External Behavior Monitoring Mirrors Internal Behavior Monitoring

The discovery of mirror neurons in monkeys has reshaped thinking about how the brain processes observed actions. There is growing evidence that these neurons, which show similar firing patterns for action execution and observation, also exist in humans. Many parts of the motor system required to perform a specific action are activated during the observation of the same action. We hypothesized that behavior monitoring that occurs during action execution is mirrored during action observation. To test this, we measured error negativity/error-related negativity (Ne/ERN) while participants performed and observed a Go/NoGo task. The Ne/ERN is an event-related potential that is thought to reflect an error detection process in the brain. In addition to finding an Ne/ERN for performed errors, we found that an Ne/ERN was also generated for observed errors. The Ne/ERN for observed errors may reflect a system that plays a key role in imitation and observational learning.