Social interactions can elicit a wide range of emotions. One of the most important components to have in interpersonal relationships is empathy — the ability to understand and feel what another person is experiencing. Humans are dynamic social animals, and the ability to mirror others emotions is neurologically embedded into our brain.

Mirror neurons were first discovered in the 1980s while experimenting with monkeys. Motor neurons fire when you do something, and during the study, researchers found that a primate's neurons for action or movement were also actively set off simply by just looking at another monkey doing something. In a literal sense — monkey see, monkey do.

There are a lot of interesting implications to this fact, and scientists are still researching how this works with people.

Mirror neurons might be crucial to fundamental components of our speech, interaction, and empathy, and their lack may also influence autism. If mirror neurons are at play for dynamic human interactions, it might bring a whole new meaning to the saying "smile, and the world smiles with you."

Mirror neurons activate when you smile 

Scientists have looked at areas of the brain that are activated when somebody else smiles. Using fMRI brain imaging, scientists found that the standard areas of visual perception lit up. But they also found that other interesting areas of the brain lit up as well.

"The results show that perceiving and expressing pleasant facial affect share a common neural basis in areas concerned with motor as well as somato- and limbic-sensory processing," the researchers write.

In other words, in the premotor cortex, our muscles for forming a smile were activated. Our brain activity fired off in both the physical and emotional state of smiling, which shows that when someone smiles, our mirror neurons simulate our own state of smiling.This may show that simulation in our mind may contribute to helping us understand what another person is feeling.

There seems to be a unique psychological and physiological interplay relationship here as well. An experimental study in 2007 had subjects view photographs of people's faces and asked them to evaluate their expressions. During some of the trials, the participants had to bite down on a pen while viewing the photos. It was found that when biting down, which limited the facial muscles from moving and stopped them from smiling, the participants were less likely to recognize happy expressions in the photographs.

What we can garner from this is that the inability to smile brought about an empathetic lapse in recognizing another person's happiness.

Smiling can lift your mood

When we smile or see another person smile, we mentally simulate that action and feel happier. Just the simple act of smiling triggers a rush of positive neurological activity. You can count on lowering stress and having a new, uplifted mood.

Smiles usually stem from happiness. But it turns out, the opposite is true as well. The act of smiling can boost our dopamine and increase our feeling of happiness.

Neurologist Dr. Isha Gupta confirms that smiling sparks a chemical change in the brain. She states, "Dopamine increases our feelings of happiness. Serotonin release is associated with reduced stress. Low levels of serotonin are associated with depression and aggression."

On a surface level, we're more prone to reciprocate what we see around ourselves and mirror that internally. The reduction of mirror neuron activity may contribute to autism, as those with the condition are often unable to interact socially.

Autism and mirror neurons

In 2006, neuroscientist Marco Iacoboni published a paper in Nature Neuroscience linking mirror neuron dysfunction to autism. His research found that mirror neurons are not only an important element of social cognition, but defects in them may underlie a number of mental disorders.

In an interview with Scientific American, Iacoboni explained that

"Reduced mirror neuron activity obviously weakens the ability of these patients to experience immediately and effortlessly what other people are experiencing, thus making social interactions particularly difficult for these patients. Patients with autism have also often motor problems and language problems. It turns out that a deficit in mirror neurons can in principle explain also these other major symptoms."

The majority of people without mirror neuron dysfunction seamlessly understand social cues and empathetically experience a feeling without thought.

"When I see you smiling, my mirror neurons for smiling fire up, too, initiating a cascade of neural activity that evokes the feeling we typically associate with a smile. I don't need to make any inference on what you are feeling, I experience immediately and effortlessly (in a milder form, of course) what you are experiencing," Iacoboni states.

Mirror neurons are the only types of brain cells known to code the actions of others in tandem with activating our own. They hold a special importance in social interactions.

While we'll never be able to truly feel what it's like to be someone else, our mirror neuron system gives us the ability to mentally simulate another person's actions fluidly.

A smile goes a long way after all.