Later Stages Of Visual Processing Research Articles

The impact of fear and psychopathological symptoms on neural responses to naturalistic stimuli in adolescents

The presentation of real-world images can swiftly engage processing mechanisms within specific brain regions and neural pathways. In this study, we explore the effects of fear and psychopathological symptoms on neural processing of realistic stimuli during a free viewing naturalistic task in a sample of adolescents (11–16y). Thirty-one participants performed an experimental task consisting of the visualization of animal pictures according to three conditions - Snakes, Spiders, and Dogs - during EEG recordings. Dimensions of fear and psychopathological symptoms were previously assessed through The Fear Survey Schedule for Children- Revised and the Brief Symptom Inventory. Earlier and later visual processing was analyzed through ERP components’ peak amplitudes. The results show a robust effect of psychopathology-related dimensions in the visual processing of naturalistic images, suggesting an increase of neural activity at later stages of visual processing (at the N200 time window) in symptomatic adolescents, corroborating the role of psychopathological symptoms in modulating neural responses to naturalistic images, and also guiding clinicians by providing additional data on how symptomatic adolescents perceive and process reality.

Peculiarities of the Activity of the Brain Structures of People with Schizophrenia During the Categorization of Objects of Animate and Inanimate Nature

One of the features of the work of the brain of people suffering from schizophrenia is changes in the activity of their brain during visual categorization of animate and inanimate objects. The purpose of this study was to analyze the brain activity of people with schizophrenia and their visual categorization of objects with different semantic and physical characteristics. It was assumed that the patterns of brain activity in individuals with schizophrenia would differ from the group of healthy individuals both in the early and late stages of visual processing. Using the method of visual evoked potentials, we studied the features of brain activity in 25 people suffering from schizophrenia from 1 to 7 years old, when they categorized images of animate and inanimate nature, low and high spatial frequency. It was found that the amplitudes of P170 (N170) in the left and right posterior and central leads, as well as the amplitudes of P300 in the central lead in people with schizophrenia do not differ during categorization of animate and inanimate objects, which does not correspond to the data obtained earlier from the people without mental health abnormalities. The revealed result is important for a better understanding of the restructuring of the brain during visual perception of objects of different categories, which occurs during the development of schizophrenia.

The relationship between aesthetic preferences of people for ceramic tile design and neural responses: An event-related potential study.

The aesthetic preferences of people can determine the success of a design and are often closely related to design features. The discovery of designs that match user preferences can provide a reference for designers. Ceramic tiles are widely used in environmental design; however, little attention has been paid to the aesthetic preferences of people for tiles. This study aimed to explore the relationship between aesthetic preferences for tile design and neural responses. In this study, two groups of tiles with different preference levels were randomly presented to 16 participants, and their electroencephalograms were recorded. The mean amplitudes of event-related potentials were analyzed by ANOVA. The results showed that: (1) the aesthetic preferences of people for tiles could modulate brain activity; (2) tiles that people liked triggered higher N100 amplitudes; and (3) tiles that people disliked triggered higher P200 and late positive potential (LPP) amplitudes. These results suggest that N100, P200, and LPP are significantly related to the aesthetic preferences of people for ceramic tiles. The difference in N100 and P200 amplitudes indicates that participants developed aesthetic perceptions of the tiles in the early and middle stages of vision and formed different attention allocations to tiles with varying levels of aesthetic preference; in the middle and late stages of visual processing, the difference in the LPP amplitude indicates that the impression of people for tiles is further deepened in the later stage, forming a top-down emotion-driven evaluation. Exploring the relationship between the aesthetic preferences of people and neural responses is significant in establishing objective aesthetic judgment indicators for tiles and understanding the process of aesthetic cognition. This study provides relevant information for quantitative aesthetic assessments of environmental design, interior design, and marketing involving ceramic tiles.

How Our Perception and Confidence Are Altered Using Decision Cues.

Understanding how individuals utilize social information while making perceptual decisions and how it affects their decision confidence is crucial in a society. To date, very little has been known about perceptual decision-making in humans and the associated neural mediators under social influence. The present study provides empirical evidence of how individuals are manipulated by others' decisions while performing a face/car identification task. Subjects were significantly influenced by what they perceived as the decisions of other subjects, while the cues, in reality, were manipulated independently from the stimulus. Subjects, in general, tend to increase their decision confidence when their individual decision and the cues coincide, while their confidence decreases when cues conflict with their individual judgments, often leading to reversal of decision. Using a novel statistical model, it was possible to rank subjects based on their propensity to be influenced by cues. This was subsequently corroborated by an analysis of their neural data. Neural time series analysis revealed no significant difference in decision-making using social cues in the early stages, unlike neural expectation studies with predictive cues. Multivariate pattern analysis of neural data alludes to a potential role of the frontal cortex in the later stages of visual processing, which appeared to code the effect of cues on perceptual decision-making. Specifically, the medial frontal cortex seems to play a role in facilitating perceptual decision preceded by conflicting cues.

