[FRIAM] Visual Migraines

[Frank Wimberly]

Fascinating.  Thanks, Stephen.  That seems exactly on point.  I experience
number 3.

Incidentally, I appreciate your sympathy.  Fortunately, I experience no
pain with these hallucinations.

Frank

-----------------------------------
Frank Wimberly

My memoir:
https://www.amazon.com/author/frankwimberly

My scientific publications:
https://www.researchgate.net/profile/Frank_Wimberly2

Phone (505) 670-9918

On Mon, May 6, 2019, 3:44 PM Stephen Guerin <stephen.guerin at simtable.com>
wrote:

> 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
> <https://www.amazon.com/Fearful-Symmetry-Geometer-Dover-Mathematics/dp/0486477584>,
> and Peter Thomas <https://case.edu/math/thomas/>Case Western
>
> paper here: https://www.math.uh.edu/~dynamics/reprints/papers/nc.pdf.
> related paper here:
> https://royalsocietypublishing.org/doi/abs/10.1098/rstb.2000.0769
>
> What geometric visual hallucinations tell us about the visual cortex
> Paul C. Bressloff, Jack D. Cowan*, Martin Golubitsky, Peter J. Thomas and
> Matthew C. Wiener
>
> ABSTRACT:
> 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.com <stephen.guerin at simtable.com>
> CEO, Simtable  http://www.simtable.com
> 1600 Lena St #D1, Santa Fe, NM 87505
> office: (505)995-0206 mobile: (505)577-5828
> twitter: @simtable
>
>
> On 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 Wimberly
>>
>> My memoir:
>> https://www.amazon.com/author/frankwimberly
>>
>> My scientific publications:
>> https://www.researchgate.net/profile/Frank_Wimberly2
>>
>> Phone (505) 670-9918
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