Fear extinction requires Arc/Arg3.1 expression in the basolateral amygdala

Area of Science:

• Neuroscience
• Molecular Biology
• Behavioral Science

Background:

• Fear extinction, a process of reducing fear responses through cue re-exposure without negative consequences, is a basis for exposure therapy.
• Arc (Arg3.1) is a gene involved in synaptic plasticity and is regulated by cAMP response element binding protein, which is crucial for fear extinction.
• Arc expression increases during fear extinction, suggesting a potential role in this process.

Purpose of the Study:

• To investigate the necessity of Arc gene expression for fear extinction.
• To determine if Arc plays a role in the formation of long-term extinction memory.

Main Methods:

• Extinction training was conducted on subjects exposed to fear-eliciting cues.
• The proportion of Arc-labeled cells in the basolateral amygdala (BLA) was quantified.
• Arc antisense oligodeoxynucleotide (ODN) was infused into the BLA before or after extinction training to inhibit Arc expression.

Main Results:

• Extinction training led to an increased proportion of Arc-labeled cells in the BLA, with Arc transcription occurring during both early and late phases of training.
• Infusion of Arc antisense ODN into the BLA prior to extinction training significantly impaired long-term extinction memory but not short-term memory.
• Infusion of Arc antisense ODN 3 hours after extinction training had no effect on fear extinction.

Conclusions:

• Arc expression is a critical molecular mechanism required for the consolidation of long-term extinction memory.
• These findings enhance the understanding of the molecular underpinnings of extinction and its therapeutic potential in fear-related disorders.