Semilunar Granule Cells: Glutamatergic Neurons in the Rat Dentate Gyrus with Axon Collaterals in the Inner Molecular Layer

• DOI: 10.1523/jneurosci.4053-07.2007
• Publication Date: 2007-12-12T17:28:38Z
• Authors: Philip A. Williams; Phillip Larimer; Yuan Gao; Ben W. Strowbridge
• Keywords: Granule cell; Granular layer; Fascia dentata

Synaptic reorganization of the dentate gyrus inner molecular layer (IML) is a pathophysiological process that may facilitate seizures in patients with temporal-lobe epilepsy. Two subtypes IML neurons were originally described by Ramón y Cajal (1995), but have not been thoroughly studied. We used two-photon imaging, infrared-differential interference contrast microscopy and patch clamp recordings from rat hippocampal slices to define intrinsic physiology synaptic targets spiny, granule-like IML, termed semilunar granule cells (SGCs). These resembled had axon collaterals layer, significantly larger dendritic arborization more triangular cell body than cells. Unlike cells, SGCs fired throughout long-duration depolarizing steps ramp-like depolarizations during interspike periods. Paired demonstrated are glutamatergic monosynaptically excite both hilar interneurons mossy Semilunar appear represent distinct excitatory neuron population be an important target for fiber sprouting rodent models temporal lobe