scholarly journals High-level visual processing despite lack of awareness: Evidence from event-related potentials in a case of selective metamorphopsia

2013 ◽  
Vol 13 (9) ◽  
pp. 1106-1106
Author(s):  
T. Schubert ◽  
D. Rothlein ◽  
T. Brothers ◽  
K. LeDoux ◽  
B. Gordon ◽  
...  
Keyword(s):  
Visual Processing ◽  
Event Related Potentials ◽  
Related Potentials ◽  
High Level

scholarly journals Lack of awareness despite complex visual processing: Evidence from event-related potentials in a case of selective metamorphopsia

2020 ◽  
Vol 117 (27) ◽  
pp. 16055-16064 ◽  
Author(s):  
Teresa M. Schubert ◽  
David Rothlein ◽  
Trevor Brothers ◽  
Emily L. Coderre ◽  
Kerry Ledoux ◽  
...  
Keyword(s):  
Cognitive Processing ◽  
Visual Processing ◽  
Visual Awareness ◽  
Event Related Potentials ◽  
Event Related Potential ◽  
N170 Component ◽  
Close Proximity ◽  
Word Detection ◽  
Related Potentials ◽  
High Level

Visual awareness is thought to result from integration of low- and high-level processing; instances of integration failure provide a crucial window into the cognitive and neural bases of awareness. We present neurophysiological evidence of complex cognitive processing in the absence of awareness, raising questions about the conditions necessary for visual awareness. We describe an individual with a neurodegenerative disease who exhibits impaired visual awareness for the digits 2 to 9, and stimuli presented in close proximity to these digits, due to perceptual distortion. We identified robust event-related potential responses indicating 1) face detection with the N170 component and 2) task-dependent target-word detection with the P3b component, despite no awareness of the presence of faces or target words. These data force us to reconsider the relationship between neural processing and visual awareness; even stimuli processed by a workspace-like cognitive system can remain inaccessible to awareness. We discuss how this finding challenges and constrains theories of visual awareness.

Selective Attention and Error Processing in an Illusory Conjunction Task

2005 ◽  
Vol 19 (3) ◽  
pp. 216-231 ◽  
Author(s):  
Albertus A. Wijers ◽  
Maarten A.S. Boksem
Keyword(s):  
Target Detection ◽  
Event Related Potentials ◽  
Illusory Conjunction ◽  
Conjunction Error ◽  
Error Related Negativity ◽  
Display Element ◽  
Related Potentials ◽  
Feature Error ◽  
High Level ◽  
Correct Target

Abstract. We recorded event-related potentials in an illusory conjunction task, in which subjects were cued on each trial to search for a particular colored letter in a subsequently presented test array, consisting of three different letters in three different colors. In a proportion of trials the target letter was present and in other trials none of the relevant features were present. In still other trials one of the features (color or letter identity) were present or both features were present but not combined in the same display element. When relevant features were present this resulted in an early posterior selection negativity (SN) and a frontal selection positivity (FSP). When a target was presented, this resulted in a FSP that was enhanced after 250 ms as compared to when both relevant features were present but not combined in the same display element. This suggests that this effect reflects an extra process of attending to both features bound to the same object. There were no differences between the ERPs in feature error and conjunction error trials, contrary to the idea that these two types of errors are due to different (perceptual and attentional) mechanisms. The P300 in conjunction error trials was much reduced relative to the P300 in correct target detection trials. A similar, error-related negativity-like component was visible in the response-locked averages in correct target detection trials, in feature error trials, and in conjunction error trials. Dipole modeling of this component resulted in a source in a deep medial-frontal location. These results suggested that this type of task induces a high level of response conflict, in which decision-related processes may play a major role.

