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No use, distribution or reproduction is permitted which does not comply with these terms. Cholinergic cells have been proposed to innervate simultaneously those cortical areas that are mutually interconnected with each other. To test this hypothesis, we investigated the cholinergic innervation of functionally linked amygdala and prefrontal cortical regions. First, using tracing experiments, we determined that cholinergic cells located in distinct basal forebrain BF areas projected to the different nuclei of the basolateral amygdala BLA.
In addition, cholinergic neurons in these two BF areas gave rise to overlapping innervation in the medial prefrontal cortex mPFC , yet their axons segregated in the dorsal and ventral regions of the PFC. Using retrograde-anterograde viral tracing, we demonstrated that a portion of mPFC-projecting cholinergic neurons also innervated the BLA, especially the BA. The dual innervation strategy, i. The presence of VGLUT3 in a portion of cholinergic afferents suggests more complex functional effects of cholinergic system in cortical structures.
Recognizing threats is essential for animal survival. Therefore, it is not surprising that many brain circuits contribute to the detection of dangerous situations, leading to the elevation of attention and promoting affective brain state linked to the threat Davis, ; LeDoux, ; Tovote et al. This danger-triggered mental state helps generating the most appropriate behavioral responses, aiming to avoid, or at least, reduce any potential harm as well as forming memory that can guide future avoidance of similar threat.
These complex brain processes are regulated at different levels in the nervous system. Top-down control is provided by cortical circuits located in the basolateral amygdala BLA and medial prefrontal cortex mPFC; Weiskrantz, ; Mcdonald et al. These two structures can be parceled based on their connectivity and role playing, e. As a general principle, cortical function is efficiently and rapidly affected by subcortical inputs in a brain state-dependent manner.
