State- and Circuit-Dependent Opponent Processing of Fear.

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Learning and Memory

Background:

• The basolateral amygdala (BLA) contains neurons coding for valence, suggesting opposing roles in reward and aversion learning.
• Evidence for opposing interactions in fear learning is limited, potentially appearing only under specific conditions.

Purpose of the Study:

• To investigate the roles of BLA projections to the central amygdala (CeA) and nucleus accumbens (Acb) in fear learning.
• To determine if these pathways exhibit opponent processing during fear acquisition in different contexts.

Main Methods:

• Assessed the anatomical organization of BLA→CeA and BLA→Acb pathways in male rats.
• Measured pathway activity during fear learning in neutral and reward contexts using footshock as the unconditioned stimulus (US).
• Utilized optogenetic photoinhibition to causally assess pathway roles in fear learning.

Main Results:

• BLA→CeA neurons were recruited by footshock irrespective of context.
• BLA→Acb neuron recruitment was state-dependent, occurring only in a reward context.
• Inhibiting BLA→CeA impaired fear learning universally.
• Inhibiting BLA→Acb augmented fear learning specifically in the reward context.

Conclusions:

• Fear learning involves circuit- and state-dependent opponent processing.
• The BLA→Acb pathway's activity during footshock limits the extent of fear learned, particularly in reward-associated contexts.