Human brain mapping
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To assess the relationship between the mirror-neuron system (MNS), an observation-execution matching system, and handedness, we acquired functional magnetic resonance imaging from 11 right-handed (RH) and eight left-handed (LH) subjects to identify regions involved in processing action (execution and observation) of the right and left upper limbs. During the execution tasks, LH subjects had a more bilateral pattern of activation than RH. An interaction between handedness and hand observed during the observation conditions was detected in several areas of the MNS and the motor system. ⋯ During the execution task with the nondominant limbs, both groups activated regions of the MNS and motor system. Albeit this study is based on a small sample, the patterns of MNS activations observed in RH and LH subjects support the theory that suggests that this system is involved in brain functions lateralization. In LH people, this system might contribute to their adaptation to a world essentially built for right-handers through a mechanism of mirroring and imitation.