Published in:
Open Access
01-12-2014 | Research
Enhanced stability of hippocampal place representation caused by reduced magnesium block of NMDA receptors in the dentate gyrus
Authors:
Yuichiro Hayashi, Yoko Nabeshima, Katsunori Kobayashi, Tsuyoshi Miyakawa, Koichi Tanda, Keizo Takao, Hidenori Suzuki, Eisaku Esumi, Shigeru Noguchi, Yukiko Matsuda, Toshikuni Sasaoka, Tetsuo Noda, Jun-ichi Miyazaki, Masayoshi Mishina, Kazuo Funabiki, Yo-ichi Nabeshima
Published in:
Molecular Brain
|
Issue 1/2014
Login to get access
Abstract
Background
Voltage-dependent block of the NMDA receptor by Mg2+ is thought to be central to the unique involvement of this receptor in higher brain functions. However, the in vivo role of the Mg2+ block in the mammalian brain has not yet been investigated, because brain-wide loss of the Mg2+ block causes perinatal lethality. In this study, we used a brain-region specific knock-in mouse expressing an NMDA receptor that is defective for the Mg2+ block in order to test its role in neural information processing.
Results
We devised a method to induce a single amino acid substitution (N595Q) in the GluN2A subunit of the NMDA receptor, specifically in the hippocampal dentate gyrus in mice. This mutation reduced the Mg2+ block at the medial perforant path–granule cell synapse and facilitated synaptic potentiation induced by high-frequency stimulation. The mutants had more stable hippocampal place fields in the CA1 than the controls did, and place representation showed lower sensitivity to visual differences. In addition, behavioral tests revealed that the mutants had a spatial working memory deficit.
Conclusions
These results suggest that the Mg2+ block in the dentate gyrus regulates hippocampal spatial information processing by attenuating activity-dependent synaptic potentiation in the dentate gyrus.