Brain oscillations reveal that our senses do not experience the world continuously
(Medical Xpress) -- It has long been suspected that humans do not experience the world continuously, but rather in rapid snapshots.
Now, researchers at the University of Glasgow have demonstrated this is indeed the case. Just as the body goes through a 24-hour sleep-wake cycle controlled by a circadian clock, brain function undergoes such cyclic activity – albeit at a much faster rate.
Professor Gregor Thut of the Institute of Neuroscience and Psychology, said: “Rhythms are intrinsic to biological systems. The circadian rhythm, with its very slow periodicity of sleep and wake cycles every 24 hours has an obvious, periodic effect on bodily functions.
“Brain oscillations – the recurrent neural activity that we see in the brain – also show periodicity but cycle at much faster speeds. What we wanted to know was whether brain function was affected in a cyclic manner by these rapid oscillations.”
The researchers studied a prominent brain rhythm associated with visual cortex functioning that cycles at a rate of 10 times per second (10Hz).
They used a ‘simple trick’ to affect the oscillations of this rhythm which involved presenting a brief sound to ‘reset’ the oscillation.
Testing subsequent visual perception, by using transcranial magnetic stimulation of the visual cortex, revealed a cyclic pattern at the very rapid rate of brain oscillations, in time with the underlying brainwaves.
Prof Thut said: “Rhythmicity therefore is indeed omnipresent not only in brain activity but also brain function. For perception, this means that despite experiencing the world as a continuum, we do not sample our world continuously but in discrete snapshots determined by the cycles of brain rhythms.”
The research, ‘Sounds reset rhythms of visual cortex and corresponding human visual perception’ is published in the journal Current Biology.
More information: Romei et al., Sounds Reset Rhythms of Visual Cortex and Corresponding Human Visual Perception, Current Biology (2012), doi:10.1016/j.cub.2012.03.025
Journal reference:
Current Biology
Provided by
University of Glasgow
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Explains why we roughly need 20 images per second to see movies instead of a series of stills (Nyquist-Shannon sampling theorem). I bet this could be used to further increase the efficiency of compression algorithms that are based on psychological effects (such as mp3 which is based on psychoacoustics).
May 14, 2012
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May 14, 2012
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I heard somewhere that cinemas are upping the standard framerate from 24 to 48 fps because these 3D films are known to give people headaches, seems a bit overkill and they should consider tuning the frame rate to our visual cortex rhythm, assuming they are the same for everyone, otherwise the person viewing would need some occipital transcranial magnetic stimulation first and have algorhythms compress the video based on information gained from an individuals brain.
May 14, 2012
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Use this site and see for yourself:
http://boallen.co...are.html
May 14, 2012
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May 14, 2012
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Film is an exposure, that captures blurring of motion. When it is filmed, it captures the scene X times a second, but motion during that will blur across each frame. In a digital medium, each frame is purely static, no motion blurring, so differences in position between frames is much easier to perceive.
May 14, 2012
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(To fill gaps that exist...or not.)
May 14, 2012
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After all, computers and cameras all capture things a frame at a time.
The metaphyical reason is that it is the simplest way to preserve causality. If different parts of perception were not discretely linked and processed with a specific point of time, then it would be much more difficult to be a living human...we would have an even harder time making true connections between things in the physical world.
For example, have you ever seen a corrupted or badly coded youtube video where the motion updates while the color does not? You might see a figure walking around, yet he has the image/pattern of a ladder on a wall...
May 14, 2012
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so something or someone could be in the room with me and i would never see it?
i wonder what those black dots are that go zipping away from the corner of the room when i turn my head to look?
no, not the protein shadows floating on my corneas, the other things...
May 16, 2012
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Seriously though, pretty much every aspect of cortical operation is cyclical. If you think about it this must be so because the different ingredients of perceptual quality and information content are mediated in different cortical areas which must mutually and reciprocally stimulate each other in order to create and maintain a networking event that properly represents/embodies the experience.
The most succinct explanation of consciousness you will come across is that C. is what it is like to be the process of updating of the model of self in the world within your brain. This model is a navigational device that allows us to locate ourselves within our physical and social environment.
May 19, 2012
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May 20, 2012
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May 20, 2012
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