Abstract
Dravet syndrome (DS) is a neurodevelopmental disorder defined by treatment-resistant epilepsy, autism spectrum disorder, and sudden death, due to pathogenic variants in SCN1A encoding the Nav1.1 sodium channel subunit. Convergent data suggest hippocampal dentate gyrus (DG) pathology. We found that optogenetic stimulation of entorhinal cortex was ictogenic in DS (Scn1a+/-) but not wild-type mice in vivo. Two-photon calcium imaging in brain slice demonstrated profound impairment in filtering of perforant path input by DG in young adult Scn1a+/- mice due to enhanced excitatory input to granule cells. Excitability of parvalbumin interneurons (PV-INs) was near-normal and selective activation of PV-INs rescued circuit impairments. This demonstrates developmental reorganization of hippocampal circuitry that can be modulated by recruitment of functional PV-INs, suggesting potential therapeutic approaches towards seizure modulation. The identified circuit abnormality mirrors that seen in models of chronic temporal lobe epilepsy, suggesting convergent mechanisms linking genetic and acquired causes of temporal lobe-onset seizures.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
J.M. and E.M.G. designed the experimental study. J.M. conducted all imaging experiments. A.S. performed analysis of the imaging data. J.M., K.M.G., L.M.M., and K.K. conducted the slice physiology experiments. J.M. and K.M.G. performed analysis of the slice physiology data. J.M., N.S., and H.F. conducted the in vivo experiments. J.Y. assisted with animal husbandry and viral injections. J.M. and E.M.G. wrote the manuscript.
