Neuronal activity shows link between wakefulness, fight-or-flight response in mice

Researchers have revealed a role for orexin neurons of the hypothalamus in regulating the response to harmful stimuli in mice. Painful stimuli activated orexin neurons, except in mice that were anesthetized. Mice bred to lack orexin neurons were hypersensitive to such stimuli, while those with artificially activated orexin neurons demonstrated reduced responses to pain. These findings suggest a link between response to stimuli and consciousness that is regulated by neurons producing orexin.