Inject a tiny amount of a lethal toxin into your wrinkles and you won't just get a frozen face that can't express emotions — you might just deaden your ability to feel those emotions in the first place. LiveScience reports that the effect of Botox on the muscles could interfere with brain activity as well.

The reason might just surprise you (if you can move your eyebrows, that is). Scientists believe that facial expressions are linked to emotional experiences.

"With Botox, a person can respond otherwise normally to an emotional event, [such as] a sad movie scene, but will have less movement in the facial muscles that have been injected, and therefore less feedback to the brain about such facial expressivity," researcher Joshua Davis of Barnard College in New York told LiveScience.

"It thus allows for a test of whether facial expressions and the sensory feedback from them to the brain can influence our emotions," he said.

Davis and his research team did just that, showing emotionally charged videos to subjects both before and after injecting them with either Botox, made from the muscle-relaxing botulinum toxin, or Restylane. The latter substance was used as a control because it adds filler to wrinkles or lips, making them fuller, but it doesn't limit muscle movement.

According to a research paper published by the team in June's issue of the journal Emotion, the Botox group "exhibited an overall significant decrease in the strength of emotional experience” compared to the control group.

But these results don't just apply to Botox users. The simple act of smiling when you're feeling down could actually result in a happier mood, the researchers note.