The scientists found that a cell-signaling protein, or cytokine, known as a hippocampal TNF (tumor necrosis factor) played a limited role.

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Notably, though by no means exclusively, it accumulates in the hippocampal neurons, where it is associated with the formation of lesions.

ECONOMIST: Dementia

The researchers also saw not only a reduction of hippocampal shrinking in two of the volunteers, but the brain area actually grew by more than 5%.

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Significantly increased hippocampal LTP activity was only recorded in the enriched-environment mice, possibly because exploring novel objects provided both physical exercise and cognitive stimulation, researchers said.

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During hibernation, the levels of tau protein in a squirrel's hippocampal cells are directly correlated with the loss of synapses but not with the appearance of lesions.

ECONOMIST: Dementia