🗣️ Breathing to speak: when the brain takes control of breathing

Breathing is a vital action, so automatic that we forget about it. However, to produce speech, breathing must be modulated to synchronize exhalation with the rhythm of conversation.

In an article published in the journal Scientific Reports, scientists, using functional brain imaging, have identified the brain mechanisms that allow breathing to be synchronized with speech.

When breathing becomes language

To produce speech, our brain must transform this survival mechanism into a communication tool by modulating breathing to synchronize exhalation with the rhythm of conversation. A study published in Scientific Reports reveals how the central nervous system achieves this feat: it actively inhibits the brainstem, responsible for automatic breathing rhythm, to align breathing with speech production.

To explore this phenomenon, scientists studied natural conversations using functional magnetic resonance imaging (fMRI), while simultaneously recording breathing. Twenty-five volunteers, lying in a scanner, engaged in free, real-time dialogue with an interlocutor, while their brain activity and breathing were recorded synchronously.

This approach made it possible to distinguish cycles where breathing served only vital gas exchange from those where it was preparing to accompany speech.

A mechanism serving communication

The results show that approximately 200 milliseconds before starting to speak, participants had their lungs filled to prepare for vocal exhalation. At this precise moment, the brainstem, which generates the automatic breathing rhythm, is inhibited, making way for voluntary control.

This inhibition involves the sensorimotor cortex, which receives bodily information indicating that the lungs are ready to expel air for speaking, and the cerebellum, which finely coordinates the synchronization between exhalation and speech. This mechanism transforms an automatic act, intended for survival, into a voluntary act involved in communication.

This discovery provides unprecedented insight into the neurophysiological basis of human conversation. It shows that speaking is not just a linguistic or social act: it is also a biological act where the brain temporarily reorganizes a vital function. These results open perspectives for better understanding certain breathing disorders related to speech and could inspire new approaches for rehabilitation.