RESUMEN
Predators must frequently balance competing approach and defensive behaviors elicited by a moving and potentially dangerous prey. Several brain circuits supporting predation have recently been localized. However, the mechanisms by which these circuits balance the conflict between approach and defense responses remain unknown. Laboratory mice initially show alternating approach and defense responses toward cockroaches, a natural prey, but with repeated exposure become avid hunters. Here, we used in vivo neural activity recording and cell-type specific manipulations in hunting male mice to identify neurons in the lateral hypothalamus and periaqueductal gray that encode and control predatory approach and defense behaviors. We found a subset of GABAergic neurons in lateral hypothalamus that specifically encoded hunting behaviors and whose stimulation triggered predation but not feeding. This population projects to the periaqueductal gray, and stimulation of these projections promoted predation. Neurons in periaqueductal gray encoded both approach and defensive behaviors but only initially when the mouse showed high levels of fear of the prey. Our findings allow us to propose that GABAergic neurons in lateral hypothalamus facilitate predation in part by suppressing defensive responses to prey encoded in the periaqueductal gray. Our results reveal a neural circuit mechanism for controlling the balance between conflicting approach and defensive behaviors elicited by the same stimulus.
Asunto(s)
Hipotálamo/fisiología , Conducta Predatoria , Animales , Neuronas GABAérgicas/fisiología , Hipotálamo/citología , Masculino , Ratones , Ratones Endogámicos C57BL , Vías NerviosasRESUMEN
Social aggression and avoidance are defensive behaviors expressed by territorial animals in a manner appropriate to spatial context and experience. The ventromedial hypothalamus controls both social aggression and avoidance, suggesting that it may encode a general internal state of threat modulated by space and experience. Here, we show that neurons in the mouse ventromedial hypothalamus are activated both by the presence of a social threat as well as by a chamber where social defeat previously occurred. Moreover, under conditions where the animal could move freely between a home and defeat chamber, firing activity emerged that predicted the animal's position, demonstrating the dynamic encoding of spatial context in the hypothalamus. Finally, we found that social defeat induced a functional reorganization of neural activity as optogenetic activation could elicit avoidance after, but not before social defeat. These findings reveal how the hypothalamus dynamically encodes spatial and sensory cues to drive social behaviors.
Asunto(s)
Agresión/fisiología , Hipotálamo , Conducta Espacial/fisiología , Animales , Hipotálamo/citología , Hipotálamo/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , OptogenéticaRESUMEN
The neural circuits mediating fear to naturalistic threats are poorly understood. We found that functionally independent populations of neurons in the ventromedial hypothalamus (VMH), a region that has been implicated in feeding, sex and aggression, are essential for predator and social fear in mice. Our results establish a critical role for VMH in fear and have implications for selective intervention in pathological fear in humans.