Hippocampal activation during the recall of remote spatial memories in radial maze tasks.

摘要: Temporally graded retrograde amnesia is observed in human patients with medial temporal lobe lesions as well animal models of lesions. A time-limited role for these structures memory recall has also been suggested by the observation that rodent hippocampus and entorhinal cortex are activated during retrieval recent but not remote memories. One notable exception memories platform locations water maze, which requires an intact results hippocampal activation irrespective age memory. These findings raise question whether always involved spatial or, alternatively, it might be required procedural computations maze task, such calculating a path to hidden platform. We performed testing radial tasks distinguish between possibilities. Radial require choice on center thus have lesser requirement navigation than maze. However, we used behavioral design retained other aspects standard use multiple start retention single trial. Using immediate early gene c-fos marker neuronal activation, found all subregions were more compared In areas CA3 CA1, was higher rats merely reexposed environment after same time interval. Conversely, Fos levels dentate gyrus increased extent corresponding exposure control group. This pattern obtained second version task only arm instead arms. The CA1 consistent interpretation older completion and/or relearning longer intervals. Irrespective recall, engage either support or update