Dravet Syndrome is a rare epileptic disorder, which is caused in more than 70% of all patients by a loss-of-function mutation in the SCN1A gene encoding sodium channel Nav1.1. One of the main problems for treatment of patients with Dravet Syndrome is drug resistance and there are no biomarkers to monitor the efficacy of a particular treatment. The Dravet Syndrome phenotype can be recapitulated in mice by knockout of the Scn1a gene. Previous studies revealed a reduced sodium current in inhibitory GABAergic interneurons in a mouse model of Dravet Syndrome which leads to reduced excitability of inhibitory GABAergic inter-neurons. Inhibition of inhibitory GABAergic interneurons can lead to decreased phase-amplitude coupling between theta (5-10 Hz) and gamma (50-70 Hz) or theta and high gamma (100-140 Hz) oscillations in the brain. To investigate whether impaired phase-amplitude coupling could be a potential biomarker to monitor the efficacy of treatment for Dravet Syndrome, we recorded electrocorticogram signals from the primary visual cortex in two mice models of Dravet Syndrome and wild type mice. We found a decrease in theta-high gamma coupling for mice with Dravet Syndrome in the early epileptic stage and a decrease in theta-gamma and theta-high gamma coupling in mice with Dravet Syndrome in which seizure onset had already started, during rapid-eye-movement sleep. Reduced excitability of inhibitory GABAergic interneurons can also cause hyper-excitability that leads to seizures. These results suggest that phase amplitude coupling could be a potential biomarker to monitor the efficacy of treatment for Dravet Syndrome. Efficient treatment decreases the number of seizures and therefore we expect to see an increase in theta-gamma and theta-high gamma coupling.