Grasping the Intentions of Others with One’s Own Mirror Neuron System
Abstract: Understanding the intentions of others while watching their actions is a fundamental building block of social behavior. The neural and functional mechanisms underlying this ability are still poorly understood. To investigate these mechanisms we used functional magnetic resonance imaging. Twenty-three subjects watched three kinds of stimuli: grasping hand actions without a context, context only (scenes containing objects), and grasping hand actions performed in two different contexts. In the latter condition the context suggested the intention associated with the grasping action (either drinking or cleaning). Actions embedded in contexts, compared with the other two conditions, yielded a significant signal increase in the posterior part of the inferior frontal gyrus and the adjacent sector of the ventral premotor cortex where hand actions are represented. Thus, premotor mirror neuron areas, "areas active during the execution and the observation of an action," previously thought to be involved only in action recognition are actually also involved in understanding the intentions of others. To ascribe an intention is to infer a forthcoming new goal, and this is an operation that the motor system does automatically.

According to this study by UCLA neuroscientists, specialized brain cells called mirror neurons work in our understanding of others. These cells behave the same when one is performing an action as when they are observing another do it. To identify which areas of the brain are most active for a given task, the study used a brain imaging technique called functional magnetic resonance imaging (fMRI), to subtract the activation patterns from two different stimuli, thereby highlighting brain regions that are activated differentially in response to the difference in stimulus. Basically, fMRI (ephemerai uses a machine that scans the blood flow to functioning areas of the brain and pops out a picture, like this one from the aforementioned study:

The rest of Grasping the Intentions of Others with One’s Own Mirror Neuron System, PLoSBiology.org.