Ultrafast fMREye scanning of oculo-cerebral pulsations
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
Auditorium 7 (Kajaanintie 50, N entrance), Oulu University Hospital
Topic of the dissertation
Ultrafast fMREye scanning of oculo-cerebral pulsations
Doctoral candidate
Master of Medical Physics Seyed Mohsen Ebrahimi
Faculty and unit
University of Oulu Graduate School, Faculty of Medicine, Research Unit of Health Sciences and Technology
Subject of study
Medical Physics and Technology
Opponent
Professor Koen Van Leemput, Aalto University
Custos
Professor Vesa Kiviniemi, University of Oulu
How Do the Eye and Brain Pulse Together?
The eye and brain are constantly affected by physiological pulsations generated by the heartbeat, breathing, and slow changes in blood vessels. These pulsations may help move fluids and dissolved substances through tissues and may therefore contribute to the removal of metabolic waste.
In this doctoral research, an ultrafast magnetic resonance imaging method called fMREye was developed to measure physiological pulsations in the human eye and compare them with pulsations in the brain. The studies showed that the eye contains clear pulsations related to breathing, the heartbeat, and slow vascular activity. Respiratory pulsations were particularly prominent in the eye.
The research also examined whether the autonomic nervous system affects these pulsations. Tropicamide eye drops, which reduce parasympathetic activity in the eye, decreased pulsation power in several ocular structures and also produced changes around the eye and in the brain.
Finally, the study investigated how eye and brain pulsations interact over time. The results showed that their relationship is dynamic and bidirectional. Neither the brain nor the eye acts as a permanent driver; instead, the direction of interaction changes over time and differs between physiological frequency bands.
These findings provide new non-invasive information about the physiological connection between the eye and brain. The methods developed in this thesis may support future research into altered fluid dynamics in conditions such as glaucoma and neurological diseases.
In this doctoral research, an ultrafast magnetic resonance imaging method called fMREye was developed to measure physiological pulsations in the human eye and compare them with pulsations in the brain. The studies showed that the eye contains clear pulsations related to breathing, the heartbeat, and slow vascular activity. Respiratory pulsations were particularly prominent in the eye.
The research also examined whether the autonomic nervous system affects these pulsations. Tropicamide eye drops, which reduce parasympathetic activity in the eye, decreased pulsation power in several ocular structures and also produced changes around the eye and in the brain.
Finally, the study investigated how eye and brain pulsations interact over time. The results showed that their relationship is dynamic and bidirectional. Neither the brain nor the eye acts as a permanent driver; instead, the direction of interaction changes over time and differs between physiological frequency bands.
These findings provide new non-invasive information about the physiological connection between the eye and brain. The methods developed in this thesis may support future research into altered fluid dynamics in conditions such as glaucoma and neurological diseases.
Created 23.9.2026 | Updated 23.9.2026