Head west or left, east or right: interactions between memory systems in neurocognitive aging.
Cognitive aging is accompanied by decline in multiple domains of memory. Here, we developed a T-maze task that required rats to learn competing hippocampal, and striatal navigation strategies in succession, across days. A final session increased demands on cognitive flexibility and required within-day switching between strategies, emphasizing capacities that engage the prefrontal cortex. Background characterization in young and aged rats used a water maze protocol optimized for individual differences in hippocampal integrity. Consistent with earlier work, young adults acquired place strategies in the T-maze faster than response, whereas the opposite was observed in aged rats with impaired spatial memory. The novel result was that aged animals with preserved spatial memory displayed a qualitatively distinct pattern, acquiring place and response strategies equally rapidly, without disruption when switching between them. Subsequent in situ hybridization for the plasticity-related immediate-early gene Arc revealed that while increasing demands on cognitive flexibility and within-day strategy switching potently engaged the prefrontal cortex in young adult and aged-impaired rats, Arc expression was insensitive in aged rats with normal spatial memory and superior switching abilities. Together, the results indicate that cognitive aging is an emergent property of the interactions between memory systems, and that successful cognitive outcomes reflect a distinct neuroadaptive process rather than a slower rate of aging.
Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, NIH, Baltimore, MD, USA.
Inês
I
Tomás Pereira
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
Michela
M
Gallagher
Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, NIH, Baltimore, MD, USA. Electronic address: rappp@mail.nih.gov.
Peter R
PR
Rapp
D000375:Aging / Q000523:psychology*; D000818:Animals; D003071:Cognition / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000502:physiology; D017781:Genes, Immediate-Early; D006624:Hippocampus / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology; D020318:Rats, Long-Evans; D065852:Spatial Memory / Q000502:physiology*; D065854:Spatial Navigation / Q000502:physiology
D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C092069:activity regulated cytoskeletal-associated protein
Arc; Hippocampus; Memory systems; Neuroadaptive aging; Prefrontal cortex; Rat