To identify a voice, the brain relies on sight

To recognize a famous voice, the human brain uses the same center that lights up when the speaker’s face is presented, according to a clever neuroscience study where participants were asked to identify US presidents.

The new study, published last week in the Journal of Neurophysiology, suggests that voice and facial recognition are even more intimately linked than previously thought. It offers an intriguing possibility that visual and auditory information relevant to identifying someone feeds into a common brain center, enabling more robust and complete recognition by integrating separate modes of sensation.

“From behavioral research, we know that people can identify a familiar voice faster and more accurately when they can associate it with the speaker’s face, but we’ve never had a good explanation of why this is happening,” said lead author Taylor Abel, MD, associate. professor of neurological surgery at the University of Pittsburgh School of Medicine. “In the visual cortex, particularly in the part that typically processes faces, we also see electrical activity in response to the voices of famous people, highlighting how closely the two systems are intertwined.”

Even though the interplay between auditory and visual brain processing systems has been widely recognized and studied by various teams of neuroscientists around the world, these systems have traditionally been considered structurally and spatially distinct.

Until recently, few studies attempted to directly measure the activity of the brain center – whose primary role is to consolidate and process visual information – to determine whether this center is also engaged when participants are exposed to stimuli. famous vocals.

The Pitt researchers had a unique opportunity to study this interaction in epilepsy patients who, as part of their medical care, were temporarily implanted with electrodes that measured brain activity to determine the source of their seizures.

Five adult patients agreed to participate in the study, where Abel and his team showed participants photographs of three US presidents – Bill Clinton, George W. Bush and Barack Obama – or played short recordings of their voices, and asked participants to identify them. .

Recordings of electrical activity from the region of the brain responsible for processing visual signals – called the fusiform gyri, or FG – showed that the same region became active when participants heard familiar voices, although this response was weaker. and slightly delayed. .

“This is important because it shows that the auditory and visual areas interact very early on when we identify people, and they don’t operate in isolation,” Abel said. “In addition to enriching our understanding of basic brain functioning, our study explains the mechanisms underlying disorders where voice or face recognition is compromised, such as in certain dementias or related disorders.”

Ariane Rhone, Ph.D., of the University of Iowa, and Kyle Rupp, Ph.D., of Pitt, are co-first authors. The study’s other authors are Dan Tranel, Ph.D., and Matthew Howard, III, Ph.D., both of the University of Iowa; and Jasmine Hect, Ph.D., and Emily Harford, Ph.D., both of Pitt.

This work was supported by National Institutes of Health grants R01 DC004290 and R21 DC019217.

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