Mid-Term Report Summary - C.O.C.O. (Circuits of con-specific observation)
A great deal is known about the neural basis of associative fear learning. However, many animal species are able to use social cues to recognize threats, a defence mechanism that may be less costly than learning from self-experience. We have previously shown that rats perceive the cessation of movement-evoked sound as a signal of danger and its resumption as a signal of safety. To study transmission of fear between rats we assessed the behavior of an observer while witnessing a demonstrator rat display fear responses. With this paradigm we are taking advantage of the accumulated knowledge on learned fear to investigate the neural mechanisms by which the social environment regulates defense behaviors. We are currently unravelling the neural circuits involved in detecting the transition from movement-evoked sound to silence. To this end, we combine immunohistochemistry, pharmacology and optogenetics. We have found that the lateral amygdala, crucial for fear learning, is required for silence-triggered freezing and are currently studying the auditory inputs that might drive the amygdala upon the cessation of movement-evoked sound. Moreover, since observer rats previously exposed to shock display observational freezing, but naive observer rats do not, we aim to determine the mechanism by which prior experience contributes to observational freezing. Evidence from our lab indicates that stress induced sensitization is not sufficient to facilitate observational freezing and that freezing in association which shock may be important for this process. Finally, as the detection of and responses to threat are often inherently social, we are studying these behaviors in the context of large groups of individuals. To circumvent the serious limitations in using large populations of rats, we will resort to a different model system. The fruit fly is the ideal model system, as it is amenable to the search for the neural mechanism of behavior, while at the same time allowing the study of the behavior of large groups of individuals. We have developed a behavioral task, that allows studying freezing behaviour in flies, triggered by a threatening stimulus, and its modulation by social interactions.
Tania Vinagre, (Director)
Record Number: 189650 / Last updated on: 2016-10-13