March 27, 2023

Scientists speak of the facial feedback hypothesis “. Botox injections in the face, and especially in the forehead, might disrupt the way the brain processes and interprets the emotions of others, according to a new study published at the end of February 2023 in the journal Scientific Reports (Source 1).

The hypothesis is as follows: when we see someone expressing anger or joy on their face, we unconsciously contract certain muscles of our face to simulate the expression and thus better understand it. Consequently, the presence of botox might undermine this “ mirror effect and interfere with the understanding of other people’s emotions.

Here, a team of researchers from California investigated the facial feedback hypothesis with 10 female participants, ages 33 to 40, who volunteered to undergo a botox injection in the forehead. More specifically, the injection induced temporary paralysis of the glabella, this area located between the two eyebrows and whose muscle is responsible for frowning. The participants’ brain activity was then observed via functional MRI scans (fMRI), conducted once before infection and then two weeks following. During these fMRIs, participants viewed pictures of happy, sad, and neutral faces for comparison.

Verdict: the activity of the amygdala, a structure housed in the heart of the brain and responsible for processing emotions, was changed following botox injections. An alteration in the activity of the fusiform gyrus, part of the temporal cortex helping in the recognition of objects and faces, has also been observed.

For the authors of the study, these results confirm those of previous works which have shown a similar phenomenon. In 2011, a study even concluded that the injection of botox affected Emotional language processing: people undergoing this procedure at the glabella level took longer to read sentences that required frowning to convey the emotions of the text, than the other participants. A paradox when we see that some botox enthusiasts have a performing profession, which requires acting and transcribing emotions to the public.