scholarly journals Reduced alpha amplitudes predict perceptual suppression

2020 ◽  
Author(s):  
Eva Poland ◽  
Aishwarya Bhonsle ◽  
Iris Steinmann ◽  
Melanie Wilke
Keyword(s):  
Visual Awareness ◽  
Occipital Cortex ◽  
Threshold Level ◽  
Stimulus Onset ◽  
Alpha Activity ◽  
Motion Onset ◽  
Full Field ◽  
Motion Stimulus ◽  
The Individual ◽  
Target Visibility

Abstract The amplitude of prestimulus alpha oscillations over parieto-occipital cortex has been shown to predict visual detection of masked and threshold-level stimuli. Whether alpha activity similarly predicts target visibility in perceptual suppression paradigms, another type of illusion commonly used to investigate visual awareness, is presently unclear. Here, we examined prestimulus alpha activity in the electroencephalogram (EEG) of healthy participants in the context of a generalized flash suppression (GFS) task during which salient target stimuli are rendered subjectively invisible in a subset of trials following the onset of a full-field motion stimulus. Unlike for masking or threshold paradigms, alpha (8-12 Hz) amplitude prior to motion onset was significantly higher when targets remained subjectively visible compared to trials during which the targets became perceptually suppressed. Furthermore, individual prestimulus alpha amplitudes strongly correlated with the individual trial-to-trial variability quenching following motion stimulus onset, indicating that variability quenching in visual cortex is closely linked to prestimulus alpha activity. We conclude that predictive correlates of conscious perception derived from perceptual suppression paradigms differ substantially from those of obtained with “near threshold paradigms”, possibly reflecting the effectiveness of the suppressor stimulus.

scholarly journals Reduced alpha amplitudes predict perceptual suppression

2020 ◽  
Author(s):  
Eva Poland ◽  
Aishwarya Bhonsle ◽  
Iris Steinmann ◽  
Melanie Wilke
Keyword(s):  
Visual Awareness ◽  
Occipital Cortex ◽  
Threshold Level ◽  
Stimulus Onset ◽  
Alpha Activity ◽  
Motion Onset ◽  
Full Field ◽  
Motion Stimulus ◽  
The Individual ◽  
Target Visibility

ABSTRACTThe amplitude of prestimulus alpha oscillations over parieto-occipital cortex has been shown to predict visual detection of masked and threshold-level stimuli. Whether alpha activity similarly predicts target visibility in perceptual suppression paradigms, another type of illusion commonly used to investigate visual awareness, is presently unclear. Here, we examined prestimulus alpha activity in the electroencephalogram (EEG) of healthy participants in the context of a generalized flash suppression (GFS) task during which salient target stimuli are rendered subjectively invisible in a subset of trials following the onset of a full-field motion stimulus. Unlike for masking or threshold paradigms, alpha (8-12 Hz) amplitude prior to motion onset was significantly higher when targets remained subjectively visible compared to trials during which the targets became perceptually suppressed. Furthermore, individual prestimulus alpha amplitudes strongly correlated with the individual trial-to-trial variability quenching following motion stimulus onset, indicating that variability quenching in visual cortex is closely linked to prestimulus alpha activity. We conclude that predictive correlates of conscious perception derived from perceptual suppression paradigms differ substantially from those of obtained with “near threshold paradigms”, possibly reflecting the effectiveness of the suppressor stimulus.

scholarly journals Reduced alpha amplitudes predict perceptual suppression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eva Poland ◽  
Aishwarya Bhonsle ◽  
Iris Steinmann ◽  
Melanie Wilke
Keyword(s):  
Visual Awareness ◽  
Occipital Cortex ◽  
Threshold Level ◽  
Stimulus Onset ◽  
Alpha Activity ◽  
Motion Onset ◽  
Full Field ◽  
Motion Stimulus ◽  
The Individual ◽  
Target Visibility

AbstractThe amplitude of prestimulus alpha oscillations over parieto-occipital cortex has been shown to predict visual detection of masked and threshold-level stimuli. Whether alpha activity similarly predicts target visibility in perceptual suppression paradigms, another type of illusion commonly used to investigate visual awareness, is presently unclear. Here, we examined prestimulus alpha activity in the electroencephalogram (EEG) of healthy participants in the context of a generalized flash suppression (GFS) task during which salient target stimuli are rendered subjectively invisible in a subset of trials following the onset of a full-field motion stimulus. Unlike for masking or threshold paradigms, alpha (8–12 Hz) amplitude prior to motion onset was significantly higher when targets remained subjectively visible compared to trials during which the targets became perceptually suppressed. Furthermore, individual prestimulus alpha amplitudes strongly correlated with the individual trial-to-trial variability quenching following motion stimulus onset, indicating that variability quenching in visual cortex is closely linked to prestimulus alpha activity. We conclude that predictive correlates of conscious perception derived from perceptual suppression paradigms differ substantially from those obtained with “near threshold paradigms”, possibly reflecting the effectiveness of the suppressor stimulus.

