title: Time-place learning and memory persist in mice lacking functional Per1 and Per2 clock genes.
abstract: With time-place learning, animals link a stimulus with the location and the time of day. This ability may optimize resource localization and predator avoidance in daily changing environments. Time-place learning is a suitable task to study the interaction of the circadian system and memory. Previously, we showed that time-place learning in mice depends on the circadian system and Cry1 and/or Cry2 clock genes. We questioned whether time-place learning is Cry specific or also depends on other core molecular clock genes. Here, we show that Per1/Per2 double mutant mice, despite their arrhythmic phenotype, acquire time-place learning similar to wild-type mice. As well as an established role in circadian rhythms, Per genes have also been implicated in the formation and storage of memory. We found no deficiencies in short-term spatial working memory in Per mutant mice compared to wild-type mice. Moreover, both Per mutant and wild-type mice showed similar long-term memory for contextual features of a paradigm (a mild foot shock), measured in trained mice after a 2-month nontesting interval. In contrast, time-place associations were lost in both wild-type and mutant mice after these 2 months, suggesting a lack of maintained long-term memory storage for this type of information. Taken together, Cry-dependent time-place learning does not require Per genes, and Per mutant mice showed no PER-specific short-term or long-term memory deficiencies. These results limit the functional role of Per clock genes in the circadian regulation of time-place learning and memory.
authors: Department of Molecular Neurobiology.
authors: C
authors: C
authors: Mulder
authors: E A
authors: EA
authors: Van Der Zee
authors: R A
authors: RA
authors: Hut
authors: M P
authors: MP
authors: Gerkema
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D056931:Cryptochromes / Q000235:genetics / Q000502:physiology; D005838:Genotype; D007858:Learning / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology*; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D056950:Period Circadian Proteins / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D013997:Time Factors
chemical_list: C538964:Cry1 protein, mouse; C538967:Cry2 protein, mouse; D056931:Cryptochromes; C539023:Per1 protein, mouse; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins
keywords: Cryptochrome; Period; circadian; memory; mice; time-place learning