New research suggests the brain's visual cortex processes audio information as well.
Auditory input could allow the visual system to predict incoming data in a "survival response," a University of Glasgow news release reported.
"Sounds create visual imagery, mental images, and automatic projections," Professor Lars Muckli, of the Institute of Neuroscience and Psychology at the University of Glasgow, said in the news release. "So, for example, if you are in a street and you hear the sound of an approaching motorbike, you expect to see a motorbike coming around the corner. If it turned out to be a horse, you'd be very surprised."
Researchers looked at the functioning visual cortex in 10 study participants using functional Magnetic Resonance Imaging (fMRI).
In one experiment they asked blindfolded participants to listen to sounds of traffic, birdsongs, and a crowd of people. They used a special algorithm to determine if the information was being processed in the visual cortex.
Another experiment found that imagined images without any visual or auditory stimuli evoked activate in the visual cortex.
"This research enhances our basic understanding of how interconnected different regions of the brain are. The early visual cortex hasn't previously been known to process auditory information, and while there is some anatomical evidence of interconnectedness in monkeys, our study is the first to clearly show a relationship in humans," Muckli said. "In [the] future we will test how this auditory information supports visual processing, but the assumption is it provides predictions to help the visual system to focus on surprising events which would confer a survival advantage."
The research could help lead to breakthroughs in the understanding of conditions such as schizophrenia or autism. The findings could help show how sensory perceptions differ in people suffering from these conditions.
In the future the team will look at additional sounds in hopes of determining how precise predictive coding in the brain really is.
