The experiment included three parts: facial expressions, grasping and a control experiment. Activity from a total of 1,177 neurons in the 21 patients was recorded as the patients both observed and performed grasping actions and facial gestures. In the observation phase, the patients observed various actions presented on a laptop computer. In the activity phase, the subjects were asked to perform an action based on a visually presented word. In the control task, the same words were presented and the patients were instructed not to execute the action.
The researchers found that the neurons fired or showed their greatest activity both when the individual performed a task and when they observed a task. The mirror neurons making the responses were located in the medial frontal cortex and medial temporal cortex, two neural systems where mirroring responses at the single-cell level had not been previously recorded, not even in monkeys.
This new finding demonstrates that mirror neurons are located in more areas of the human brain than previously thought. Given that different brain areas implement different functions in this case, the medial frontal cortex for movement selection and the medial temporal cortex for memory the finding also suggests that mirror neurons provide a complex and rich mirroring of the actions of other people.
Because mirror neurons fire both when an individual performs an action and when one watches another individual perform that same action, it's thought this "mirroring" is the neural mechanism by which the actions, intentions and emotions of other people can be automatically understood.
"The study suggests that the distribution of these unique cells linking the activity of the self with that of others is wider than previously believed," said Fried, the study's senior author and director of the UCLA Epilepsy Surgery Program.
|Contact: Mark Wheeler|
University of California - Los Angeles