A role for the interoceptive insular cortex in the consolidation of learned fear

• The interoceptive insular cortex is required for the long term storage of learned fear in rats.
• The interoceptive insular cortex is not required for the expression of fear during the acquisition of learned fear.
• The long term inactivation of the interoceptive insular cortex decreases the expression of learned fear.
• The expression of conditioned fear increases the neural activity of the insular cortex.

A growing body of evidence suggests that learned fear may be related to the function of the interoceptive insular cortex. Using an auditory fear conditioning paradigm in rats, we show that the inactivation of the posterior insular cortex (pIC), the target of the interoceptive thalamus, prior to training produced a marked reduction in fear expression tested 24 h later. Accordingly, post-training anisomycin infused immediately, but not 6 h after, also reduced fear expression tested the following day, supporting a role for the pIC in consolidation of fear memory. The long-term (ca. a week) and reversible inactivation of the pIC with the sodium channel blocker neosaxitoxin, immediately after fear memory reactivation induced a progressive decrease in the behavioral expression of conditioned fear. In turn, we observed that fear memory reactivation is accompanied by an enhanced expression of Fos and Zif268, early genes involved in neural activity and plasticity. Taken together these data indicate that the pIC is involved in the regulation of fear memories.