'Freezing' is a part of the fear response

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COLD SPRING HARBOR LABORATORY, N.Y., Jan. 31 (UPI) -- U.S. scientists say they have a better understanding of how "freezing" is part of the fear response.

Study leader Bo Li, assistant professor, and Professor Z. Josh Huang of the Cold Spring Harbor Laboratory examined the how fear responses are learned, controlled and memorized.

They show that a particular class of neurons in a subdivision of the amygdala -- part of the brain that processes memory and emotional reactions -- might be part of the circuit that controls fear learning and memory.

In particular, a region called the central amygdala was thought to be a passive relay for the signals relayed within this circuit.

Li and colleagues observed neurons in a region of the central amygdala called the lateral subdivision, "lit up" in a particular strain of mice while studying this circuit.

"Neuroscientists believed that changes in the strength of the connections onto neurons in the central amygdala must occur for fear memory to be encoded, but nobody had been able to actually show this," Li said in a statement. "We find that the fear memory in the central amygdala can modify the circuit in a way that translates into action -- or what we call the fear response."

The findings were published in Nature Neuroscience.