Source Paper
Preserved neuron number in the hippocampus of aged rats with spatial learning deficits.
P R Rapp, M Gallagher
Proceedings of the National Academy of Sciences • 1996
View Abstract
Hippocampal neuron loss is widely viewed as a hallmark of normal aging. Moreover, neuronal degeneration is thought to contribute directly to age-related deficits in learning and memory supported by the hippocampus. By taking advantage of improved methods for quantifying neuron number, the present study reports evidence challenging these long-standing concepts. The status of hippocampal-dependent spatial learning was evaluated in young and aged Long-Evans rats using the Morris water maze, and the total number of neurons in the principal cell layers of the dentate gyrus and hippocampus was quantified according to the optical fractionator technique. For each of the hippocampal fields, neuron number was preserved in the aged subjects as a group and in aged individuals with documented learning and memory deficits indicative of hippocampal dysfunction. The findings demonstrate that hippocampal neuronal degeneration is not an inevitable consequence of normal aging and that a loss of principal neurons in the hippocampus fails to account for age-related learning and memory impairment. The observed preservation of neuron number represents an essential foundation for identifying the neurobiological effects of hippocampal aging that account for cognitive decline.
Morris Water Maze
Objective: Assessment of hippocampal-dependent spatial learning and memory in young and aged rats
This is a Morris Water Maze protocol using rat as the model organism. The procedure involves 2 procedural steps, 1 equipment items. Extracted from a 1996 paper published in Proceedings of the National Academy of Sciences.
Model and subjects
rat • Long-Evans • unknown • young and aged • not specified
Study window
Estimated timing pending
Core workflow
Spatial learning assessment • Neuron quantification
Primary readouts
- Hippocampal-dependent spatial learning performance
- Memory performance
- Total neuron number in dentate gyrus
- Total neuron number in hippocampus
Key equipment and reagents
Verified items
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Direct vendor links
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Protocol Steps
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Spatial learning assessment
Evaluate the status of hippocampal-dependent spatial learning in young and aged Long-Evans rats using the Morris water maze
Note: Testing was conducted on both young and aged subjects
View evidence from paper
“The status of hippocampal-dependent spatial learning was evaluated in young and aged Long-Evans rats using the Morris water maze”
Neuron quantification
Quantify the total number of neurons in the principal cell layers of the dentate gyrus and hippocampus according to the optical fractionator technique
Note: Quantification performed for each hippocampal field
View evidence from paper
“the total number of neurons in the principal cell layers of the dentate gyrus and hippocampus was quantified according to the optical fractionator technique”