Investigating the neurophysiological control of sleep in birds

• Applicant: Janie Ondracek, Ph.D.
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 580142783

Sleep can be described as a set of behavioral and physiological markers that include behavioral quiescence, reduced muscle tone, changes in hormone and temperature regulation, and the switching between sleep-related brain states. The major features of sleep were first defined in mammals. Interestingly, of the non-mammalian vertebrates studied so far, birds share a large number of sleep features with mammals, including eye closure, sleep-specific postures, and similar electrophysiological signatures of sleep. Avian sleep is comparable to mammalian sleep due to the largely uncontested presence of both slow wave sleep (SWS) and rapid eye movement sleep (REM). Although decades of research have revealed numerous brain regions that are involved in the control and regulation of sleep, two brain areas have been extensively characterized as important hubs of wake-sleep regulation in mammals: the locus coeruleus (LC) and the ventrolateral preoptic area (VLPO). Although the LC has long been associated with the ascending arousal system its role in sleep and wakefulness has recently been shown to be far more complex than originally thought. Similarly, the VLPO has been recognized as critically important in sleep regulation through the activity of its inhibitory neuron populations. Despite both areas being essential for the regulation of sleep and wakefulness in mammals, almost nothing is known about the activity of these brain areas in birds. In this project, we aim to investigate the activity of the avian LC and VLPO to identify whether these brain areas are involved in the theoretical "flip-flop" model of behavioral state transitions between wake and sleep. In Aim 1, we will characterize the anatomy and electrophysiological properties of neurons in the avian LC and VLPO with whole cell patch recordings in chicken brain slices. Characterization of neural responses from these brain areas do not yet exist in birds; our results will be the first examination of the response properties, pharmacological underpinnings, and anatomy of neurons in the LC and VLPO in birds. In Aim 2, we will use EEG electrodes to record and characterize natural sleep and sleep-state switching in juvenile chickens. Using a combination of electrophysiology and behavior data streams, we will develop an algorithm to track sleep state switching in chickens in real-time. In Aim 3 we will relate LC and VLPO activity to the ongoing sleep EEG using a combination of in vivo electrophysiology, neural silencing, and reversible delivery of pharmacological agents to the LC and VLPO. As nothing is known about the neural activity of the avian LC and VLPO during sleep, the results of these experiments will provide completely novel information that will help to identify the function of the avian LC and VLPO and will help shed light on the evolution of the "flip-flop" switch across vertebrates.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Harald Luksch