Rapid Iris Movements in Birds: a New Window into the Awake and Sleeping Avian Brain

• Applicant: Dr. Gianina Ungurean
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 557940889

The pupils of the eyes are more than just protective, mechanical, camera-like apertures that open in dim and close in bright light. In humans and other mammals, the pupils also respond to internal changes in the brain, such as shifts in attention, arousal, emotion, and cognition. Consequently, the pupil is considered a window into the brain. Other vertebrates, like birds, reptiles, and fish, also possess pupils, but do they provide the same view into the brain? Surprisingly, in a recent study which I led during my PhD, we discovered that avian pupils behave opposite those of mammals during wakefulness and sleep, raising the possibility that the pupils of birds provide a different and unexplored window into animal minds. I aim to explore this question through the proposed project. During the last part of my PhD, together with collaborators, I established a paradigm for imaging the brain of head-fixed sleeping birds. As a postdoc, I learned and mastered a new whole-brain imaging method - functional ultrasound imaging - on mice, and successfully implemented on birds in a pilot experiment. In the proposed project, I aim to expand these experiments and to combine my skills in whole brain imaging, electrophysiology and behavior, to investigate the functions and the neural mechanisms underlying pupil behavior in awake and sleeping birds. Specifically, I aim to: 1) identify the brain areas involved in changes in pupil size during wake and sleep in birds; 2) investigate whether avian pupil activity during sleep is like other muscle twitches, or whether it marks moments when the brain replays daily events; 3) study whether awake pupil activity plays a role in social communication in birds.

• DFG Programme: Research Grants