Spatial, contextual and working memory are not affected by the absence of mossy fiber long-term potentiation and depression.
The mossy fibers of the hippocampus display NMDA-receptor independent long-term plasticity. A number of studies addressed the role of mossy fiber long-term plasticity in memory, but have provided contrasting results. Here, we have exploited a genetic model, the rab3A null-mutant, which is characterized by the absence of both mossy fiber long-term potentiation and long-term depression. This mutant was backcrossed to 129S3/SvImJ and C57Bl/6J to obtain standardized genetic backgrounds. Spatial working memory, assessed in the eight-arm radial maze, was unchanged in rab3A null-mutants. Moreover, one-trial cued and contextual fear conditioning was normal. Long-term spatial memory was tested in the Morris water maze. Two different versions of this task were used, an 'easy' version and a 'difficult' one. On both versions, no differences in search time and quadrant preferences were observed. Thus, despite the elimination of mossy fiber long-term plasticity, these tests revealed no impairments in mnemonic capabilities. We conclude that spatial, contextual and working memory do not depend on mossy fiber plasticity.
Hensbroek
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RA
Rudolf Magnus Institute for Neurosciences, Utrecht University Medical Center, Universiteitsweg 100, 3584CG Utrecht, The Netherlands.
Kamal
A
A
Baars
A M
AM
Verhage
M
M
Spruijt
B M
BM
D000818:Animals; D001245:Association Learning / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology; D003433:Crosses, Genetic; D004924:Escape Reaction / Q000502:physiology; D005239:Fear / Q000502:physiology; D005260:Female; D006580:Genetic Carrier Screening; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D008818:Mice, Neurologic Mutants; D019599:Mossy Fibers, Hippocampal / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D012153:Retention, Psychology / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate