Scientists in Shanghai say they've found a way to erase the brain's association of fear with certain sounds.

Their findings could open up new methods to cure post-traumatic stress and anxiety disorders. A particular pathway in the brain, and the suppression of its activity, can lead to reduction in fear responses.

Research results were published on the website of the journal Nature Neuroscience on Sept 5.

The researchers, from the Institute of Neuroscience, a branch of Shanghai Institutes for Biological Sciences under the Chinese Academy of Sciences, tested their hypothesis on mice. They played a certain sound and delivered a simultaneous electric shock. The mice learned to associate the sound with the shock and exhibited fear responses whenever the sound was played, even when no shock was delivered.

"When we used methods such as optogenetics and chemogenetics to selectively reduce the neural activity on this pathway, the fear responses exhibited by the mice were greatly reduced. They will be active as usual when hearing the sound instead of freezing with fear," said Yang Yang, a researcher on the team.

The pathway is found between the amygdala, a tiny area in the brain that reacts to threats in one's environment, and the auditory sensory area called the auditory cortex, Yang said.

She said the research result is of great significance because a similar pathway is known to exist in the brains of primates.

If the corresponding pathway can be found in the human brain and similar interventions are implemented, people who suffer from anxiety disorder and PTSD brought by fearful memories will be relieved, Yang said.

Mu-Ming Poo, the lead researcher for the project and director of the institute, said the possible clinical applications of the research could conceivably serve as a substitute for the current underdeveloped drug therapies for brain diseases.

"Medicines in this area have poor specificity, as well as visible side effects such as damage to other brain functions. Scientists and doctors have been looking for such noninvasive means to help sufferers of mental disorders recover," Poo said.