scholarly journals A P300 Brain-Computer Interface With a Reduced Visual Field

2020 ◽  
Vol 14 ◽  
Author(s):  
Luiza Kirasirova ◽  
Vladimir Bulanov ◽  
Alexei Ossadtchi ◽  
Alexander Kolsanov ◽  
Vasily Pyatin ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Classification Accuracy ◽  
Peripheral Vision ◽  
Brain Computer Interface ◽  
Event Related Potentials ◽  
Computer Interface ◽  
Central Visual Field ◽  
P300 Speller ◽  
Related Potentials

A P300 brain-computer interface (BCI) is a paradigm, where text characters are decoded from event-related potentials (ERPs). In a popular implementation, called P300 speller, a subject looks at a display where characters are flashing and selects one character by attending to it. The selection is recognized as the item with the strongest ERP. The speller performs well when cortical responses to target and non-target stimuli are sufficiently different. Although many strategies have been proposed for improving the BCI spelling, a relatively simple one received insufficient attention in the literature: reduction of the visual field to diminish the contribution from non-target stimuli. Previously, this idea was implemented in a single-stimulus switch that issued an urgent command like stopping a robot. To tackle this approach further, we ran a pilot experiment where ten subjects operated a traditional P300 speller or wore a binocular aperture that confined their sight to the central visual field. As intended, visual field restriction resulted in a replacement of non-target ERPs with EEG rhythms asynchronous to stimulus periodicity. Changes in target ERPs were found in half of the subjects and were individually variable. While classification accuracy was slightly better for the aperture condition (84.3 ± 2.9%, mean ± standard error) than the no-aperture condition (81.0 ± 2.6%), this difference was not statistically significant for the entire sample of subjects (N = 10). For both the aperture and no-aperture conditions, classification accuracy improved over 4 days of training, more so for the aperture condition (from 72.0 ± 6.3% to 87.0 ± 3.9% and from 72.0 ± 5.6% to 97.0 ± 2.2% for the no-aperture and aperture conditions, respectively). Although in this study BCI performance was not substantially altered, we suggest that with further refinement this approach could speed up BCI operations and reduce user fatigue. Additionally, instead of wearing an aperture, non-targets could be removed algorithmically or with a hybrid interface that utilizes an eye tracker. We further discuss how a P300 speller could be improved by taking advantage of the different physiological properties of the central and peripheral vision. Finally, we suggest that the proposed experimental approach could be used in basic research on the mechanisms of visual processing.

scholarly journals Event-Related Potential Evidence of Enhanced Visual Processing in Auditory-Associated Cortex in Adults with Hearing Loss

2020 ◽  
Vol 25 (5) ◽  
pp. 237-248
Author(s):  
Maojin Liang ◽  
Jiahao Liu ◽  
Yuexin Cai ◽  
Fei Zhao ◽  
Suijun Chen ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Visual Processing ◽  
Event Related Potentials ◽  
Event Related Potential ◽  
Occipital Area ◽  
Mapping Analysis ◽  
Related Potentials ◽  
The Difference ◽  
The Right ◽  
Frontotemporal Area

Objective: The present study investigated the characteristics of visual processing in the auditory-associated cortex in adults with hearing loss using event-related potentials. Methods: Ten subjects with bilateral postlingual hearing loss were recruited. Ten age- and sex-matched normal-hearing subjects were included as controls. Visual (“sound” and “non-sound” photos)-evoked potentials were performed. The P170 response in the occipital area as well as N1 and N2 responses in FC3 and FC4 were analyzed. Results: Adults with hearing loss had higher P170 amplitudes, significantly higher N2 amplitudes, and shorter N2 latency in response to “sound” and “non-sound” photo stimuli at both FC3 and FC4, with the exception of the N2 amplitude which responded to “sound” photo stimuli at FC3. Further topographic mapping analysis revealed that patients had a large difference in response to “sound” and “non-sound” photos in the right frontotemporal area, starting from approximately 200 to 400 ms. Localization of source showed the difference to be located in the middle frontal gyrus region (BA10) at around 266 ms. Conclusions: The significantly stronger responses to visual stimuli indicate enhanced visual processing in the auditory-associated cortex in adults with hearing loss, which may be attributed to cortical visual reorganization involving the right frontotemporal cortex.

