MRI/DOI NEURONAVIGATION: REVISITING THE NEGATIVE BOLD SIGNAL THROUGH DIFFUSE OPTICAL IMAGING

In this work the use of a neuronavigation system enables to couple diffuse optical imaging (DOI) and magnetic resonance imaging (MRI) modalities, outside the MRI magnet in real-time. When used with the optical probes, it enables monitoring of the position of the fibers with respect to the anatomy and provides an image of the sensitivity matrix on the anatomical substrate. Given this structural information, we can determine and localize almost exactly the region we want to probe and then position the optical sensors at the right place on the subject´s head. We apply these techniques to the measurement of activation during a finger tapping task, in particular the negative BOLD signal observed in fMRI is revisited within the optical framework.