Research
Hippocampal function is not required for the precision of remote place memory
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* Corresponding author: Kaoru Inokuchi inokuchi@med.u-toyama.ac.jp
1 Department of Biochemistry, Faculty of Medicine, Graduate School of Medicine & Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
2 Japan Science and Technology Agency, CREST, Kawaguchi 332-0012, Japan
3 Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo 194-8511, Japan
4 Division of Animal Experimental Laboratory, Life Science Research Center, University of Toyama, Toyama 930-0194, Japan
5 Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo 156-8502, Japan
6 Present address: RIKEN-MIT Center for Neural Circuit Genetics and the Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, 02139, USA
Molecular Brain 2012, 5:5 doi:10.1186/1756-6606-5-5
Published: 2 February 2012Abstract
Background
During permanent memory formation, recall of acquired place memories initially depends on the hippocampus and eventually become hippocampus-independent with time. It has been suggested that the quality of original place memories also transforms from a precise form to a less precise form with similar time course. The question arises of whether the quality of original place memories is determined by brain regions on which the memory depends.
Results
To directly test this idea, we introduced a new procedure: a non-associative place recognition memory test in mice. Combined with genetic and pharmacological approaches, our analyses revealed that place memory is precisely maintained for 28 days, although the recall of place memory shifts from hippocampus-dependent to hippocampus-independent with time. Moreover, the inactivation of the hippocampal function does not inhibit the precision of remote place memory.
Conclusion
These results indicate that the quality of place memories is not determined by brain regions on which the memory depends.