Cosmetic use of botulinum toxin-a affects processing of emotional language

Abstract

How does language reliably evoke emotion, as it does when people read a favorite novel or listen to a skilled orator? Recent evidence suggests that comprehension involves a mental simulation of sentence content that calls on the same neural systems used in literal action, perception, and emotion. In this study, we demonstrated that involuntary facial expression plays a causal role in the processing of emotional language. Subcutaneous injections of botulinum toxin-A (BTX) were used to temporarily paralyze the facial muscle used in frowning. We found that BTX selectively slowed the reading of sentences that described situations that normally require the paralyzed muscle for expressing the emotions evoked by the sentences. This finding demonstrates that peripheral feedback plays a role in language processing, supports facial-feedback theories of emotional cognition, and raises questions about the effects of BTX on cognition and emotional reactivity. We account for the role of facial feedback in language processing by considering neurophysiological mechanisms and reinforcement-learning theory.

Figures

Fig. 1

Emotional sentence (angry, sad, and happy) reading times (in Milliseconds) before (1st session) and after (2nd session) BTX injection in corrugator muscle. Error bars indicate +/- 1 s.e.m. Significant comparisons are indicated with an asterisk.

Fig. 2

Emotional sentence (angry, sad, and happy) residual reading times (controlling for sentence length, in milliseconds) before (1st session) and after (2nd session) BTX injection in corrugator muscle. Error bars indicate +/- 1 s.e.m. Significant comparisons are indicated with an asterisk.