Instrumental aversion coding in the basolateral amygdala and its reversion by a benzodiazepine

Area of Science:

• Neuroscience
• Behavioral Science
• Molecular Biology

Background:

• Punishment learning, crucial for survival, involves understanding actions and consequences.
• The basolateral amygdala (BLA) is vital for both acquiring and expressing punishment learning.
• The precise neural mechanisms by which the BLA supports punishment remain unclear.

Purpose of the Study:

• To investigate how principal neurons in the basolateral amygdala (BLA) support punishment learning.
• To elucidate the neural activity patterns in the BLA during the acquisition and expression of punishment.

Main Methods:

• Calcium (Ca2+) imaging using GCaMP6f in BLA principal neurons of male rats.
• Training rats to lever-press for food, with one lever also delivering footshock (punishment).
• Analyzing BLA neural activity in response to rewards, footshock, and punished/unpunished lever presses.

Main Results:

• BLA neurons showed excitatory activity to footshock and inhibitory activity to reward-associated lever presses.
• During punishment learning, BLA activity shifted from inhibitory to excitatory for punished responses.
• Punished response-related BLA activity became similar to BLA responses to the footshock punisher.
• Systemic administration of midazolam (a benzodiazepine) selectively reduced punishment behavior.
• The extent to which midazolam alleviated punishment correlated with the reversion of punished response-related BLA activity to its pre-punishment state.

Conclusions:

• Punishment learning is mediated by the BLA's aversion coding of instrumental responses.
• Benzodiazepines alleviate punishment by reversing this aversion coding in the BLA.
• These findings offer insights into the neural basis of aversion and the mechanisms of benzodiazepine action.