Uncoupled Couplings: Combined Fmri and 1h-mrs for the Study of the Neurovascular and Neurometabolic Coupling

Purpose Functional magnetic resonance imaging (fMRI) is the tool of choice for mapping brain function. Unfortunately, the blood oxygenation level dependent (BOLD) contrast is essentially a vascular effect and hence only an indirect measure of neural activity. Accordingly, BOLD is found to reflect synaptic, more than spiking, activity and it is potentially independent on energy requirements [1]. As such, the exact relationship between BOLD fMRI signal and neural processes (action potentials and inhibitory/excitatory postsynaptic potentials) is still elusive. Here we combined fMRI with proton magnetic resonance spectroscopy (1H-MRS) to study the vascular and metabolic response of the brain by activating different pathways within the central visual system. The aim of the present study is to examine the neural events underlying functional brain images and the metabolism of the activated tissue.