IMMEDIATE-EARLY GENE-EXPRESSION ASSOCIATED WITH THE PERSISTENCE OF HETEROSYNAPTIC LONG-TERM DEPRESSION IN THE HIPPOCAMPUS

Citation
Wc. Abraham et al., IMMEDIATE-EARLY GENE-EXPRESSION ASSOCIATED WITH THE PERSISTENCE OF HETEROSYNAPTIC LONG-TERM DEPRESSION IN THE HIPPOCAMPUS, Proceedings of the National Academy of Sciences of the United Statesof America, 91(21), 1994, pp. 10049-10053
Citations number
27
Categorie Soggetti
Multidisciplinary Sciences
ISSN journal
00278424
Volume
91
Issue
21
Year of publication
1994
Pages
10049 - 10053
Database
ISI
SICI code
0027-8424(1994)91:21<10049:IGAWTP>2.0.ZU;2-S
Abstract
Long-term depression (LTD) of synaptic efficacy is likely to be as imp ortant in memory processing as the more well-known long-term potentiat ion (LTP). The case for LTD serving as a memory mechanism, however, re quires that it be shown to persist across days or weeks at least. Here we examined the persistence of heterosynaptic LTD in the medial and l ateral perforant path inputs to the dentate gyrus in awake rats and co rrelated this persistence with the degree of immediate early gene expr ession as assessed immunohistochemically. Rats were chronically implan ted with separate stimulating electrodes in the medial and lateral per forant paths and an extracellular field potential recording electrode in the dentate hilus. After recovery from surgery, either the medial o r the lateral perforant path was tetanized with 400-Hz trains, and hom osynaptic LTP and heterosynaptic LTD were followed across time. Hetero synaptic LTD was shown to occur readily in awake animals and to persis t across days or weeks, depending on the stimulation protocol. The per sistence of LTD and LTP was highly correlated within animals. Addition al animals, given the same tetanization protocols, showed that the gre atest immediate early gene expression occurred following that protocol which consistently gave the longest lasting LTP and LTD. These data s upport the proposed role of LTD in memory processing but question whet her immediate early genes are important for the persistence of LTP, LT D, or both.