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Session: Neurological disorders
Session starts: Thursday 24 January, 13:30
Presentation starts: 13:45
Room: Lecture room 536

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Herke Jan Noordmans (University Medical Center Utrecht)
Dorien van Blooijs ()
Jeroen Siero ()
Jaco Zwanenburg ()
John Klaessens ()
Nick Ramsey ()

Abstract:
Introduction Slow sinusoidal, hemodynamic oscillations (SSHOs) around 0.1 Hz are frequently seen in mammalian and human brains. Four patients undergoing functional surgery for epilepsy offered a unique opportunity to determine which SSHOs are present on the human brain. Methods Hyper-spectral recordings of 4 to 7 wavelengths were made with a two systems: 1) consisting of liquid crystal tunable filter and a monochrome camera mounted to the surgical microscope, 2) consisting of a flat panel light source with 600 LEDs with 17 peak-wavelengths with a monochrome camera mounted in the middle. Concentrations of oxy- and deoxy-hemoglobin were calculated for each set of wavelengths and image pixel. A Fourier transform was applied along the time axis to determine the oscillating amplitude at each frequency. Oscillating regions were determined by manually delineating bright areas. Results For all 4 patients multiple SSHOs were constantly visible during the entire 4 to 10 minute acquisition time. The observed SSHOs were localized to specific cortical regions with a very distinct frequencies and showed a fixed but sometimes large phase difference within that region. SSHOs of deoxygenated hemoglobin appeared to have an opposite phase with respect to the oxygenated hemoglobin SSHOs. Deoxyhemoglobin SSHOs’ amplitude was 90% of the oxygenated hemoglobin SSHOs’ amplitude. Discussion & Conclusion Despite the fact that SSHOs have been known for many decades, their function is still unknown. This study shows that SSHOs have very specific characteristics like frequency, phase and location. More research is needed to study their dependence on pathology, anesthetics and electrical or visual stimuli. Hyper-spectral imaging of the human brain offers a new way to study the origin and function of SSHOs on the human brain.