Neurobiological processes via which BF amygdalopetal cholinergic neurons modulate emotional memory. A) Hypothetical circuit. Circles in red illustrate locus coeruleus neurons, green represent BF amygdalopetal cholinergic neurons, purple represent BLA principal neurons, and orange represent cortical input to BLA principal neurons. Components of the circuit that need verification are shown in dashed lines. B) Molecular processes by which BF amygdalopetal cholinergic neurons modulate emotional memory. Unknown mechanisms are shown as question marks or dashed lines. Decreased signaling is indicated by light blue arrows. C) Fear relevant electrophysiological processes by which BF amygdalopetal cholinergic neurons modulate BLA principal neurons. LC – locus coeruleus. m1AChR – muscarinic receptor type 1, nAChR – nicotinic receptor, IP3 – inositol triphosphate, IP3R – IP3 receptor, DAG – diacylglycerol, PIP2 – phosphatidylinositol biphosphate, PKC – protein kinase C.