Visual Memory Research
The Genesis of Mnemonic Visual Systems 
Recurrent Dynamics in Excitable Media

Topic D9: Migraine Auras

 with observations of a novel  Counter-Flow Dynamic, 1990


      Descriptions of the scintillating spectra date back to Roman times.  In 2002, Bressloff and Cowan review the micro-anatomical dimensions and topology of the visual cortex.  Ohki, in 2000, describes "rows of clockwise and counter-clockwise pinwheel centers arranged alternately in a unique geometrical pattern." The migraine aura has features commending it as "A cellular model of excitable media including curvature and dispersion" as defined by Gerhardt M., 1990 . " Migraine phosphenes and the retino-cortical magnification factor "  ?    .Grüsser OJ.1995




       Subjectively, the apical angles of the migraine aura-chevrons appear to widen as the process spreads peripherally, suggesting the anisotropic domains of the neural template, (see C6) consistent with the known dimensions of receptive fields ... a Fibonacci series?  The domains so depicted appear broader circumferentially than in their radial measure; giving a flattening effect on the apical angles of a progressively-centrifugal chevron-display.  No diminution in their number is evident, though jittering is increasingly evident as the magnification progresses.
The uniform morphology of each visible chevron-element or texton is consistent with the known parameters of visual cortical neuro-architecture.
 
 Further Considerations of the visual  Migraine   Phenomena :


1) Triggers,  neuro-vascular , undetermined . 
2) Vascular components.
3) Spectral range.
4) Subjective morphology:  adjacent chevrons?  baseless triangles?  conjoined zig-zags?   
5) Anatomical dimensions and topology; rate of cortical spreading ~15 cm in 20 minutes.
6) Counter-rotating micro-elements, as seen March 14, 2001, 1.30 p.m.
7) Why macular sparing?  Why never a foveolar onset?  It is remarkable that the much emphasized
    spreading depression, which follows activation, is not initiated at fixation. 
8) Why no callosal transmissions?  (V1/V2  borders cross  the midline, Bressloff, 2002).
9) At eccentricity 15 degrees, no evidence seen  of a blind-spot-absence of the aura.