The entorhinal cortex modulates trace fear memory formation and neuroplasticity in the lateral amygdala via cholecystokinin

Although the neural circuitry underlying fear memory formation is
important in fear-related mental disorders, it is incompletely understood.
Here, we utilized trace fear conditioning to study the formation of trace
fear memory. We identified the entorhinal cortex (EC) as a critical
component of sensory signaling to the amygdala. Moreover, we used the loss
of function and rescue experiments to demonstrate that release of the
neuropeptide cholecystokinin (CCK) from the EC is required for trace fear
memory formation. We discovered that CCK-positive neurons extend from the
EC to the lateral nuclei of the amygdala (LA), and inhibition of
CCK-dependent signaling in the EC prevented long-term potentiation of
sensory signals to the LA and formation of trace fear memory. Altogether,
we suggest a model where sensory stimuli trigger the release of CCK from
EC neurons, which potentiates sensory signals to the LA, ultimately
influencing neural plasticity and trace fear memory formation.