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This is how Deaf people’s brains process visual rhythms

waves

The brain has a remarkable ability to respond to change – to the extent of reorganizing itself after a traumatic injury or a sensory disability, as well as enabling the nervous system to adjust to the loss of an entire set of sensory inputs.

Evidence that brain circuits can be ‘re-purposed’ was recently reported in a study published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Researchers found that Deaf people had the same auditory processing regions in their brains activated when they interpreted visual rhythms from a flashing light, as when normal hearing people listened to the rhythms. 

How was the study carried out?

Researchers used functional MRI scans to take brain scans of both Deaf and hearing subjects under various test conditions.

What was tested?

All subjects were asked to discriminate between different rhythms of flashing lights.

Hearing subjects were also asked to listen to, and discriminate between, different rhythms, which were played to them.

Findings

As anticipated, in the flashing light test the brain scans of the hearing subjects showed activity in the visual processing system. Scans taken during the audible version of the task showed that the auditory cortex was activated.

However, in the Deaf subjects, the brain scans showed that the auditory cortex was activated when looking at rhythmic patterns of flashing lights (as were parts of the visual processing system).

Conclusions

The Deaf subjects’ neural responses to the visual rhythmic stimuli closely matched the hearing subjects’ neural responses to the auditory stimuli, with both groups brains showing reactions in their auditory cortexes. 

Why is this important?

“These findings are important because though we know the brain is capable of reorganizing itself, we don’t know what principles govern this reorganization,” according to Ars Technica Science Correspondent, Roheeni Saxena.

“Here, the authors demonstrate that the exact same regions that allow hearing people to interpret auditory rhythms are used by deaf people to interpret visual rhythms. This suggests that the rewiring of the brain may directly map similar tasks to specific functional units in the brain. Though more research is needed, this study adds to our overall understanding of neural rewiring.”

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Angie Aspinall
Phonak hEARo, Angie is a freelance journalist, copywriter, website designer and social media consultant. (www.aspinallink.co.uk) She lives in Scotland with her husband Richard, and their Westie, Tilly. Angie was diagnosed with Otosclerosis in her right ear at the age of 30. In 2011, she suffered sudden profound hearing loss in her left ear. She now uses a Phonak CROS II with a Phonak Audéo V hearing aid. You can follow Angie's international discussion group #HearingLossHour on Twitter @hearinglosshour.

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