The expression “once bitten, twice shy” is an illustration of how a bad experience can induce fear and caution. How to effectively reduce the memory of aversive events is a fundamental question in neuroscience. Scientists in China are reporting that by transplanting mouse embryonic interneurons into the brains of mice and combining that procedure with training to lessen fear, they can help to reduce the fear response.
The research is in Neuron. (full access paywall)