The Fortification Illusions of Migraines

Richards, Whitman

doi:10.1038/scientificamerican0571-88

Cited by 135 publications

(83 citation statements)

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“…Some have attributed the visual phenomena to primary visual cortex (32,33), because the visual image is oriented and highly retinotopic, and striate cortex is also retinotopic and selective for oriented stimuli (34)(35)(36)(37). However, human occipital cortex is comprised of multiple cortical areas, many of which (like V1) are also retinotopic (24)(25)(26)(37)(38)(39) and orientation-selective (e.g., ref.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of migraine aura revealed by functional MRI in human visual cortex

Hadjikhani

Río

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

1,328

999

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Cortical spreading depression (CSD) has been suggested to underlie migraine visual aura. However, it has been challenging to test this hypothesis in human cerebral cortex. Using high-field functional MRI with near-continuous recording during visual aura in three subjects, we observed blood oxygenation level-dependent (BOLD) signal changes that demonstrated at least eight characteristics of CSD, time-locked to percept͞onset of the aura. Initially, a focal increase in BOLD signal (possibly reflecting vasodilation), developed within extrastriate cortex (area V3A). This BOLD change progressed contiguously and slowly (3.5 ؎ 1.1 mm͞min) over occipital cortex, congruent with the retinotopy of the visual percept. Following the same retinotopic progression, the BOLD signal then diminished (possibly reflecting vasoconstriction after the initial vasodilation), as did the BOLD response to visual activation. During periods with no visual stimulation, but while the subject was experiencing scintillations, BOLD signal followed the retinotopic progression of the visual percept. These data strongly suggest that an electrophysiological event such as CSD generates the aura in human visual cortex.

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Section: Discussionmentioning

confidence: 99%

Mechanisms of migraine aura revealed by functional MRI in human visual cortex

Hadjikhani

Río

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

1,328

999

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“…Visual hallucinations appear in a great many syndromes: in auras preceding petit ma1 epilepsy [ll], in migraine [12], in insulin hypoglycaemia [13], hypnagogically [ 141, entoptically [15], photopically [ 161, and following the administering of hallucinogenic drugs [ 101. In this paper only those hallucinations seen in the earliest stages of drug-induced hallucinosis are discussed, although in fact they are seen under most of the other conditions as well.…”

Section: Visual Hallucinationsmentioning

confidence: 99%

Spontaneous symmetry breaking in large scale nervous activity

Cowan

1982

Int J of Quantum Chemistry

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A theory is outlined of the nature and origin of drug‐induced visual hallucination patterns. It is shown that such patterns correspond to blobs or stripes of visual neo‐cortical activity. A neuronal circuit is described that generates such patterns whenever its homogeneous resting state becomes unstable. Such a process is shown to be an example of spontaneous symmetry‐breaking, similar to that occurring in electro‐weak interactions, and in fluid convection. It is suggested that the neuronal instability is produced by the action of hallucinogens on monoamine secreting brain‐stem neurons.

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“…Associated with migraines is a well known phenomena called a scotoma which consists of a slowly moving blind region in the visual field. It has been suggested (Richards 1971) that this may be associated with cortical spreading depression (CSD) which is caused by the diffusion of large amounts of extracellular potassium (Leao, Bures et al 1974). (However, this point is controversial (Kranda and Kulikowski 1984).…”

Section: Two Spatial Dimensionsmentioning

confidence: 99%