Scientists Identify Brain Region Where Individuals with Visual Impairments Recognize Faces through Sound

Sound-encoded faces activate left fusiform face area in early stages of vision

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Main summary

“Sound-encoded faces activate the left fusiform face area in early blind stages” – Plus one.

Using a specialized device that translates images into sound, neuroscientists and colleagues at Georgetown University Medical Center showed that blind people recognized basic faces using the part of the brain known as the fusiform face area, a region crucial for processing faces. in sighted people.

“It has been known for some time that blind people can compensate for their vision loss, to some extent, by using their other senses,” says Josef Rauschecker, Ph.D., D.Sc., professor in the department. of Neuroscience at Georgetown University and lead author of this study. “Our study tested to what extent this plasticity or trade-off exists between seeing and hearing by encoding basic visual patterns into auditory patterns with the help of a technical device that we refer to as a sensory substitution device. With the use of functional magnetic resonance imaging (fMRI ), we can determine where in the brain this compensatory plasticity is occurring.”

Face perception in humans and non-human primates is achieved by a mosaic of specialized cortical regions. How these regions develop remains controversial. Because of its importance for social behavior, many researchers believe that the neural mechanisms for facial recognition are innate in primates or depend on early visual experience with faces.

“Our results in blind people imply that the development of the fusiform area of ​​the face does not depend on experience with real visual faces but on exposure to the geometry of facial configurations, which can be transmitted through other sensory modalities,” adds Rauschecker.

Paula Plaza, Ph.D., one of the lead authors of the study, who is now at Universidad Andrés Bello, Chile, says;

“Our study demonstrates that the fusiform face area encodes the ‘concept’ of a face independently of the input channel or visual experience, which is an important finding.”

Six blind people and 10 sighted people, who served as control subjects, underwent three rounds of functional MRI scans to see which parts of the brain were activated during image-to-sound translation. The scientists found that brain activation by sound in blind people was mainly in the left fusiform area of ​​the face, while facial processing in sighted people occurred mainly in the right fusiform area of ​​the face.

“We think the left/right difference between blind and non-blind people may have to do with how the left and right sides of the fusiform area process faces, either as connected patterns or as separate parts, which may be an important clue. to help us perfect our sensory substitution device,” says Rauschecker, who is also co-director of the Center for Neuroengineering at Georgetown University.

Currently, with their device, blind people can recognize a basic “cartoon” face (such as a happy face emoji) when transcribed into sound patterns. Recognizing faces through sounds was a time-consuming process and many practice sessions. Each session began with getting people to recognize simple geometric shapes, such as horizontal and vertical lines; Then, the complexity of the stimuli gradually increased, so that the lines formed shapes, such as houses or faces, which then became even more complex (tall versus wide houses and happy faces versus sad faces).

Ultimately, the scientists would like to use images of real faces and houses in combination with their device, but the researchers note that they would first have to significantly increase the resolution of the device.

“We would love to find out if it is possible for blind people to learn to recognize people from their images. This may require a lot more practice with our device, but now that we have identified the region of the brain where the translation takes place, we will be able to know better how to adjust our processes,” concludes Rauschecker.

Authors

In addition to Rauschecker, the other Georgetown University authors are Laurent Renier and Stephanie Rosemann. Anne G. De Volder, who died while this manuscript was being prepared, was in the Neural Rehabilitation Laboratory of the Neuroscience Institute of the Catholic University of Louvain, Brussels, Belgium.

Study funding

This work was supported by a grant from the National Eye Institute (#R01 EY018923). The authors declare no personal financial interest related to the study.

Attribution/Source(s):

This peer-reviewed article related to our Visual Aids for People with Disabilities section was selected for publication by the editors of Disabled World because of its likely interest to readers in our disability community. Although content may have been edited for style, clarity, or length, the article “Scientists identify the region of the brain where visually impaired people recognize faces through sound” was originally written by Georgetown University Medical Center and published by Disabled-World.com on 11/22/2023 (Updated: 11/23/2023). If you require further information or clarification, you may contact Georgetown University Medical Center at georgetown.edu. Disabled World makes no warranties or representations in connection therewith.

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