Our brains determine what our eyes see

November 21st, 2007 - 1:13 pm ICT by admin  

Washington, Nov 21(ANI): When presented with an optical illusion, the image that people see depends entirely on changes that occur in our brain, a new study has found.

These images, once formed, do not change.

The study, led by John Serences, a UC Irvine cognitive neuroscientist, and co-author Geoffrey Boynton, associate professor at the University of Washington, found that when viewing ambiguous images such as optical illusions, patterns of neural activity within specific brain regions systematically change as perception changes.

For the study, the team used functional Magnetic Resonance Imaging (fMRI) to measure patterns of neural activity in the middle temporal (MT) region of the brain, an area associated with motion perception, under two different scenarios.

In the first, participants were asked to view objects moving only in one direction and to identify the direction in which the objects were moving, i.e. left or right.

The volunteers were then presented with objects in which the direction of motion was ambiguous, or undefined, and they were asked to identify the main direction of motion.

The analysis of the study found that the pattern of neural activity in the MT region was highly similar when an observer viewed real motion moving to the left and when they thought they saw the ambiguously moving objects moving to the left.

The close correspondence between the pattern of activation in MT and what the observer reports seeing suggests that this region of your brain plays an important role in generating conscious experience of the world around you, Serences said.

In the study, the scientists also found that patterns of neural activity in some brain regions were very similar when observers were presented with comparable ambiguous and unambiguous images.

The fact that some brain areas show the same pattern of activity when we view a real image and when we interpret an ambiguous image in the same way implicates these regions in creating the conscious experience of the object that is being viewed, Serences said.

The study is published in the Journal of Neuroscience. (ANI)

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