The Molecular Substrates of Second-Order Conditioned Fear in the Basolateral Amygdala Complex

Area of Science:

• Neuroscience
• Molecular Biology
• Behavioral Psychology

Background:

• Fear conditioning involves gene expression in the basolateral amygdala (BLA) for memory consolidation.
• Second-order fear conditioning, unlike first-order, is not inhibited by protein synthesis blockers in the BLA.

Purpose of the Study:

• To identify immediate early genes regulating second-order fear conditioning in the BLA.
• To investigate the roles of BDNF and EGR1 in fear acquisition, consolidation, and reconsolidation.

Main Methods:

• Principal components analysis of PCR data to identify gene networks.
• Infusions of antisense oligonucleotides targeting BDNF and EGR1 in the BLA.
• Behavioral assays for first- and second-order fear conditioning and reconsolidation.

Main Results:

• Second-order fear conditioning involves region- and time-specific changes in genes including BDNF and EGR1.
• BDNF is essential for consolidating both first- and second-order fears, but not reconsolidation.
• EGR1 is required for second-order fear acquisition and reconsolidation of both fear types, but not first-order consolidation.

Conclusions:

• BDNF and EGR1 differentially regulate distinct aspects of fear conditioning and memory in the BLA.
• Immediate early genes play crucial roles in complex fear information processing within the amygdala.
• Findings contribute to understanding novel information-processing mechanisms in the mammalian brain.