"""
"""
centre of the human retina [...] bipolar cell often receives its central input from just one photoreceptor, and its surrounding input from a couple more. In contrast, a bipolar cell in the more peripheral regions of the retina might collect signals from 25 photoreceptors before joining signals with 5000 other bipolar cells when communicating with the retinal ganglion cell (which, in turn, transmits information to the brain). This means that a single retinal ganglion cell in the periphery of our retina collects information from up to 75,000 photoreceptors! This allows it to keep watch over a much larger area of the visual world than cells that pool information from a much smaller number of receptors (hence, cells in the periphery are said to have large receptive fields). A further perk of such great convergence is that these cells are exquisitely sensitive to light, since they can add up weak signals from thousands of receptors. This is primarily why astronomers have historically preferred to look for faint stars by directing the telescope just slightly off-centre of their retinas – a technique known as averted vision.
[...]
larger receptive fields, they become less capable of resolving small details. Thus, the brain is unlikely to be informed of the presence of small objects in the visual periphery – something that is responsible for the fact that the dots you see in the extinction illusion are never far away from the centre of your gaze.
[...]
if another dot were to occur in the vicinity of the first one (below), there is a high probability that it would also stimulate the same receptive field’s centre. [...] In the case of these two dots, the visual brain is receiving the same signal from the same retinal ganglion cell. This means that the information it has access to does not allow it to reasonably infer where something might be happening in a particular area of the visual world. Thus, as receptive fields of neurons in the retina grow larger, their signals give the brain less and less certainty as to what exactly is happening and where. When such certainty about visual events is lacking, there is no reason for them to arise in our conscious experience. Instead, the brain appears to provide us with an experiential ‘filler’ (you don’t exactly go around seeing ‘uncertainty’) and some level of ignorance regarding just how poor our spatial vision is in the eye’s periphery.
"""
https://theneurosphere.com/2016/09/17/the-basic-neurobiology-behind-the-visual-illusion-that-is-here-to-break-the-internet/
https://theneurosphere.com/2016/09/17/the-basic-neurobiology-behind-the-visual-illusion-that-is-here-to-break-the-internet

Labels: Oleg Zabluda

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