Recent advances in brain-computer interfaces have made it possible to more accurately extract speech from neural signals in humans, but language is just one of the tools we use to communicate. âWhen my young nephew asks for ice cream before dinner and I say âno,â the meaning is entirely dictated by whether the word is punctuated with a smirk or a stern frown,â says Geena Ianni, a neuroscientist at the University of Pennsylvania. Thatâs why in the future, she thinks, neural prostheses meant for patients with a stroke or paralysis will decode facial gestures from brain signals in the same way they decode speech.
To lay a foundation for these future facial gesture decoders, Ianni and her colleagues designed an experiment to find out how neural circuitry responsible for making faces really works. âAlthough in recent years neuroscience got a good handle on how the brain perceives facial expressions, we know relatively little about how they are generated,â Ianni says. And it turned out that a surprisingly large part of what neuroscientists assumed about facial gestures was wrong.
The natural way
For a long time, neuroscientists thought facial gestures in primates stemmed from a neat division of labor in the brain. âCase reports of patients with brain lesions suggested some brain regions were responsible for certain types of emotional expressions while other regions were responsible for volitional movements like speech,â Ianni explains. Weâve developed a clearer picture of speech by tracing the origin of these movements down to the level of individual neurons. But weâve not done the same for facial expressions. To fill this gap, Ianni and her team designed a study using macaquesâsocial primates that share most of their complex facial musculature with humans.
This post highlights some fascinating developments in understanding macaque facial gestures and their connection to communication. It’s intriguing to see how technology like brain-computer interfaces is enhancing our insights into animal behavior. Exciting times for research in this field!
It’s indeed intriguing how these findings can enhance our understanding of non-human communication. Additionally, the connection to brain-computer interfaces opens up exciting possibilities for interpreting not just gestures, but potentially even emotions in other animals.