Abstract
The periaqueductal gray (PAG) is implicated in numerous defensive responses
such as analgesia, freezing and avoidance. However, which subdivisions and
cell types within the PAG are responsible for these behaviors is not
completely understood. Cholecystokinin-expressing neurons (CCK+) robustly
populate the lateral/ventrolateral PAG, yet they remain largely
uncharacterized. Our early fiber photometry recordings indicate higher
activity in CCK+ l/vlPAG neurons correlates with safety seeking. To probe
the role of these neurons in safety seeking, we developed a Latency To
Enter assay in which a mouse is placed in a box that contains a burrow (a
dark safe space), and the latency (the time taken to enter the burrow) is
measured. A lower latency indicates a stronger safety seeking response.
Optogenetic activation and inhibition of CCK+ l/vlPAG neurons significantly
reduces and increases latency to enter respectively, indicating activity in
these neurons is sufficient and necessary for safety seeking. Together,
these results exhibit the role of CCK+ l/vlPAG neurons in safety seeking,
mapping a specific adaptive response to a genetically-defined PAG neuronal
population.