Boffins identify tiny brain area key to fear of rivals and predators

Washington, Mar 10 (ANI): Researchers from University of Southern California have identified an area of hypothalamus in the brain, which is key to animals' fear of territorial rivals and predators.

The team of neurologists led by Larry Swanson found that mice lose their fear of territorial rivals when a tiny piece of their brain is neutralized.

Brain's amygdala region has long been studied by researchers as the region of fear. However, the new study has shown that primal fear responses do not depend on the amygdala, but on an obscure corner of the primeval brain.

During the study, the researchers examined the brain activity of rats and mice exposed to cats, or to rival rodents defending their territory.

They found that both experiences activated neurons in the dorsal premammillary nucleus, part of an ancient brain region called the hypothalamus.

For further analysis, the research team then made tiny lesions in the same area. Those rodents behaved far differently.

"These animals are not afraid of a predator," Swanson said.

"It's almost like they go up and shake hands with a predator.

"It's amazing that these lesions appear to abolish innate fear responses.

"The same basic circuitry is found in primates and people that we find in rats and mice," he added.

The study appears in Proceedings of the National Academy of Sciences. (ANI)