scholarly journals Anorexia nervosa and body dysmorphic disorder are associated with abnormalities in processing visual information

2015 ◽  
Vol 45 (10) ◽  
pp. 2111-2122 ◽  
Author(s):  
W. Li ◽  
T. M. Lai ◽  
C. Bohon ◽  
S. K. Loo ◽  
D. McCurdy ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Spatial Frequency ◽  
Visual Processing ◽  
Visual Information ◽  
Body Dysmorphic Disorder ◽  
High Spatial Frequency ◽  
Event Related Potentials ◽  
Visual Stream ◽  
N170 Component ◽  
Related Potentials

BackgroundAnorexia nervosa (AN) and body dysmorphic disorder (BDD) are characterized by distorted body image and are frequently co-morbid with each other, although their relationship remains little studied. While there is evidence of abnormalities in visual and visuospatial processing in both disorders, no study has directly compared the two. We used two complementary modalities – event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) – to test for abnormal activity associated with early visual signaling.MethodWe acquired fMRI and ERP data in separate sessions from 15 unmedicated individuals in each of three groups (weight-restored AN, BDD, and healthy controls) while they viewed images of faces and houses of different spatial frequencies. We used joint independent component analyses to compare activity in visual systems.ResultsAN and BDD groups demonstrated similar hypoactivity in early secondary visual processing regions and the dorsal visual stream when viewing low spatial frequency faces, linked to the N170 component, as well as in early secondary visual processing regions when viewing low spatial frequency houses, linked to the P100 component. Additionally, the BDD group exhibited hyperactivity in fusiform cortex when viewing high spatial frequency houses, linked to the N170 component. Greater activity in this component was associated with lower attractiveness ratings of faces.ConclusionsResults provide preliminary evidence of similar abnormal spatiotemporal activation in AN and BDD for configural/holistic information for appearance- and non-appearance-related stimuli. This suggests a common phenotype of abnormal early visual system functioning, which may contribute to perceptual distortions.

scholarly journals Human posterior parietal cortex responds to visual stimuli as early as peristriate occipital cortex

2018 ◽  
Author(s):  
Tamar I. Regev ◽  
Jonathan Winawer ◽  
Edden M. Gerber ◽  
Robert T. Knight ◽  
Leon Y. Deouell
Keyword(s):  
Visual Processing ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Intractable Epilepsy ◽  
Event Related Potentials ◽  
Visual Responses ◽  
Baseline Activity ◽  
Visual Areas ◽  
Related Potentials ◽  
Posterior Parietal

AbstractMuch of what is known about the timing of visual processing in the brain is inferred from intracranial studies in monkeys, with human data limited to mainly non-invasive methods with lower spatial resolution. Here, we estimated visual onset latencies from electrocorticographic (ECoG) recordings in a patient who was implanted with 112 sub-dural electrodes, distributed across the posterior cortex of the right hemisphere, for pre-surgical evaluation of intractable epilepsy. Functional MRI prior to surgery was used to determine boundaries of visual areas. The patient was presented with images of objects from several categories. Event Related Potentials (ERPs) were calculated across all categories excluding targets, and statistically reliable onset latencies were determined using a bootstrapping procedure over the single trial baseline activity in individual electrodes. The distribution of onset latencies broadly reflected the known hierarchy of visual areas, with the earliest cortical responses in primary visual cortex, and higher areas showing later responses. A clear exception to this pattern was robust, statistically reliable and spatially localized, very early responses on the bank of the posterior intra-parietal sulcus (IPS). The response in the IPS started nearly simultaneously with responses detected in peristriate visual areas, around 60 milliseconds post-stimulus onset. Our results support the notion of early visual processing in the posterior parietal lobe, not respecting traditional hierarchies, and give direct evidence for the upper limit of onset times of visual responses across the human cortex.

