Epilepsy is a prevalent neurological disorder affecting more than 1 % of all people, with the estimated number of 900,000 children and adolescents suffering from active epilepsy in Europe. Most current drugs targeting this disease have important adverse side-effects. An ideal drug would, however, potentiate the endogenous anti-seizure mechanisms that keep most humans epilepsy-free.To date, these native “anti-seizure mechanisms” have not been identified. Recently, a novel candidate mechanism termed “supply-rate depression” was functionally characterized. It is only induced by excessive synaptic use, after which it dampens all pre-synaptic function for several minutes.This proposal would test whether lowering the threshold for inducing supply-rate depression is protective against epilepsy using genetically engineered mice, and will additionally test a structure/function hypothesis related to the assembly of the vesicles in presynaptic terminal that could lead to a high-throughput drug screen.These goals will be accomplished via the following Specific Aims:1. To generate a synapsin 2 conditional knockout mouse line where synapsin 2 is deleted exclusively at excitatory synapses and thereby speed the onset of the protective mechanism at excitatory synapses.2. To evaluate the susceptibility to seizures of the synapsin 2 conditional knockout mice using chemically induced models of epilepsy.3. To apply state-of-the-art electron microscopy tomography techniques to test the structure/function hypothesis that the lengths of presynaptic vesicle tethering units are ~ 40% shorter in presynaptic terminals of synapsin 2 knockout synapses.Results of this project may justify a large-scale industrial effort for developing a new generation of anti-epileptic drugs that target supply-rate depression. Thus, these new substances should have reduced occurrence and magnitude of unwanted side effects and would immensely improve the well-being of affected people.