scholarly journals Alpha fluctuations regulate the accrual of visual information to awareness

2020 ◽  
Author(s):  
Mireia Torralba ◽  
Alice Drew ◽  
Alba Sabaté San José ◽  
Luis Morís Fernández ◽  
Salvador Soto-Faraco
Keyword(s):  
Binocular Rivalry ◽  
Visual Information ◽  
Brain Activity ◽  
Visual Awareness ◽  
Sensory Information ◽  
Occipital Cortex ◽  
Visual Inputs ◽  
Perceptual Alternation ◽  
Eeg Recordings ◽  
The Individual

AbstractEndogenous brain processes play a paramount role in shaping up perceptual phenomenology, as illustrated by the alternations experienced by humans (and other animals) when watching perceptually ambiguous, static images. Here, we hypothesised that endogenous alpha fluctuations in the visual cortex pace the accumulation of sensory information leading to perceptual outcomes. We addressed this hypothesis using binocular rivalry combined with visual entrainment and electroencephalography in humans (42 female, 40 male). The results revealed a correlation between the individual frequency of alpha oscillations in the occipital cortex and perceptual alternation rates experienced during binocular rivalry. In subsequent experiments we show that regulating endogenous brain activity via entrainment produced corresponding changes in perceptual alternation rate, which were observed only in the alpha range but not at lower entrainment frequencies. Overall, rhythmic alpha stimulation resulted in faster perceptual alternation rates, compared to arrhythmic or no stimulation. These findings support the notion that visual information is accumulated via alpha cycles to promote the emergence of conscious perceptual representations. We suggest that models of binocular rivalry incorporating posterior alpha as a pacemaker can provide an important advance in the comprehension of the dynamics of visual awareness.Significance statementMainstream theories in cognitive neuroscience agree that endogenous brain processes play a paramount role in shaping our perceptual experience of sensory inputs. In vision, endogenous fluctuations in the alpha rhythm have been pointed out to regulate visual inputs to perception. In support of this hypothesis, here we used EEG recordings and visual entrainment to demonstrate that inter-individual differences in the speed of endogenous alpha fluctuations in the brain are causally related to the accrual of visual information to awareness. These findings provide, for the first time, evidence for alpha-gated regulation of the dynamics of alternations in conscious visual perception.

scholarly journals The Rapid Extraction of Gist—Early Neural Correlates of High-level Visual Processing

2012 ◽  
Vol 24 (2) ◽  
pp. 521-529 ◽  
Author(s):  
Frank Oppermann ◽  
Uwe Hassler ◽  
Jörg D. Jescheniak ◽  
Thomas Gruber
Keyword(s):  
Visual Processing ◽  
Time Course ◽  
Occipital Cortex ◽  
Stimulus Onset ◽  
Gamma Band ◽  
Oscillatory Activity ◽  
Rapid Extraction ◽  
The Right ◽  
High Level ◽  
Individual Objects

The human cognitive system is highly efficient in extracting information from our visual environment. This efficiency is based on acquired knowledge that guides our attention toward relevant events and promotes the recognition of individual objects as they appear in visual scenes. The experience-based representation of such knowledge contains not only information about the individual objects but also about relations between them, such as the typical context in which individual objects co-occur. The present EEG study aimed at exploring the availability of such relational knowledge in the time course of visual scene processing, using oscillatory evoked gamma-band responses as a neural correlate for a currently activated cortical stimulus representation. Participants decided whether two simultaneously presented objects were conceptually coherent (e.g., mouse–cheese) or not (e.g., crown–mushroom). We obtained increased evoked gamma-band responses for coherent scenes compared with incoherent scenes beginning as early as 70 msec after stimulus onset within a distributed cortical network, including the right temporal, the right frontal, and the bilateral occipital cortex. This finding provides empirical evidence for the functional importance of evoked oscillatory activity in high-level vision beyond the visual cortex and, thus, gives new insights into the functional relevance of neuronal interactions. It also indicates the very early availability of experience-based knowledge that might be regarded as a fundamental mechanism for the rapid extraction of the gist of a scene.

