As knowledge of the human brain has deepened, our previous judgments and assumptions about morality, emotion, and empathy have been gradually replaced by an understanding of how emotion is an integral part of memory, learning, and cognition. In this context, mirror neurons provide support for the important role that emotion and empathy play in human development and neural functioning.

Developmental neuroscientists are researching how empathy and conscience are wired in the brain during childhood, including the role of “mirror neurons”. 

Mirror neurons not only broaden the understanding of how people learn through social cognition (including mimicry, imitation, interactive play and coordinated activity) but also how people interpret the intentions and feelings behind the actions, expressions, gestures, and experiences of others.

Like many advances in science, mirror neurons were discovered by accident. In the mid 1990s, Giacomo Rizzolatti, and his colleagues at the University of Parma were conducting research by mapping the specific firing patterns of neurons in the premotor cortex of macaque monkeys (the F5 region) while they performed specific tasks (i.e. grasping and reaching for a peanut or a banana) that corresponded to those brain areas. As they were reviewing the data, they noticed something that surprised them: the same specific neuronal pathways would fire when the monkey observed another monkey, or even a human perform the same task, even though the observing monkey was not moving at all.

This suggested that the observer has a direct link and experience of the actions that other individuals perform. Other research has shown that this link is not merely based on the observer’s ability to cognitively reflect on similar past experiences. For example, Andrew Meltzoff, a professor at University of Washington, discovered that by sticking your tongue out at a newborn, they would respond in kind. A newborn obviously has no cognitive context for this behavior.

But what is it that allows these neurons to respond when the observer witnesses an action? How are mirror neurons different from any other sort of neuron? The University of Parma scientists first identified specific mirror neurons by placing microelectrodes in the brains of the macaque monkeys during their experiments. The studies on macaque monkeys revealed that there were two kinds of visuomotor neurons in the F5 region of the premotor cortex: “canonical neurons” which activate when an object is recognized, and “mirror neurons” which activate when an action is performed or observed.

Cytological (cell) studies are being conducted in order to pinpoint the particular structure of mirror neurons. Our access to mirror neurons in humans is further obstructed by obvious ethical reasons regarding the use of microelectrodes deep in the brain. However, in comparable, and confirmatory studies on human brains (where individual electrodes have not been used), researchers have been able to observe the inferred activity of mirror neurons in different parts of the brain through the use of functional scans such as EEG, MEG, TMS, and fMRI.

In doing so, researchers have found that mirror neurons not only fire in the premotor cortex when observing others perform an action, but also in other emotionally pertinent areas of the brain, such as the insula, amygdala, anterior cingulate gyrus, and the ventromedial prefrontal cortex. The studies implicate the integration of interoception and emotion with mirror neurons in identifying the intentions and states of other observed acting agents.

In addition to cytological studies, current studies are seeking to identify the specific neural pathways of mirror neurons in humans. 

Studies on various disorders and brain damage, such as the autism spectrum, antisocial disorders, schizophrenia, and substance abuse have shed further light on the implications and scope of mirror neurons on empathic and cognitive functioning. Deficits in emotional cognition, which are related to these disorders, have been found to correlate with impaired mirror neuron function. In addition, the concentration of mirror neuron activity in Broca’s area suggests the role of integrating sensory input with meaning and language. Researchers are investigating the hypothesis that a lack of mirror neuron activity in individuals with autism could account for their difficulty in speech production, as well as their inability to grasp metaphorical (or cross sensory/interpretational) concepts. 

Mirror neurons are possibly an underlying mechanism of “theory of mind” (TOM), the (mainly) human capacity to recognize that other people are self-aware agents separate from ourselves, with their own feelings, experiences, and sense of reality.