Danger Changes the Way the Brain Consolidates Neutral Information; and Does So by Interacting with Processes Involved in the Encoding of That Information

This study examined the effect of danger on consolidation of neutral information in two regions of the rat (male and female) medial temporal lobe: the perirhinal cortex (PRh) and basolateral amygdala complex (BLA). The neutral information was the association that forms between an auditory stimulus and a visual stimulus (labeled S2 and S1) across their pairings in sensory preconditioning. We show that, when the sensory preconditioning session is followed by a shocked context exposure, the danger shifts consolidation of the S2-S1 association from the PRh to the BLA; and does so by interacting with processes involved in encoding of the S2-S1 pairings. Specifically, we show that the initial S2-S1 pairing in sensory preconditioning is encoded in the BLA and not the PRh; whereas the later S2-S1 pairings are encoded in the PRh and not the BLA. When the sensory preconditioning session is followed by a context alone exposure, the BLA-dependent trace of the early S2-S1 pairings decays and the PRhdependent trace of the later S2-S1 pairings is consolidated in memory. However, when the sensory preconditioning session is followed by a shocked context exposure, the PRh-dependent trace of the later S2-S1 pairings is suppressed and the BLAdependent trace of the initial S2-S1 pairing is consolidated in memory. These findings are discussed with respect to mutually inhibitory interactions between the PRh and BLA, and the way that these regions support memory in other protocols, including recognition memory in people.

Automated summary

The study investigated how danger affects the consolidation of neutral information in the perirhinal cortex (PRh) and basolateral amygdala complex (BLA) of male and female rats. The findings revealed that when a shocked context exposure follows the sensory preconditioning session, the consolidation of the association between the auditory and visual stimuli (S2-S1) shifts from the PRh to the BLA. This shift is influenced by the encoding processes of the S2-S1 pairings. The study also found that the BLA encodes the initial S2-S1 pairing, while the PRh encodes the later pairings. In contrast, when a context alone exposure follows the sensory preconditioning session, the BLA-dependent memory trace of the early pairings decays while the PRh-dependent trace of the later pairings consolidates. However, in the presence of a shocked context exposure, the PRh-dependent memory trace of the later pairings is suppressed, and the BLA-dependent trace of the initial pairings consolidates.