Researchers have discovered neural circuits in the brains of rhesus macaque monkeys that could represent a common origin for social communication, including human speech.
The findings showed that these circuits are involved in face recognition, facial expression, and emotion and they may very well have given rise to our singular capacity for speech.
The team, from the Rockefeller University in New York City, used a novel experimental setup to take MRI scans of the brains of monkeys as they watched video clips of other monkeys making communicative facial expressions.
When the monkeys in the clips made a friendly lip-smacking gesture, the subject monkeys responded in kind — but only when their pre-recorded peers appeared to be making direct eye contact with them.
Besides, the face-perception regions of the monkeys’ brains that simply feed information to a region associated with emotion did not shuttle information to one another in straightforward, sequential fashion, said Winrich Freiwald, scientists at the varsity.
The videos that simulated social interaction through direct eye contact caused an unexpected third neural circuit to light up.
This suggests that specific areas of the animals’ brains are sensitive to social context, and perform the specialized cognitive functions necessary for social communication.
Generating a friendly lip smack, in particular, activated a region that resembles Broca’s area — a portion of the human brain concerned with the production of speech.