[FRIAM] Visual Migraines

[Jochen Fromm]

I guess Stu means Stuart Kauffman? He is 79 years old already but has written another book about the emergence and evolution of life called "A world beyond physics"https://global.oup.com/academic/product/a-world-beyond-physics-9780190871338?cc=de&lang=enNot sure if this fits to the subject "Visual Migraines" :-/ Get well soon Frank.-Jochen
-------- Original message --------From: Stephen Guerin <stephen.guerin at simtable.com> Date: 5/6/19  23:43  (GMT+01:00) To: The Friday Morning Applied Complexity Coffee Group <friam at redfish.com> Subject: Re: [FRIAM] Visual Migraines Frank,Sorry you're experiencing migraines - no fun! On the upside, the mathematician in you may appreciate the opportunity of direct observation of potentially interesting feedback phenomena.Jack Cowan, one of Stu's mentors, gave a nice talk at BioGroups back in 2001 on geometric patterns during hallucination due to instabilities driving the feedback structures of the visual cortex. Jack had a couple papers paper was with Paul Bressloff. Utah Math Department (https://www.math.utah.edu/~bresslof/) Marty Golubitsky, co-author with Ian Stewart of Fearful Symmetry, and Peter Thomas Case Westernpaper here: https://www.math.uh.edu/~dynamics/reprints/papers/nc.pdf. related paper here: https://royalsocietypublishing.org/doi/abs/10.1098/rstb.2000.0769What geometric visual hallucinations tell us about the visual cortexPaul C. Bressloff, Jack D. Cowan*, Martin Golubitsky, Peter J. Thomas and Matthew C. WienerABSTRACT: Geometric visual hallucinations are seen by many observers after taking hal- lucinogens such as LSD, cannabis, mescaline or psilocybin, on viewing bright flickering lights, on waking up or falling asleep, in “near death” experiences, and in many other syndromes. Klu ̈ver organized the images into four groups called “form constants”: (1) tunnels and funnels, (2) spirals, (3) lattices, including honeycombs and triangles, and (4) cobwebs. In general the images do not move with the eyes. We interpret this to mean that they are generated in the brain. Here we present a theory of their origin in visual cortex (area V1), based on the assumption that the form of the retino-cortical map and the architecture of V1 determine their geometry. We model V1 as the continuum limit of a lattice of interconnected hypercolumns, each of which itself comprises a number of interconnected iso-orientation columns. Based on anatomical evidence we assume that the lateral connectivity between hypercolumns exhibits symmetries rendering it invariant under the action of the Euclidean group E(2), composed of reflections and translations in the plane, and a (novel) shift–twist action. Using this symmetry, we show that the various patterns of activity that spontaneously emerge when V1’s spatially uniform resting state becomes unstable, correspond to the form constants when transformed to the visual field using the retino–cortical map. The results are sensitive to the detailed specification of the lateral connectivity and suggest that the cortical mechanisms which generate geometric visual hallucinations are closely related to those used to process edges, contours, textures and surfaces._______________________________________________________________________Stephen.Guerin at Simtable.comCEO, Simtable  http://www.simtable.com1600 Lena St #D1, Santa Fe, NM 87505office: (505)995-0206 mobile: (505)577-5828twitter: @simtableOn Mon, May 6, 2019 at 1:39 PM Frank Wimberly <wimberly3 at gmail.com> wrote:Also called optical migraines.  I experience them as perfect, complex, geometric patterns which scintillate and exhibit various colors.  How does that come about from the glop that is my brain or retina or whatever?  It's all glop.Frank-----------------------------------Frank WimberlyMy memoir:https://www.amazon.com/author/frankwimberlyMy scientific publications:https://www.researchgate.net/profile/Frank_Wimberly2Phone (505) 670-9918
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