemporal similarities with avian slow waves.
- Sleep characterized by HShW may represent an ancestral form of SWS.
- This ancestral SWS form likely had less frequent and shorter up-states compared to mammals and birds.
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