The facial feedback hypothesis suggests that our facial muscles don’t just express emotion—they help shape it.

When we smile or frown, those subtle movements feed back into the brain, reinforcing feelings of joy, sadness, anger, or calm.

A 2023 pilot study put this theory to the test using onabotulinumtoxinA (Botox®) to temporarily paralyze the glabellar “frown” muscles between the eyebrows.

Ten healthy women underwent brain scans (fMRI) before and after treatment while viewing emotional facial expressions.

After Botox, researchers observed increased brain activity in the left amygdala—a key region for emotion—and in the fusiform gyrus, which helps us recognize faces.

This was especially pronounced in response to happy expressions.

Interestingly, the women’s conscious ratings of the faces didn’t change, but their brains clearly registered something different.

As the authors explained, “preventing frowning through inhibition of glabellar muscle contraction altered amygdala processing for emotional faces.”

In short, paralyzing frown muscles changed how the brain processed emotion, even without the participants realizing it.

For those who regularly use Botox®, the findings raise an intriguing consideration: if facial movement shapes emotional processing, then long-term inhibition may subtly alter the way we feel and connect with others.

While more research is needed, those considering a break from Botox might find unexpected emotional clarity in the process.

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Adapted from: Stark, S, Stark, C, Wong, B, & Brin, MF. (2023). “Modulation of amygdala activity for emotional faces due to botulinum toxin type A injections that prevent frowning.” Scientific Reports, 13, 3333.