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Hippocampal place cells as a window into cognitive aging
| Content Provider | Semantic Scholar |
|---|---|
| Author | Wilson, Iain A. |
| Copyright Year | 2005 |
| Abstract | As scientific and medical advances allow humans to live longer and physically healthier lives, it becomes increasingly important to maintain mental well-being in old age. Among the normal aging population, or those spared from the devastation of neurodegenerative diseases, there exists considerable variability in the cognitive ability to learn and remember new information. This study investigates the mechanisms underlying why some people suffer from age-associated memory impairments, whereas others remain as cognitively adept as young people. This study examined the hippocampal spatial representations of a rat model of cognitive aging characterized by heterogeneous abilities on learning and memory tasks. The spatial memory capacity of young and aged rats was first characterized on the Morris water maze task. Then the firing patterns of hippocampal CA1 and CA3 pyramidal cells were recorded as the rats explored both familiar and novel environments. These "place cells” are highly active when a rat occupies particular places within an environment, and they thus serve as a window into spatial information processing. The neurons of young and memory-intact aged rats used different spatial firing patterns to represent the familiar and the visually novel environments, and their cells rotated with rotations of the arena landmarks on every occasion. The aged memoryimpaired rats, on the other hand, initially used the same place cell firing patterns to represent both the familiar and visually novel arenas, and even after new spatial representations were created, their cells failed to rotate with the landmarks on many but not all occasions, including the first rotation experiment. Furthermore, the extent of these hippocampal failures correlated with the degree of memory impairment in the rats. In subsequent analyses the place cells of the aged CA3 subregion, in particular, had higher firing rates and failed to rapidly encode changes to the external environment in comparison to young CA3 cells. CA1 place cell properties, on the other hand, were similar for aged and young rats. In a further experiment the same rats walked between two visually identical environments, pitting self-motion cues that indicated change against visual inputs that indicated no differences between environments. Now place cells of young and aged rats were equally likely to create new spatial representations in second compartment, suggesting that the hippocampus of aged rats is able to process changes in internallygenerated cues without rigidity. These results suggest that age-related spatial memory impairments may arise from incomplete processing of external visual landmarks, coinciding with a proclivity towards self-motion cues, and a hyperactivity and a weakened encoding of novelty specific to the CA3 subregion. National Library of Medicine Classification: WT104; WL314 Medical Subject Headings: hippocampus; aging / physiology; memory / physiology; spatial behavior; rats; maze learning; cholinergic fibers; models, animal; cognition |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www2.uef.fi/documents/1085457/1371730/76the.pdf/ff6b9b3f-4f43-481d-b673-451e74b05c4a |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
