Adaptation from invisible flicker

Shady, Sherif; MacLeod, Donald I. A.; Fisher, Heidi S.

doi:10.1073/pnas.0303452101

Cited by 102 publications

(84 citation statements)

References 23 publications

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“…For instance, it has been shown that adaptation by a grating with a spatial frequency too high to be resolved by the visual system can nevertheless reduce observers' sensitivity to a resolvable grating at the same orientation, relative to sensitivity at the orthogonal orientation (He and MacLeod, 2001). Similarly, stimuli with undetectable flicker frequencies can cause adaptation to flicker at detectable frequencies (Shady et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Masking by Inaudible Sounds and the Linearity of Temporal Summation

Plack¹,

Oxenham

Drga³

2006

J. Neurosci.

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Many natural sounds, including speech and animal vocalizations, involve rapid sequences that vary in spectrum and amplitude. Each sound within a sequence has the potential to affect the audibility of subsequent sounds in a process known as forward masking. Little is known about the neural mechanisms underlying forward masking, particularly in more realistic situations in which multiple sounds follow each other in rapid succession. A parsimonious hypothesis is that the effects of consecutive sounds combine linearly, so that the total masking effect is a simple sum of the contributions from the individual maskers. The experiment reported here tests a counterintuitive prediction of this linear-summation hypothesis, namely that a sound that itself is inaudible should, under certain circumstances, affect the audibility of subsequent sounds. The results show that, when two forward maskers are combined, the second of the two maskers can continue to produce substantial masking, even when it is completely masked by the first masker. Thus, inaudible sounds can affect the perception of subsequent sounds. A model incorporating instantaneous compression (reflecting the nonlinear response of the basilar membrane in the cochlea), followed by linear summation of the effects of the maskers, provides a good account of the data. Despite the presence of multiple sources of nonlinearity in the auditory system, masking effects by sequential sounds combine in a manner that is well captured by a time-invariant linear system.

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Section: Introductionmentioning

confidence: 99%

Masking by Inaudible Sounds and the Linearity of Temporal Summation

Plack¹,

Oxenham

Drga³

2006

J. Neurosci.

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“…A previous psychophysics study showed that flicker adaptation occurs from invisible luminance and chromatic flicker (13), and a functional magnetic resonance imaging (fMRI) study from our group found that the human brain responds to invisible chromatic flicker as far as visual area V4 (14), indicating that the invisible pattern information from chromatic flicker could be processed in retinotopic visual areas. Therefore, such stimuli allow us to ask whether, in the absence of awareness and related high-level cortex, invisible conflicting gratings can induce rivalry competition in the early visual cortex.…”

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confidence: 99%

Binocular rivalry from invisible patterns

Zou

Zhang

2016

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

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Binocular rivalry arises when incompatible images are presented to the two eyes. If the two eyes’ conflicting features are invisible, leading to identical perceptual interpretations, does rivalry competition still occur? Here we investigated whether binocular rivalry can be induced from conflicting but invisible spatial patterns. A chromatic grating counterphase flickering at 30 Hz appeared uniform, but produced significant tilt aftereffect and orientation-selective adaptation. The invisible pattern also generated significant BOLD activities in the early visual cortex, with minimal response in the parietal and frontal cortical areas. Compared with perceptually matched uniform stimuli, a monocularly presented invisible chromatic grating enhanced the rivalry competition with a low-contrast visible grating presented to the other eye. Furthermore, switching from a uniform field to a perceptually matched invisible chromatic grating produced interocular suppression at approximately 200 ms after onset of the invisible grating. Experiments using briefly presented monocular probes revealed evidence for sustained rivalry competition between two invisible gratings during continuous dichoptic presentations. These findings indicate that even without visible interocular conflict, and with minimal engagement of frontoparietal cortex and consciousness related top-down feedback, perceptually identical patterns with invisible conflict features produce rivalry competition in the early visual cortex.

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“…S1]. Because flicker within this frequency range is expected to be subliminal [the critical flicker fusion frequency is Ͻ50 Hz with luminance levels obtained on CRT monitors (18)(19)(20)], it is possible to test the AttentionGamma hypothesis psychophysically by examining whether subliminal flicker (that should evoke neural synchronization within this frequency band) triggers attentional orientation.…”

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confidence: 99%

Gamma flicker triggers attentional selection without awareness

Bauer

Cheadle

Parton

et al. 2009

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

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Gamma band modulations in neural activity have been proposed to mediate attentional processes. To support a causal link between gamma activity and attentional selection, we attempt to evoke gamma oscillations by a 50-Hz subliminal flicker. We find that a subliminal 50-Hz flicker at a target location, before target presentation, speeds up and enhances target detection and discrimination. This effect is specific to the middle of the gamma range because it is not evident at <35-Hz flicker. It requires 300 ms to build up, dissipates within 250 ms of flicker offset, and shows a tendency to invert after 500 ms. The results are discussed in relation to a role for gamma band neural synchrony in the allocation of visual attention.visual attention ͉ neural synchrony ͉ gamma ͉ psychophysics ͉ subliminal T he nature of the neural mechanisms underlying visual attention-the ability of humans and animals to select a limited number of stimuli from the multitude simultaneously present in the visual field for prioritized processing-remains a fundamental problem in visual neuroscience (1). A complete theory of visual attention must explain how the relative salience of selected stimuli is enhanced in neural terms, even though they are often not singled out by increased firing rates (2, 3). One recently proposed solution is the ''Attention-Gamma'' hypothesis, according to which synchronized gamma band (40-70 Hz) modulations in neural activity mediate attentional processes (4-10). This hypothesis is supported by a correlation, across trials, between the speed of behavioral responses in a visual detection task and the power in the gamma frequency range of V4 neurons (10-12). In these studies, Fries, Womelsdorf, and colleagues demonstrated that top-down visual attention is associated with internal gamma band synchrony in task-specific neural populations, which could be generated by top-down attentional modulations (13, 14). Thus, it is possible that selected neural representations are given a gamma band oscillatory tag by a top-down attention mechanism (15). If this is the case, it may be possible to trigger the effects of selective attention (enhanced selection and perception) by externally evoking gamma band oscillations of the relevant neural representation, thus mimicking the attentional tag.To test this hypothesis, we examined whether external stimulus flicker at a specific location, which is expected to evoke phaselocked neural activity at the same frequency, results in attentional orientation to that location in the absence of conscious detection of the flicker; if the flicker were detectable, it could lead to an orienting of attention toward its location as a result of exogenous or endogenous processes that are not specific to the temporal modulation. To test whether subliminally evoked neural synchronization has an attentional effect, we built on recent studies demonstrating that visual flicker in the midgamma band range (40-70 Hz) entrains periodic neural responses at the same frequency in the visual cortex [refs. 16 and 17; ...

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Adaptation from invisible flicker

Cited by 102 publications

References 23 publications

Masking by Inaudible Sounds and the Linearity of Temporal Summation

Masking by Inaudible Sounds and the Linearity of Temporal Summation

Binocular rivalry from invisible patterns

Gamma flicker triggers attentional selection without awareness

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