Related Experiment Video
Updated: Feb 8, 2026

Optogenetic Activation of Afferent Pathways in Brain Slices and Modulation of Responses by Volatile Anesthetics
Published on: July 23, 2020
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.
Study Objectives:
The changes in electroencephalogram (EEG) activity that characterize sleep and its sub-states-slow-wave sleep (SWS) and rapid eye movement (REM) sleep-are similar in mammals and birds. SWS is characterized by EEG slow waves resulting from the synchronous alternation of neuronal membrane potentials between hyperpolarized down-states with neuronal quiescence and depolarized up-states associated with action potentials. By contrast, studies of non-avian reptiles report the presence of high-voltage sharp waves (HShW) during sleep. How HShW relate to EEG phenomena occurring during mammalian and avian sleep is unclear. We investigated the spatiotemporal patterns of electrophysiological phenomena in Nile crocodiles (Crocodylus niloticus) anesthetized with isoflurane to determine whether they share similar spatiotemporal patterns to mammalian and avian slow waves.
Methods:
Recordings of anesthetized crocodiles were made using 64-channel penetrating arrays with electrodes arranged in an 8 × 8 equally spaced grid. The arrays were placed in the dorsal ventricular ridge (DVR), a region implicated in the genesis of HShW. Various aspects of the spatiotemporal distribution of recorded signals were investigated.
Results:
Recorded signals revealed the presence of HShW resembling those reported in earlier studies of naturally sleeping reptiles. HShW propagated in complex and variable patterns across the DVR.
Conclusions:
We demonstrate that HShW within the DVR propagate in complex patterns similar to those observed for avian slow waves recorded from homologous brain regions. Consequently, sleep with HShW may represent an ancestral form of SWS, characterized by up-states occurring less often and for a shorter duration than in mammals and birds.
More Related Videos
14:52Recording Brain Electromagnetic Activity During the Administration of the Gaseous Anesthetic Agents Xenon and Nitrous Oxide in Healthy Volunteers
Published on: January 13, 2018
09:48Neural Activity Propagation in an Unfolded Hippocampal Preparation with a Penetrating Micro-electrode Array
Published on: March 27, 2015
Related Concept Videos
Local Anesthetics: Chemistry and Structure-Activity Relationship
Propagation of Waves
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
Propagation of Action Potentials
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
Local Anesthetics: Pharmacokinetics
Inhalational Anesthetics: Overview
Parenteral Anesthetics: Overview