RT Journal Article SR Electronic T1 Activation of the Medial Septum Reverses Age-Related Hippocampal Encoding Deficits: A Place Field Analysis JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 1841 OP 1853 DO 10.1523/JNEUROSCI.4629-07.2008 VO 28 IS 8 A1 Simona Sava A1 Etan J. Markus YR 2008 UL http://www.jneurosci.org/content/28/8/1841.abstract AB When a rat runs through a familiar environment, the hippocampus retrieves a previously stored spatial representation of the environment. When the environment is modified a new representation is seen, presumably corresponding to the hippocampus encoding the new information. The medial septum is hypothesized to modulate whether the hippocampus engages in retrieval or encoding. The cholinergic agonist carbachol was infused into the medial septum, and hippocampal CA1 place cells were recorded in freely moving rats. In a familiar environment, septal activation impaired the retrieval of a previously stored hippocampal place cell representation regardless of age. When the environment was changed, medial septal activation impaired the encoding process in young, but facilitated the encoding of the new information in aged rats. Moreover, the improved encoding was evident during a subsequent exposure to the modified environment 24 h later. The findings support the role the septum plays in modulating hippocampal retrieval/encoding states. Furthermore, our data indicate a mechanism of age-related cognitive impairment.