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Role of Aging and Hippocampus in Time-Place Learning: Link to Episodic-Like Memory?
- Source :
- Frontiers in Behavioral Neuroscience, Frontiers in Behavioral Neuroscience, 9:362. Frontiers Media S.A., Frontiers in Behavioral Neuroscience, Vol 9 (2016)
- Publication Year :
- 2016
- Publisher :
- Frontiers Media S.A., 2016.
-
Abstract
- Introduction: With time-place learning (TPL), animals link an event with the spatial location and the time of day (TOD). The what-where-when TPL components make the task putatively episodic-like in nature. Animals use an internal sense of time to master TPL, which is circadian system based. Finding indications for a role of the hippocampus and (early) aging-sensitivity in TPL would strengthen the episodic-like memory nature of the paradigm.Methods: Previously, we used C57Bl/6 mice for our TPL research. Here, we used CD1 mice which are less hippocampal-driven and age faster compared to C57Bl/6 mice. To demonstrate the low degree of hippocampal-driven performance in CD1 mice, a cross maze was used. The spontaneous alternation test was used to score spatial working memory in CD1 mice at four different age categories (young (3-6 months), middle-aged (7-11 months), aged (12-18 months) and old (>19 months). TPL performance of middle-aged and aged CD1 mice was tested in a setup with either two or three time points per day (2-arm or 3-arm TPL task). Immunostainings were applied on brains of young and middle-aged C57Bl/6 mice that had successfully mastered the 3-arm TPL task.Results: In contrast to C57Bl/6 mice, middle-aged and aged CD1 mice were less hippocampus-driven and failed to master the 3-arm TPL task. They could, however, master the 2-arm TPL task primarily via an ordinal (non-circadian) timing system. c-Fos, CRY2, vasopressin (AVP), and phosphorylated cAMP response element-binding protein (pCREB) were investigated. We found no differences at the level of the suprachiasmatic nucleus (SCN; circadian master clock), whereas CRY2 expression was increased in the hippocampal dentate gyrus (DG). The most pronounced difference between TPL trained and control mice was found in c-Fos expression in the paraventricular thalamic nucleus, a circadian system relay station.Conclusions: These results further indicate a key role of CRY proteins in TPL and confirm the limited role of the SCN in TPL. Based on the poor TPL performance of CD1 mice, the results suggest age-sensitivity and hippocampal involvement in TPL. We suspect that TPL reflects an episodic-like memory task, but due to its functional nature, also entail the translation of experienced episodes into semantic rules acquired by training.
- Subjects :
- 0301 basic medicine
Cognitive Neuroscience
AGED RATS
Hippocampus
Hippocampal formation
Spatial memory
lcsh:RC321-571
memory
03 medical and health sciences
Behavioral Neuroscience
0302 clinical medicine
VASOPRESSIN-IMMUNOREACTIVE CELLS
place
clock genes
Circadian rhythm
C-FOS EXPRESSION
lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry
time
Original Research
EFFERENT PROJECTIONS
RAT SUPRACHIASMATIC NUCLEUS
learning
Suprachiasmatic nucleus
cry
Dentate gyrus
aging
Spontaneous alternation
ELEMENT-BINDING PROTEIN
NERVOUS-SYSTEM
030104 developmental biology
Neuropsychology and Physiological Psychology
circadian
DENTATE GYRUS
CIRCADIAN CLOCKS
Episodic-like memory
TEMPORAL-ORDER
Psychology
Neuroscience
030217 neurology & neurosurgery
Subjects
Details
- Language :
- English
- ISSN :
- 16625153
- Volume :
- 9
- Database :
- OpenAIRE
- Journal :
- Frontiers in Behavioral Neuroscience
- Accession number :
- edsair.doi.dedup.....9d3ad06c1c8c04ec92ecf859102347e3
- Full Text :
- https://doi.org/10.3389/fnbeh.2015.00362