scholarly journals Pre-Stimulus Alpha-Band Phase Gates Afferent Visual Cortex Responses

2021 ◽  
Author(s):  
Wei Dou ◽  
Audrey Morrow ◽  
Luca Iemi ◽  
Jason Samaha
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Time Window ◽  
Event Related Potentials ◽  
Alpha Phase ◽  
Alpha Activity ◽  
Alpha Band ◽  
Visual Responses ◽  
Alpha Oscillations ◽  
Related Potentials

The neurogenesis of alpha-band (8-13 Hz) activity has been characterized across many different animal experiments. However, the functional role that alpha oscillations play in perception and behavior has largely been attributed to two contrasting hypotheses, with human evidence in favor of either (or both or neither) remaining sparse. On the one hand, alpha generators have been observed in relay sectors of the visual thalamus and are postulated to phasically inhibit afferent visual input in a feedforward manner 1-4. On the other hand, evidence also suggests that the direction of influence of alpha activity propagates backwards along the visual hierarchy, reflecting a feedback influence upon the visual cortex 5-9. The primary source of human evidence regarding the role of alpha phase in visual processing has been on perceptual reports 10-16, which could be modulated either by feedforward or feedback alpha activity. Thus, although these two hypotheses are not mutually exclusive, human evidence clearly supporting either one is lacking. Here, we present human subjects with large, high-contrast visual stimuli that elicit robust C1 event-related potentials (ERP), which peak between 70-80 milliseconds post-stimulus and are thought to reflect afferent primary visual cortex (V1) input 17-20. We find that the phase of ongoing alpha oscillations modulates the global field power (GFP) of the EEG during this first volley of stimulus processing (the C1 time-window). On the standard assumption 21-23 that this early activity reflects postsynaptic potentials being relayed to visual cortex from the thalamus, our results suggest that alpha phase gates visual responses during the first feed-forward sweep of processing.

scholarly journals Action-associated modulation of visual event-related potentials evoked by abstract and ecological stimuli

2018 ◽  
Author(s):  
Gábor Csifcsák ◽  
Viktória Roxána Balla ◽  
Vera Daniella Dalos ◽  
Tünde Kilencz ◽  
Edit Magdolna Biró ◽  
...  
Keyword(s):  
Visual Processing ◽  
Event Related Potentials ◽  
Hand Movements ◽  
Cortical Responses ◽  
Passive Viewing ◽  
Related Potentials ◽  
Stimulus Identity ◽  
Sensory Predictions ◽  
Sensory Attenuation ◽  
Predictive Processes

This study investigated the influence of action-associated predictive processes on visual event-related potentials (ERPs). In two experiments (N=17 and N=19), we sought evidence for sensory attenuation (SA) indexed by ERP amplitude reductions for self-induced stimuli when compared to passive viewing of the same images. We assessed if SA (1) is stronger for ecologically valid versus abstract stimuli (by comparing ERPs to pictures depicting hands versus checkerboards), (2) is specific to stimulus identity (certain versus uncertain action-effect contingencies), and (3) is sensitive to laterality of hand movements (dominant versus subdominant hand actions). We found reduced occipital responses for self-triggered hand stimuli very early, between 80-90 ms (C1 component), but this effect was absent for checkerboards. On the contrary, the P1 component (100-140 ms) was enhanced for all action-associated stimuli, and this effect proved to be sensitive to stimulus predictability for hands only. The parietal N1 component (170-190 ms) showed amplitude enhancement after right-hand movements for checkerboards only. Overall, our findings indicate that action-associated predictive processes attenuate early cortical responses to ecologically valid visual stimuli. Moreover, we propose that subsequent ERPs show amplitude enhancement that might result from the interaction between expectation-based SA and attention. Movement-initiated modulation of visual ERPs does not appear to show strong lateralization in healthy individuals, although the absence of lateralized effects cannot be excluded. These results can have implications for assessing the influence of action-associated predictions on visual processing in psychiatric disorders characterized by aberrant sensory predictions and alterations in hemispheric asymmetry, such as schizophrenia.