Multimodal Ternus: Visual, Tactile, and Visuo — Tactile Grouping in Apparent Motion

Perception ◽  
10.1068/p5844 ◽  
2007 ◽  
Vol 36 (10) ◽  
pp. 1455-1464 ◽  
Author(s):  
Vanessa Harrar ◽  
Laurence R Harris
Keyword(s):  
Stimulus Onset Asynchrony ◽  
Apparent Motion ◽  
Visual Stimuli ◽  
Stimulus Onset ◽  
Light Touch ◽  
Visual Group ◽  
Motion Stimulus ◽  
Group Motion ◽  
Onset Asynchrony

Gestalt rules that describe how visual stimuli are grouped also apply to sounds, but it is unknown if the Gestalt rules also apply to tactile or uniquely multimodal stimuli. To investigate these rules, we used lights, touches, and a combination of lights and touches, arranged in a classic Ternus configuration. Three stimuli (A, B, C) were arranged in a row across three fingers. A and B were presented for 50 ms and, after a delay, B and C were presented for 50 ms. Subjects were asked whether they perceived AB moving to BC (group motion) or A moving to C (element motion). For all three types of stimuli, at short delays, A to C dominated, while at longer delays AB to BC dominated. The critical delay, where perception changed from group to element motion, was significantly different for the visual Ternus (3 lights, 162 ms) and the tactile Ternus (3 touches, 195 ms). The critical delay for the multimodal Ternus (3 light – touch pairs, 161 ms) was not different from the visual or tactile Ternus effects. In a second experiment, subjects were exposed to 2.5 min of visual group motion (stimulus onset asynchrony = 300 ms). The exposure caused a shift in the critical delay of the visual Ternus, a trend in the same direction for the multimodal Ternus, but no shift in the tactile Ternus. These results suggest separate but similar grouping rules for visual, tactile, and multimodal stimuli.

P1-15 Face-sensitive neural responses in the occipital cortex without visual awareness

2010 ◽  
Vol 121 ◽  
pp. S104
Author(s):  
T. Mistudo ◽  
Y. Kamio ◽  
Y. Goto ◽  
T. Nakashima ◽  
S. Tobimatsu
Keyword(s):  
Visual Awareness ◽  
Occipital Cortex ◽  
Neural Responses

Image evaluation and breast density categories as a function of mammary positioning in full-field digital mammography

2019 ◽  
Vol 61 (7) ◽  
pp. 868-874
Author(s):  
Irene Tomoko Nakano ◽  
Gabriel Lucca de Oliveira Salvador ◽  
Hugo Reuters Schelin ◽  
Valeriy Denyak ◽  
Helen Jamil Khoury ◽  
...  
Keyword(s):  
Breast Density ◽  
Area Under The Curve ◽  
Quality Criteria ◽  
Roc Curves ◽  
Full Field ◽  
European Guidelines ◽  
Full Field Digital Mammography ◽  
Definition Of ◽  
The Individual ◽  
The Right

Background Appropriate mammary positioning is an important factor in optimizing image quality in mammography (MMG). Purpose To study the correlation of quality criteria and breast density classification proposed by the American College of Radiology (ACR) and European Guidelines and its influence to achieve a proper positioning, therefore an adequate MMG. Material and methods A total of 128 routine MMG examinations were reviewed for the definition of breast composition parenchyma and assessment of several quality criteria proposed by the ACR and European Guidelines to achieve an adequate MMG. Adequate MMG was defined as a difference between the posterior nipple line (PNL), difference of the mediolateral oblique (MLO) and craniocaudal (CC) incidences > 1 cm. The quality criteria were analyzed as a function of correlation coefficient in order to evaluate the individual impact of each factor and analysis of variance (ANOVA) for all criteria. Receiver operating characteristic (ROC) curves were plotted to evaluate the performance of the criteria on each type of parenchyma. Results Negative correlation of fatty breasts and visibility of the mammary angle, a greater number of skin folds and PNL > 1 cm (r < 0). Dense MMG presented less visibility of the lateral tissue compared with other categories. Area under the curve of ROC analysis revealed values of 53.1% and 54.7% for the right and left breasts, respectively. Conclusion Several factors influenced in the MMG process, but we find that breast parenchyma has a substantial role in affecting these criteria and therefore a correct position for diagnosis, which could compromise MMG diagnostic performance.

