Involvement of the insular cortex in the consolidation and expression of contextual fear conditioning

The insular cortex (IC) has been reported to be involved in the modulation of memory and autonomic and defensive responses. However, there is conflicting evidence about the role of the IC in fear conditioning. To explore the IC involvement in both behavioral and autonomic responses induced by contex...

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Veröffentlicht in:The European journal of neuroscience 2013-07, Vol.38 (2), p.2300-2307
Hauptverfasser: Alves, Fernando H. F., Gomes, Felipe V., Reis, Daniel G., Crestani, Carlos C., Corrêa, Fernando M. A., Guimarães, Francisco S., Resstel, Leonardo B. M.
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Sprache:eng
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Zusammenfassung:The insular cortex (IC) has been reported to be involved in the modulation of memory and autonomic and defensive responses. However, there is conflicting evidence about the role of the IC in fear conditioning. To explore the IC involvement in both behavioral and autonomic responses induced by contextual fear conditioning, we evaluated the effects of the reversible inhibition of the IC neurotransmission through bilateral microinjections of the non‐selective synapse blocker CoCl2 (1 mm) 10 min before or immediately after the conditioning session or 10 min before re‐exposure to the aversive context. In the conditioning session, rats were exposed to a footshock chamber (context) and footshocks were used as the unconditioned stimulus. Forty‐eight hours later, the animals were re‐exposed to the aversive context for 10 min, but no shock was given. Behavioral (freezing) as well as cardiovascular (arterial pressure and heart rate increases) responses induced by re‐exposure to the aversive context were analysed. It was observed that the local IC neurotransmission inhibition attenuated freezing and the mean arterial pressure and heart rate increase of the groups that received the CoCl2 either immediately after conditioning or 10 min before re‐exposure to the aversive context, but not when the CoCl2 was injected before the conditioning session. These findings suggest the involvement of the IC in the consolidation and expression of contextual aversive memory. However, the IC does not seem to be essential for the acquisition of memory associated with aversive context. The IC microinjection of CoCl2, either after the conditioning session or before the test session, attenuated the behavioral (freezing) and cardiovascular responses evoked by the re‐exposure to an aversively conditioned context. However, the inactivation of the IC did not impair the acquisition of the contextual fear memory when CoCl2 was microinjected before the conditioning session. These results suggest the involvement of IC in both the consolidation and expression of contextual fear memory.
ISSN:0953-816X
1460-9568
DOI:10.1111/ejn.12210