The broad goal of the proposed studies is to gain a better understanding of the human mirror system. Mirror neurons have been proposed to play a central role in the neural mechanisms of action understanding, imitation, empathy, and use of language. It is, therefore, of exceptional interest to study their distribution and function in humans. Mirror neurons are functionally unique in that they respond during both the observation and the execution of specific movements. Importantly, they, respond selectively to a preferred movement and not others. Mirror neurons are, therefore, expected to exist in cortical areas that exhibit movement selective fMRI responses for observed and executed movements. In this proposal the applicant describes two new experimental fMRI protocols for identifying such areas. The first experimental protocol utilizes an fMRI adaptation approach and the second utilizes a multivariate pattern classification approach. Subjects will play the rock paper scissors game against a virtual opponent while being scanned. They will observe and execute the game movements repeatedly over many trials. To assess movement selective adaptation in the first experiment, responses on trials where observed or executed movements were repeated will be compared with trials where they were not. In the second experiment each observed and executed movement will be classified with its fMRI spatial response pattern and classification accuracy will be used to assess underlying movement selectivity of the examined cortical areas. Subjects will also participate in variants of the imitation and movement observation experiments previously used to localize candidate mirror areas. Results from these four independent methodologies for localizing candidate mirror areas will be compared to reveal a clearer picture of the human mirror system. In a final study all four methodologies will be employed to assess mirror system function in autistic individuals and matched controls. This study will test the hypothesis that dysfunctions of mirror neurons may be the underlying cause of multiple autistic symptoms. The proposed studies will lead to improved diagnostic, prognostic, and therapeutic procedures for autism as well as for other disorders including schizophrenia and psychopathy, which have also been linked with mirror system dysfunctions.