Learning a threat converges on the circuit processing innate threat

Conventional wisdom in affective neuroscience posits that innate and learned responses are processed through separate neuroanatomical channels – one hardwired, the other reliant on synaptic plasticity. However, recent research suggests that the processing of innate and acquired threats in the lateral amygdala challenges this long-held notion.

By monitoring the three fundamental components of circuit function – excitatory neurons, inhibitory neurons, and neuromodulators – in mice, scientists observed a significant difference in the way the brain responds to natural versus learned threats. As these creatures encountered an inborn aversive stimulus and subsequently underwent auditory threat training, researchers identified a group of excitatory neurons that responded more robustly to the innate threat.

Crucially, these same neurons exhibited enhanced activity following auditory threat learning. Both forms of threat were found to converge on comparable modulatory mechanisms, namely the disinhibitory VIP/SST circuitry and norepinephrine release. Nonetheless, a key distinction emerged: while the innate threat had exclusive access to these pathways, the learned cue gained entry via synaptic plasticity.

This discovery reveals that learning about a new threat seemingly activates a circuitry designed to shield animals from natural dangers.