scholarly journals Altering sensorimotor simulation impacts early stages of facial expression processing depending on individual differences in alexithymic traits

2021 ◽  
Author(s):  
Arianna Schiano Lomoriello ◽  
Antonio Maffei ◽  
Sabrina Brigadoi ◽  
Paola Sessa
Keyword(s):  
Facial Expression ◽  
Facial Expressions ◽  
Visual Processing ◽  
Event Related Potentials ◽  
Simulation Models ◽  
Facial Mimicry ◽  
Early Stages ◽  
Related Potentials ◽  
Low Levels ◽  
Expression Processing

Simulation models of facial expressions suggest that posterior visual areas and brain areas underpinning sensorimotor simulations might interact to improve facial expression processing. According to these models, facial mimicry, a manifestation of sensorimotor simulation, may contribute to the visual processing of facial expressions by influencing early stages. The aim of this study was to assess whether and how sensorimotor simulation influences early stages of face processing, also investigating its relationship with alexithymic traits given that previous studies have suggested that individuals with high levels of alexithymic traits (vs. individuals with low levels of alexithymic traits) tend to use sensorimotor simulation to a lesser extent. We monitored P1 and N170 ERP components of the event-related potentials (ERP) in participants performing a fine discrimination task of facial expressions and animals, as a control condition. In half of the experiment, participants could freely use their facial mimicry whereas in the other half they had their facial mimicry blocked by a gel. Our results revealed that only individuals with lower compared to high alexithymic traits showed a larger modulation of the P1 amplitude as a function of the mimicry manipulation selectively for facial expressions (but not for animals), while we did not observe any modulation of the N170. Given the null results at the behavioural level, we interpreted the P1 modulation as compensative visual processing in individuals with low levels of alexithymia under conditions of interference on the sensorimotor processing, providing a preliminary evidence in favor of sensorimotor simulation models.

scholarly journals Accuracy in Archery Shooting is linked to the Amplitude of the ERP N1 to the Snap of Clicker

2021 ◽  
Vol 10 (1) ◽  
pp. 37-44
Author(s):  
Hayri Ertan ◽  
◽  
Suha Yagcioglu ◽  
Alpaslan Yılmaz ◽  
Pekcan Ungan ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Event Related Potentials ◽  
Operational Definition ◽  
Brain Potentials ◽  
Long Latency ◽  
Eeg Data ◽  
Continuous Eeg ◽  
Related Potentials ◽  
High Level ◽  
The Brain

An archer requires a well-balanced and highly reproducible release of the bowstring to attain high scores in competition. Recurve archers use a mechanical device called the “clicker” to check the draw length. The fall of the clicker that generates an auditory stimulus should evoke a response in the brain. The purpose of this study is to evaluate the event-related potentials during archery shooting as a response to the fall of the clicker. Fifteen high-level archers participated. An electro cap was placed on the archers’ scalps, and continuous EEG activity was recorded (digitized at 1000 Hz) and stored for off-line analysis. The EEG data were epoched beginning 200 ms before and lasting 800 ms after stimulus marker signals. An operational definition has been developed for classifying hits corresponding to hit and/or miss areas. The hit area enlarged gradually starting from the centre of the target (yellow: 10) to blue (6 score) by creating ten hit area indexes. It is found that the snap of the clicker during archery shooting evokes N1–P2 components of long-latency evoked brain potentials. N1 amplitudes are significantly higher in hit area than that of miss areas for the 2nd and 4th indexes with 95% confidence intervals and 90% confidence intervals for the 1st and 3rd indexes with 90% confidence intervals. We conclude that the fall of the clicker in archery shooting elicits an N1 response with higher amplitude. Although evoked potential amplitudes were higher in successful shots, their latencies were not significantly different from the unsuccessful ones.

Sign in / Sign up

Export Citation Format

Share Document