Somatostatin-positive interneurons in the dentate gyrus of mice provide local- and long-range septal synaptic inhibition

• Published in: eLife
• Main Authors: Mei Yuan, Thomas Meyer, Christoph Benkowitz, Shakuntala Savanthrapadian, Laura Ansel-Bollepalli, Angelica Foggetti, Peer Wulff, Pepe Alcami, Claudio Elgueta, Marlene Bartos
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2017-04-01
• Subjects: somatostatin; dentate gyrus; synaptic transmission; medial septum; interneuron; synaptic plasticity
• Online Access: https://elifesciences.org/articles/21105

Somatostatin-expressing-interneurons (SOMIs) in the dentate gyrus (DG) control formation of granule cell (GC) assemblies during memory acquisition. Hilar-perforant-path-associated interneurons (HIPP cells) have been considered to be synonymous for DG-SOMIs. Deviating from this assumption, we show two functionally contrasting DG-SOMI-types. The classical feedback-inhibitory HIPPs distribute axon fibers in the molecular layer. They are engaged by converging GC-inputs and provide dendritic inhibition to the DG circuitry. In contrast, SOMIs with axon in the hilus, termed hilar interneurons (HILs), provide perisomatic inhibition onto GABAergic cells in the DG and project to the medial septum. Repetitive activation of glutamatergic inputs onto HIPP cells induces long-lasting-depression (LTD) of synaptic transmission but long-term-potentiation (LTP) of synaptic signals in HIL cells. Thus, LTD in HIPPs may assist flow of spatial information from the entorhinal cortex to the DG, whereas LTP in HILs may facilitate the temporal coordination of GCs with activity patterns governed by the medial septum.