To recognise a famous voice, human brains use the same centre that is activated when the speaker’s face is presented, according to the results of an innovative neuroscience study which asked participants to identify US presidents.
The new study, published in the Journal of Neurophysiology, suggests that voice and face recognition are linked even more intimately than previously thought. It offers an intriguing possibility that visual and auditory information relevant to identifying someone feeds into a common brain centre, allowing for more robust, well-rounded recognition by integrating separate modes of sensation.
“From behavioural 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 never had a good explanation of why that happens,” said senior author Taylor Abel, MD, associate professor of neurological surgery at the University of Pittsburgh School of Medicine. “In the visual cortex, specifically in the part that typically processes faces, we also see electrical activity in response to famous people’s voices, highlighting how deeply the two systems are interlinked.”
Even though the interplay between the auditory and the visual brain processing systems has been widely acknowledged and investigated by various teams of neuroscientists all over the world, those systems were traditionally thought to be structurally and spatially distinct.
Few studies have attempted to directly measure activity from the brain centre – which primarily consolidates and processes visual information – to determine whether this centre is also engaged when participants are exposed to famous voice stimuli.
Researchers recruited epilepsy patients who had been implanted with electrodes measuring brain activity to determine the source of their seizures.
Abel and his team showed five 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 the electrical activity from the region of the brain responsible for processing visual cues (the fusiform gyri) showed that the same region became active when participants heard familiar voices, though that response was lower in magnitude and slightly delayed.
“This is important because it shows that auditory and visual areas interact very early when we identify people, and that they don’t work in isolation,” said Abel. “In addition to enriching our understanding of the basic functioning of the brain, our study explains the mechanisms behind disorders where voice or face recognition is compromised, such as in some dementias or related disorders.”
Source: University of Pittsburgh
