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Abstract #1195

Complexity in the Spatiotemporal Hemodynamic Response to Sensory Stimulation in the Un-Anesthetized Rat

Christopher James Martin1, Jason Berwick2, Ying Zheng2, John Mayhew2

1Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom; 2University of Sheffield

The aim of this work was to investigate the spatiotemporal changes in hemodynamics that underlie fMRI signal changes in response to stimulus evoked changes in neuronal activity. We used optical imaging spectroscopy in an un-anesthetized rat model, to provide measures of changes in blood volume and oxygenation at higher spatial and temporal resolution than possible with fMRI, without the potentially confounding effects of anesthesia. We found a complex spatiotemporal hemodynamic response function, consisting of both increases and decreases in blood volume and oxygenation as well as oscillatory response components. We discuss the implications of these findings for fMRI.