Intense threat moves serotonin neurons from the raphe dorsal into a paradoxical mode of operation

Reverse behavior under threat

Could it be that the brain in a state of emergency or under intense threat operates in a fundamentally different way? Seo et al. found that the mice were paused when serotonin neurons were transiently stimulated in low to medium threat environments, but when this same population of neurons was stimulated in high-risk environments, mice tried to 39; escape. The recordings of these neurons indicate that the movement-related neural setting switches between environments. Neuronal activity decreased when movement was initiated in low-risk environments, but increased in high-risk environments.

Science, this number p. 538

Abstract

Survival depends on the choice of adaptive behaviors in the current environment. For example, a mouse must run from a hawk that is looming fast, but should freeze if the hawk sneaks into the sky. Although serotonin has been implicated in adaptive behavior, the environmental regulation of its functional role remains poorly understood. In mice, we found that stimulation of serotonin neurons in the dorsal raphe suppressed movement in low to moderate threat environments, but induced escape behavior in high threat environments, and neuronal dynamics. serotonin dorsal raphe movement was reversed in high threat environments. Stimulation of the dorsal raphe GABA (gamma-aminobutyric acid) neurons promotes movement in negative but non-positive environments, and movement-related GABA neural dynamics are reversed between positive and negative environments. Thus, back raphe circuits switch between distinct modes of operation to promote adaptive behaviors specific to the environment.