Visual illusions and travelling alpha waves produced by flicker at alpha frequency

Shevelev, I. A.; Kamenkovich, V. M.; Bark, E. D.; Verkhlutov, V. M.; Sharaev, G. A.; Михайлова, Е. С.

doi:10.1016/s0167-8760(00)00105-7

Cited by 37 publications

(33 citation statements)

References 26 publications

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“…Physiological correlates of the observed subjective experiences need to be further investigated, for example, by measures of electrophysiological activity allowing precise temporal registration of brain activations. Shevelev et al (2000) presented very interesting results showing that visual illusions (circle, spiral, and grid) may be the equivalent to alpha waves traveling across the cortex when the eyes are stimulated with flicker in the alpha frequency range.…”

Section: Discussionmentioning

confidence: 99%

Flicker-induced color and form: Interdependencies and relation to stimulation frequency and phase

Becker

Elliott

2006

Consciousness and Cognition

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Publication InformationBecker, C., & Elliott, M. A. (2006 AbstractOur understanding of human visual perception generally rests on the assumption that conscious visual states represent the interaction of spatial structures in the environment and our nervous system. This assumption is questioned by circumstances where conscious visual states can be triggered by external stimulation which is not primarily spatially defined. Here, subjective colors and forms are evoked by flickering light while the precise nature of those experiences varies over flicker frequency and phase. WhatÕs more, the occurrence of one subjective experience appears to be associated with the occurrence of others. While these data indicate that conscious visual experience may be evoked directly by particular variations in the flow of spatially unstructured light over time, it must be assumed that the systems responsible are essentially temporal in character and capable of representing a variety of visual forms and colors, coded in different frequencies or at different phases of the same processing rhythm.

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Section: Discussionmentioning

confidence: 99%

Flicker-induced color and form: Interdependencies and relation to stimulation frequency and phase

Becker

Elliott

2006

Consciousness and Cognition

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“…While there have been some electroencephalographic (EEG) studies of hallucinatory form (Shevelev, Kamenkovich, & Sharaev, 1996;Shevelev et al, 2000), the electrophysiological correlates of hallucinatory color have not yet been investigated. In most models, experience of hallucinatory color is attributed to early stages of visual processing (e.g.…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological correlates of flicker-induced color hallucinations

Becker

Gramann

Müller

et al. 2009

Consciousness and Cognition

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a b s t r a c tIn a recent study, Becker and Elliott [Becker, C., & Elliott, M. A. (2006). Flicker induced color and form: Interdependencies and relation to stimulation frequency and phase. Consciousness & Cognition, 15(1), described the appearance of subjective experiences of color and form induced by stimulation with intermittent light. While there have been electroencephalographic studies of similar hallucinatory forms, brain activity accompanying the appearance of hallucinatory colors was never measured. Using a priming procedure where observers were required to indicate the presence of one of eight target colors we compared electrophysiological correlates of hallucinatory color with brain states associated with other visual phenomena. Different target colors were accompanied by different patterns of EEG activation. However, in general, we found that the appearance of hallucinatory colors is preceded by a power decrease in the lower alpha band alongside an increase in gamma band frequencies. We argue that decreasing activity in the lower alpha band acts as a gating mechanism, inducing a switch in perception between different colors. The increasing gamma activation may correlate with the formation of a coherent conscious percept.

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“…The observed experiences were mostly simple geometric forms, which were classified into 20 categories, 12 of which were equivalent to the categories The optimal frequency to obtain these experiences was correlated (r = 0.86) with the dominant alpha-rhythm frequency with rings and spirals most frequently appearing at this frequency, and grids being related to frequencies 1 Hz below or above this individual dominant frequency. Shevelev et al [86] compared the generation of subjective experiences in this study where the stroboscopic stimulation was synchronized with the individual alpha frequency with a study without synchronization of flashes with Introduction the individual alpha rhythm [87]. Very interestingly, both stimulation regimes induced the same subjective experiences.…”

Section: Smythies Distinguished a Number Of Different Effects While Vmentioning

confidence: 96%

“…However, with synchronized presentation the subjective experiences appeared already 2 -5 seconds following stimulation onset, compared to 10 -15 seconds until subjective experiences developed in nonsynchronized stimulation. Registering the EEG activity on the scalp, Shevelev et al [86] observed typical trajectories of travelling EEG alpha-waves. This led them to argue that the observed subjective form experiences are a conscious experience of the spreading waves of activity scanning and reading information on the visual cortex.…”

Section: Smythies Distinguished a Number Of Different Effects While Vmentioning

confidence: 99%

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9. Johann Wolfgang von Goethe (1749–1832)

Dieckmann¹

1989

Reichthum Und Armut Deutscher Sprache

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Visual illusions and travelling alpha waves produced by flicker at alpha frequency

Cited by 37 publications

References 26 publications

Flicker-induced color and form: Interdependencies and relation to stimulation frequency and phase

Flicker-induced color and form: Interdependencies and relation to stimulation frequency and phase

Electrophysiological correlates of flicker-induced color hallucinations

9. Johann Wolfgang von Goethe (1749–1832)

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