What is a considerable brain

Conscious brain activity is not so easily distracted

Perception from the corner of the eye, a movement on the edge of the field of vision, seemingly insignificant details: we perceive numerous things without them attracting our conscious attention. However, what makes the difference between conscious and unconscious information processing in the brain is largely unclear. Neuroscientists at the University of Tübingen have now come one step closer to enlightenment. Their results have now been published in the journal “Current Biology”.

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Usually both eyes see the same picture. When different images are shown to the eyes, a visual illusion is created known as "binocular rivalry". Then the brain cannot decide between the alternatives, and our perception alternates between the one and the other image over a period of several seconds. The two images are then “rivals” in access to consciousness. Natalia Zaretskaya and Andreas Bartels from the Center for Integrative Neurosciences at the University of Tübingen use this rivalry in their investigations.

Unexpected result between static and moving image

The scientists analyzed the change in perception between a moving visual stimulus and a static image of the test participants. They showed one eye of the test subjects a still picture, and at the same time a moving one to the other eye. They measured the time how long the brain consciously gave attention to each image. They also use magnetic impulses to specifically disrupt the processes in a brain region that is specifically responsible for processing visual movement.

The result: while the brain unconsciously processed the moving stimulus, the interference impulses in the moving area prevented this stimulus from reaching consciousness. In contrast, the disruptive magnetic impulses had no effect, while the moving stimulus was consciously processed.

A movement that remains unconscious can easily be disrupted in its neural processing. She has difficulty gaining the upper hand in competition against a rival image. But as soon as the movement stimulus reaches consciousness, its processing is evidently more resistant to external disturbances.

Conscious and unconscious perception differ considerably

"This result shows that there is a considerable difference between conscious and unconscious movement processing in the brain," says Andreas Bartels. A property of conscious neuronal processing therefore seems to be a more stable and less susceptible to interference representation of the stimuli. The next question the scientists want to answer is how this neural stability is achieved.

(Current Biology, 3013; doi: 10.1016 / j.cub.2013.09.002)

(Eberhard Karls University of Tübingen, October 23, 2013 - AKR)

October 23, 2013