Interhemispheric EEG asymmetries during unilateral bright-light exposure and subsequent sleep in humans

2008 ◽  
Vol 294 (3) ◽  
pp. R1053-R1060 ◽  
Author(s):  
Christian Cajochen ◽  
Rosalba Di Biase ◽  
Makoto Imai
Keyword(s):  
Visual Cortex ◽  
Time Course ◽  
Visual Stimulation ◽  
Light Exposure ◽  
Bright Light ◽  
Occipital Cortex ◽  
Alpha Activity ◽  
Hemispheric Dominance ◽  
Eeg Activity ◽  
The Right

We tested whether evening exposure to unilateral photic stimulation has repercussions on interhemispheric EEG asymmetries during wakefulness and later sleep. Because light exerts an alerting response in humans, which correlates with a decrease in waking EEG theta/alpha-activity and a reduction in sleep EEG delta activity, we hypothesized that EEG activity in these frequency bands show interhemispheric asymmetries after unilateral bright light (1,500 lux) exposure. A 2-h hemi-field light exposure acutely suppressed occipital EEG alpha activity in the ipsilateral hemisphere activated by light. Subjects felt more alert during bright light than dim light, an effect that was significantly more pronounced during activation of the right than the left visual cortex. During subsequent sleep, occipital EEG activity in the delta and theta range was significantly reduced after activation of the right visual cortex but not after stimulation of the left visual cortex. Furthermore, hemivisual field light exposure was able to shift the left predominance in occipital spindle EEG activity toward the stimulated hemisphere. Time course analysis revealed that this spindle shift remained significant during the first two sleep cycles. Our results reflect rather a hemispheric asymmetry in the alerting action of light than a use-dependent recovery function of sleep in response to the visual stimulation during prior waking. However, the observed shift in the spindle hemispheric dominance in the occipital cortex may still represent subtle local use-dependent recovery functions during sleep in a frequency range different from the delta range.

Relation between baroreflex sensitivity and cardiac vagal tone in humans

1994 ◽  
Vol 266 (1) ◽  
pp. H21-H27 ◽  
Author(s):  
M. Kollai ◽  
G. Jokkel ◽  
I. Bonyhay ◽  
J. Tomcsanyi ◽  
A. Naszlady
Keyword(s):  
Baroreflex Sensitivity ◽  
Regression Line ◽  
Systolic Pressure ◽  
Vagal Tone ◽  
Threshold Level ◽  
Dominant Factor ◽  
Cardiac Vagal Tone ◽  
The Individual ◽  
Method R ◽  
Maximum Threshold

The extent of dependence of cardiac vagal tone on arterial baroreceptor input has been studied in 12 healthy, young adult subjects. Cardiac vagal tone was defined as the chang in R-R interval after complete cholinergic blockade by atropine. Baroreflex sensitivity was determined with the "Oxford-method": R-R interval was regressed against systolic pressure. The interindividual correlation between cardiac vagal tone and baroreflex sensitivity for falling pressures was found to be significant, but not close (R = 0.81, P = 0.002). In each subject, the baroreflex regression line for falling pressures was extrapolated to the post-atropine R-R interval level; 50 mmHg was considered as minimum and 80 mmHg as maximum threshold level for the integrated baroreflex. From the relation between the individual regression lines and the minimum and maximum threshold levels, it was concluded that cardiac vagal tone could be generated by both baroreflex-dependent and -independent mechanisms, the ratio of which varies in different individuals, with the baroreflex-dependent mechanism being the dominant factor.

scholarly journals Feature integration within discrete time windows

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Leila Drissi-Daoudi ◽  
Adrien Doerig ◽  
Michael H. Herzog
Keyword(s):  
Computational Model ◽  
Discrete Time ◽  
Time Windows ◽  
Temporal Integration ◽  
Sensory Information ◽  
Stimulus Onset ◽  
Feature Integration ◽  
Spatio Temporal ◽  
The Individual ◽  
Over Time

Abstract Sensory information must be integrated over time to perceive, for example, motion and melodies. Here, to study temporal integration, we used the sequential metacontrast paradigm in which two expanding streams of lines are presented. When a line in one stream is offset observers perceive all other lines to be offset too, even though they are straight. When more lines are offset the offsets integrate mandatorily, i.e., observers cannot report the individual offsets. We show that mandatory integration lasts for up to 450 ms, depending on the observer. Importantly, integration occurs only when offsets are presented within a discrete window of time. Even stimuli that are in close spatio-temporal proximity do not integrate if they are in different windows. A window of integration starts with stimulus onset and integration in the next window has similar characteristics. We present a two-stage computational model based on discrete time windows that captures these effects.

Sign in / Sign up

Export Citation Format

Share Document