Mirror, mirror, in the brain

As many parents like to advise, “Do as I say, not as I do.” This seems pretty simple, but the brain actually works directly against this expression — we are all wired to mimic what we observe. Mirror neurons are brain cells that fire in identical patterns when watching a behavior and performing that behavior. Essentially, when observing someone doing an action, our brains respond in the same way as when we do it ourselves. These parallel activity patterns play a critical role in observational learning, socialization and empathy, and behavioral development.

Mirror neurons were first discovered in a 1992 study by Giacomo Rizolatti and his team at the University of Parma. Rizolatti used electrodes to record firing patterns of individual neurons in monkeys and found corresponding activity during observation and motion. The monkeys observed movements, such as grasping and reaching, and then carried them out, and the same neurons activated during the two processes. These patterns of action shed light on the neurological mechanisms of observational learning and social cues.

“Babies learning to wave, dancers using physical mirrors to perfect their moves, and even movie-goers crying over a sad scene are all explained in part by the mirror neuron-related links between observation and experience.”

In a 2010 experiment, Roy Mukamel and his team followed up with the first observations of mirror neurons in humans. The researchers recorded extracellular activity while subjects observed and executed grasping actions and facial gestures. A significant number of neurons responded in both scenarios across the brain, particularly in the motor cortex, hippocampus, and frontal lobe. These brain regions control processes such as emotion and memory, movement and motor skills, judgement and reasoning, and decision-making. So, Mukamel’s findings suggest that many different sensory systems and pathways in the brain contain mirror neurons that integrate perception and action.

The “replay” function of mirror neurons is widely applicable across experiences. Hearing a song and singing the song activates these neurons, as does throwing a ball and watching someone throw it. Babies learning to wave, dancers using physical mirrors to perfect their moves, and even movie-goers crying over a sad scene are all explained in part by the mirror neuron-related links between observation and experience. These mirrored interactions are also involved in our ability to recognize and predict actions and activities in social situations.

During early childhood, observational learning is a primary method of behavioral development. Mirror neurons are part of the machinery behind a child’s ability to observe their parents and mimic how they talk and act. Language learning starts with imitation, so these neuron systems are thought to play a critical role in speech development. They also help develop behaviors such as walking, eating, playing, and socializing. Beyond childhood, mirror neurons could explain phenomena such as “contagious” yawning and laughter, and help with understanding conversational cues and social behaviors.

The discovery of mirror neurons and how they connect sensation and action has allowed scientists to explore their implications in healthcare, particularly in neurorehabilitation. Doctors have used “mirror therapy” for patients with strokes and other motor impairments, in which they attempt to regain motion in one limb by looking in a mirror at the functional counterpart to stimulate visual mirror neurons in the brain. It is also hypothesized that dysfunction of these pathways could explain some social disabilities such as autism spectrum disorder and sociopathy. These types of disorders are characterized by difficulty with social cues, imitation, and empathy — all processes related to the mirror neuron system.

The full functional range of mirror neurons is not yet established, and there is still much to explore about their developmental and clinical applications. Further research and advances in neuroimaging promise to provide deeper insights into the mirror neuron system, revealing more about the core of human development and behavioral learning.