Direct recordings in monkeys have demonstrated that neurons in frontal and parietal areas discharge during execution and perception of actions [1-8]. Because these discharges "reflect" the perceptual aspects of actions of others onto the motor repertoire of the perceiver, these cells have been called mirror neurons. Their overlapping sensory-motor representations have been implicated in observational learning and imitation, two important forms of learning [9]. In humans, indirect measures of neural activity support the existence of sensory-motor mirroring mechanisms in homolog frontal and parietal areas [10, 11], other motor regions [12-15], and also the existence of multisensory mirroring mechanisms in nonmotor regions [16-19]. We recorded extracellular activity from 1177 cells in human medial frontal and temporal cortices while patients executed or observed hand grasping actions and facial emotional expressions. A significant proportion of neurons in supplementary motor area, and hippocampus and environs, responded to both observation and execution of these actions. A subset of these neurons demonstrated excitation during action-execution and inhibition during action-observation. These findings suggest that multiple systems in humans may be endowed with neural mechanisms of mirroring for both the integration and differentiation of perceptual and motor aspects of actions performed by self and others.

Self-recognition has been demonstrated by a select number of primate species and is often used as an index of self-awareness. Whether a specialized neural mechanism for self-face recognition in humans exists remains unclear. We used event-related fMRI to investigate brain regions selectively activated by images of one's own face. Ten righthanded normal subjects viewed digital morphs between their own face and a gender-matched familiar other presented in a random sequence. Subjects were instructed to press a button with the right hand if the image looked like their own face, and another button if it looked like a familiar or scrambled face. Contrasting the trials in which images contain more bselfQ with those containing more familiar botherQ revealed signal changes in the right hemisphere (RH) including the inferior parietal lobule, inferior frontal gyrus, and inferior occipital gyrus. The opposite contrast revealed voxels with higher signal intensity for images of botherQ than for bselfQ in the medial prefrontal cortex and precuneus. Additional contrasts against baseline revealed that activity in the bselfQ minus botherQ contrasts represent signal increases compared to baseline (null events) in bselfQ trials, while activity in the botherQ minus bselfQ contrasts represent deactivations relative to baseline during bselfQ trials. Thus, a unique network involving frontoparietal structures described as part of the bmirror neuron systemQ in the RH underlies self-face recognition, while regions comprising the bdefault/resting stateQ network deactivate less for familiar others. We provide a model that reconciles these findings and previously published work to account for the modulations in these two networks previously implicated in social cognition. D 2004 Elsevier Inc. All rights reserved.

What are the neural correlates of insight solutions? To explore this question we asked participants to perform an anagram task while in the fMRI scanner. Previous research indicates that anagrams are unique in that they can yield both insight and search solutions in expert subjects. Using a single-trial fMRI paradigm, we utilized the anagram methodology to explore the neural correlates of insight versus search solutions. We used both reaction time measures and subjective reports to classify each trial as a search or insight solution. Data indicate that verbal insight solutions activate a distributed neural network that includes bilateral activation in the insula, the right prefrontal cortex, and the anterior cingulate. These areas are discussed with their possible role in evaluation and metacognition of insight solutions, as well as attention and monitoring during insight.