Even silent videos excite the listening brain
IS A sound only a sound if someone hears it? Apparently not. Silent videos that merely imply sound - such as of someone playing a musical instrument - still get processed by auditory regions of the brain.
Kaspar Meyer at the University of Southern California in Los Angeles and colleagues showed eight volunteers nine silent video clips that implied sound, including people playing violins, a dog howling and chainsaws cutting into trees. As they watched, their brains were scanned using functional MRI.
Each type of implied sound created a unique pattern of brain activity in the "early auditory cortices" - regions thought to be devoted to the initial processing of sounds. After noting these patterns in a several of the volunteers, the researchers were able to predict which type of video other volunteers had watched, just from the activity in the auditory cortices (Nature Neuroscience, DOI: 10.1038/nn.2533). The volunteers also reported imagining the sounds as they watched the videos.
The results broaden the role of regions previously thought only to be involved in initial sensory processing.
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