Investigation of Linear Coupling Between Single-Event Blood Flow Responses and Interictal Discharges in a Model of Experimental Epilepsy

A successful outcome of epilepsy neurosurgery relies on an accurate delineation of the epileptogenic region to be resected. Functional magnetic resonance imaging (fMRI) would allow doing this noninvasively at high spatial resolution. However, a clear, quantitative description of the relationship between hemodynamic changes and the underlying epileptiform neuronal activity is still missing, thereby preventing the systematic use of fMRI for routine epilepsy surgery planning. To this aim, we used a local epilepsy model to record simultaneously cerebral blood flow (CBF) with laser Doppler (LD) and local field potentials (LFP) in rat frontal cortex. CBF responses to individual interictal-like spikes were large and robust. Their amplitude correlated linearly with spike amplitude. Moreover, the CBF response added linearly in time over a large range of spiking rates. CBF responses could thus be predicted by a linear model of the kind currently used for the interpretation of fMRI data, but including also the spike...