The basolateral amygdala complex and perirhinal cortex represent focal and peripheral states of information processing in rats

We previously identified the roles of the basolateral amygdala complex (BLA) and perirhinal cortex (PRh) in sensory preconditioning in male and female rats (Wong et al., 2025). Here, we used variations of a sensory preconditioning protocol to test a general theory that the BLA and PRh represent focal and peripheral states of attention, respectively. We specifically tested predictions derived from the theory regarding when learning about a stimulus that signals danger will be disrupted by BLA or PRh infusions of the N -methyl-D-aspartate receptor (NMDAR) antagonist, DAP5. Consistent with the theory, the effects of these infusions depended on the novelty/familiarity of the conditioned stimulus, as well as the manner in which it was paired with foot shock. When a stimulus was novel, its conditioning required NMDAR-activation in the BLA and not the PRh, regardless of whether the stimulus and shock were presented contiguously or separated in time. When a pre-exposed and, thereby, familiar stimulus was presented contiguously with shock, its conditioning again required NMDAR-activation in the BLA and not the PRh. However, when a pre-exposed stimulus was indirectly paired with shock – because it was associatively activated at the time of shock or separated from the shock by another stimulus – its conditioning required NMDAR-activation in the PRh and not the BLA. These findings are discussed in relation to theories of information processing that distinguish between focal and peripheral states of attention/memory, and past studies that have examined the substrates of learning and memory in the PRh and BLA.