Vision

Notes for Collection of Sand - essays by Italo Calvino

Collection of Sand is a collection of book reviews, exhibition reviews and travelogues that Italo Calvino wrote in the 70’s and 80’s. The quality varies. The best of them are unsurprisingly ekphrastic essays where Calvino described gardens, historical sites, and paintings in exquisite details. Those where he tried to regurgitate scientific or historical knowledge from academic books are less inspiring. But still, it is the variety of things that Calvino cared to write about that charms.
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How many photons get into your eyes?

A recent paper shows that our vision is so sensitive to light that human subjects can detect the presence of one single photon shot into their retinas. While scientists have been trying to establish the lower limit of visual sensitivity for a very long time, and it is generally accepted that a small number of photons are sufficient for detection since the 40’s, new advances in quantum optics finally allow us to manipulate light at single photon precision, and it is the first time that direct evidence for single photon sensitivity is demonstrated in a psychological experiment.
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The marmoset visual area DM for dummies

The visuotopic map of the marmoset dorsomedial visual cortex (area DM; see references) is sufficiently complex that it is probably worthwhile to design a few visual aides to make it more intuitive. The figure above is my first attempt. In this figure, DM is divided into three segments, with the most medial segment representing central upper visual field (nose and eye of Sir Isaac Newton), the middle segment representing the entire lower visual field, and the medial segment representing the peripheral upper visual field (the forehead and hair of Newton).
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The retinotopic map of marmoset V1

I created this figure to illustrate the retinotopic map of the primary visual cortex of the marmoset. The eccentricity contours are plotted in red, and polar angles are in blue. It’s very easy to create it in 3D so that you can rotate it around and see it from different angles. This is how you do it: Download ParaView, the open source 3D data visualization package.
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