Detection of novelty, but not memory of spatial habituation, is associated with an increase in phophorylated cAMP response element-binding protein levels in the hippocampus

Abstract

There is a growing body of evidence showing that the formation of associative memories is associated with an increase in phosphorylated cAMP response element-binding protein (pCREB) levels. We recently reported that pCREB level increased in the rat hippocampus after an exploration to a novel environment. In the present work, we studied whether this increment in CREB activation is associated with the formation of memory of habituation to a novel environment or with the detection of novelty. Rats were submitted to consecutive open field sessions at 3 h intervals. Hippocampal pCREB level measurement, performed 1 hour after each training-sessions, revealed that: a) it did not increase when rats explored a familiar environment; b) it did not increase after a re-exposure that improves the memory of habituation; c) it increased after a brief novel exploration unable to form memory of habituation and d) it also increased in amnesic rats for spatial habituation. Taken as a whole, our results suggest that the elevated pCREB level after a single open field exploration is not associated with the memory formation of habituation. It is indeed associated with the detection of a novel environment.