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Authors & Affiliations
Juliane Böge, Christina Strauch, Olena Shchyglo, Valentyna Dubovyk, Denise Manahan-Vaughan
Abstract
The dentate gyrus (DG) serves as an information gateway to the hippocampal formation. It receives sensory information from entorhinal cortex via perforant path (PP) and can be subdivided into parts including a supra- and an infrapyramidal blade. Typically, synaptic plasticity within the DG has mostly been examined in the suprapyramidal blade, whereas little is known about the extent to which synaptic plasticity is expressed and maintained in the infrapyramidal blade.This study compared synaptic plasticity in both blades of the DG that was evoked by patterned electrophysiological stimulation of the PP of freely behaving rats. To compare membrane and action potential properties in granule cells of both blades, patch clamp recordings were performed in hippocampal slices. In addition, N-methyl-D-aspartate receptor (NMDAR) subunit expression was assessed using immunohistochemistry.Long-term potentiation (LTP, >24h) was induced in the suprapyramidal blade using patterned PP stimulation at 200Hz, whereas a higher afferent frequency was needed to induce LTP in the infrapyramidal blade. Long-term depression was weaker in the infrapyramidal compared to the suprapyramidal blade. Patch clamp recordings revealed differences in specific action potential properties, whereas passive membrane properties were similar in both blades. In the infrapyramidal blade, NMDAR subunit expression was significantly lower than in the suprapyramidal blade.These results suggest each DG blade can be differentiated on the basis of the frequency-dependency of synaptic plasticity, the NMDAR receptor content and cellular properties, pointing to distinct roles of these structures in hippocampal information processing and storage. Supported by the Deutsche Forschungsgemeinschaft (SFB1280/A04, project number: 316803389).