NYU/U. Rochester team find neurons in visual cortex adapt to images within .5 seconds ...( When you gaze out of a train the sce...),Health

When you gaze out of a train, the scenery appears to move even after the train has stopped. Vision researchers have generally dismissed this type of after-affect as a perceptual glitch that happens only after extended viewing of particular types of images. But now a team of NYU/U.Rochester neuroscientists have found that such after-affects may occur constantly and may be a critical part of normal visual perception.

The team found evidence that the viewing any image for as little as .5 seconds causes an after-affect. Furthermore, the researchers have hypothesized that these rapidly occurring after-affects -- or perceptual adaptations, as they're known -- play a critical role in helping the brain to rapidly discern subtle differences in visual patterns.

The researchers report their results in the August 27th issue of Science in an article entitled "Rapid Adaptation in Visual Cortex to the Structure of Images." They report that when they presented visual patterns for viewing, neuronal activity in the visual cortex dropped precipitously within .5 seconds, and the neurons remained desensitized to the image for several seconds thereafter. However, exposure to a second image (even one that was only subtly different from the first) caused a high level of neuronal activity.

James R. Müller -- who is the main author of the article -- said, "Our evidence suggests that visual adaptation -- which has often been regarded as on odd glitch -- may actually be critical to normal visual perception. Because adaptation occurs so rapidly, it can develop even during the fleeting stops our eyes make when we scan an image, and this can help us distinguish small differences between the things we see on successive stops."

Coauthor Peter Lennie said, "Neuroscientists have long know that that first stage of the visual cortex analyzes images to identify features in them, but we are constantly being surprised by the sophistication of this analysis. Our work provid
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Contact: Josh Plaut
josh.plaut@nyu.edu
212-998-6797
New York University
27-Aug-1999