We used to believe mirror neurons would transform medicine

Twenty years ago, mirror neurons were the future. In 2000, Dr. V.S. Ramachandran said, “Mirror neurons will do for psychology what DNA did for biology. They will provide a unifying framework and help explain a host of mental abilities…”

But as of 2020, none of this has occurred. We used to believe mirror neurons were going to change everything we knew — they were “the neurons that shaped civilization,” allegedly. What happened?

Monkey see, monkey understand

The excitement began in 1992, when researchers observed neurons, cells that send signals within the brain, discharging in two situations:

  • When you perform a motion action (i.e. grab an object)
  • When you see someone perform that same action (i.e. seeing you grab an object)

The neurons would fire the same regardless if you did the action or if you watched someone else do the action.

Why did this excite so many researchers? The implications were enormous. Scientists thought they discovered “empathy cells,” provoking the public and humanities scholars to make sweeping claims; in 2006, the New York Times described them as ‘’cells that read minds.”

We forgot how this momentum was mostly fueled by research conducted on macaque monkeys, not humans.

Cracks in the mirror

Humans do have mirror neuron systems; fMRI studies consistently show mirror neuron activity while performing, observing and imagining movement — but the implications for psychology are modest.

Evidence for mirror neuron activity in human empathy is still weak. According to a meta-analysis of 52 papers, there is still no firm correlation between empathy and mirror neuron activity; sample sizes are too small and methods are too inconsistent. How we know what someone else is thinking or feeling remains a mystery.

People on the autism spectrum often struggle with social interaction. This trope about autism encouraged neuroscientists like Ramachandran to argue that it comes from a dysfunctional mirror neuron system — a ”broken mirror” theory of autism.

The research didn’t pan out. Some in the autism community took issue with the framing of autism as a deficiency. A systemic review of 25 articles on autism and mirror neurons concluded, ”There is little evidence for a global dysfunction of the mirror system in autism,” arguing, ”It is time to move on from the broken mirror theory of autism.”

Speculative research

Despite facing this theoretical upheaval, mirror neurons also caused a gold rush of interdisciplinary peer-reviewed research letting us learn more about how the brain works, even if mirror neurons were not the breakthrough we thought they were. Such titles included:

  • “Activation of mirror-neuron system by erotic video clips…” (2008)
  • ‘’What goads cigarette smokers to smoke?…the mirror neuron system.’’ (2006)
  • ‘’…Connecting mirror neuron system and self-expansion model of love.’’ (2008)

According to UCLA neuroscientist Gregory Hickok, author of The Myth of Mirror Neurons, the number of papers annually published with “mirror neuron” in it doubled every two years — growing from four in the year 2000 to 135 in 2010. But what’s been the true effect of all this research?

Is it time to move on from mirror neurons? Despite numerous studies, book-length critiques and one failed theory, they still capture the imagination. Neuroscience still has a long way to go; we may not have seen the last of mirror neurons — whether they’re the next DNA or not.