Identification of hippocampus-dependent and hippocampus independent memory components in step-down inhibitory avoidance tasks.
Behavioural Brain Research. 2010-02-11; 207(1): 138-143
DOI: 10.1016/j.bbr.2009.09.047
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The aim of this study was to determine if the memory of the association between a step-down response and a foot-shock can be dissociated from the memory of the context in which the shocking experience occurred. To test this, two versions of the step-down inhibitory avoidance task were used: a standard version, in which animals were given one trial with a weak exposure to the context and a new version, in which animals were given a stronger exposure to the context. A retention test was performed with the platform placed either in the same conditioning chamber as during the acquisition phase or in a new context. Our results demonstrate that the step-down inhibitory avoidance can actually be solved without a functional hippocampus. Specifically, the results show that hippocampus-lesioned mice and sham controls can express similar level of memory performance but use two different strategies which were distinguished by assessing retention in a new context. Hippocampus-lesioned mice and mice injected with forskolin (adenylyl cyclase activator) 3h after acquisition use a memory strategy which is independent of the context of acquisition. In addition, our results confirm that the cAMP signaling pathway is a key step in memory consolidation processing.