The perceptual continuity field is retinotopic

Visual perception is systematically biased towards input from the recent past: perceived orientation, numerosity, and face identity are pulled towards previously seen stimuli. To better understand the brain level at which serial dependence occurs, the present study examined its spatial tuning. In three experiments, serial dependence occurred between stimuli occupying the same retinal position. Serial dependence between stimuli at distant retinal locations was smaller, even when the stimuli occupied the same location in external space. The spatial window over which serial dependence occurs is thus retinotopic, but wide, suggesting that serial dependence occurs at late stages of visual processing.

Visual processing deficits in 22q11.2 Deletion Syndrome.

Carriers of the rare 22q11.2 microdeletion present with a high percentage of positive and negative symptoms and a high genetic risk for schizophrenia. Visual processing impairments have been characterized in schizophrenia, but less so in 22q11.2 Deletion Syndrome (DS). Here, we focus on visual processing using high-density EEG and source imaging in 22q11.2DS participants (N = 25) and healthy controls (N = 26) with an illusory contour discrimination task.Significant differences between groups emerged at early and late stages of visual processing. In 22q11.2DS, we first observed reduced amplitudes over occipital channels and reduced source activations within dorsal and ventral visual stream areas during the P1 (100–125 ms) and within ventral visual cortex during the N1 (150–170 ms) visual evoked components. During a later window implicated in visual completion (240–285 ms), we observed an increase in global amplitudes in 22q11.2DS. The increased surface amplitudes for illusory contours at this window were inversely correlated with positive subscales of prodromal symptoms in 22q11.2DS.The reduced activity of ventral and dorsal visual areas during early stages points to an impairment in visual processing seen both in schizophrenia and 22q11.2DS. During intervals related to perceptual closure, the inverse correlation of high amplitudes with positive symptoms suggests that participants with 22q11.2DS who show an increased brain response to illusory contours during the relevant window for contour processing have less psychotic symptoms and might thus be at a reduced prodromal risk for schizophrenia.

Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands.

A growing number of studies use the combination of eye-tracking and electroencephalographic (EEG) measures to explore the neural processes that underlie visual perception. In these studies, fixation-related potentials (FRPs) are commonly used to quantify early and late stages of visual processing that follow the onset of each fixation. However, FRPs reflect a mixture of bottom-up (sensory-driven) and top-down (goal-directed) processes, in addition to eye movement artifacts and unrelated neural activity. At present there is little consensus on how to separate this evoked response into its constituent elements. In this study we sought to isolate the neural sources of target detection in the presence of eye movements and over a range of concurrent task demands. Here, participants were asked to identify visual targets (Ts) amongst a grid of distractor stimuli (Ls), while simultaneously performing an auditory N-back task. To identify the discriminant activity, we used independent components analysis (ICA) for the separation of EEG into neural and non-neural sources. We then further separated the neural sources, using a modified measure-projection approach, into six regions of interest (ROIs): occipital, fusiform, temporal, parietal, cingulate, and frontal cortices. Using activity from these ROIs, we identified target from non-target fixations in all participants at a level similar to other state-of-the-art classification techniques. Importantly, we isolated the time course and spectral features of this discriminant activity in each ROI. In addition, we were able to quantify the effect of cognitive load on both fixation-locked potential and classification performance across regions. Together, our results show the utility of a measure-projection approach for separating task-relevant neural activity into meaningful ROIs within more complex contexts that include eye movements.

Electrophysiological correlates of visual binding errors after bilateral parietal damage

Illusory conjunctions (e.g. the confusion between the shape of one stimulus with the color of another stimulus) are the most dramatic expression of binding failures in vision. Under brief exposure or when attention is diverted illusory conjunctions may be observed in healthy participants, but they only represent a real-life problem for patients with parietal damage. However, it is unclear whether such failures reflect the impairment of early or late stages of visual processing. Here, we examined the time-course of visual processing using evoked potential measures in a patient with bilateral damage to the posterior parietal cortex presenting prominent binding failures. The patient was asked to identify colored letters that were briefly flashed to the left or right hemifield. When only one item was presented she adequately identified color or shape of left and right letters. In contrast, when presentation was bilateral she either identified the correct right shape-color combination and missed the item in the left hemifield (extinction) or combined incorrectly the right shape with the left color (illusory conjunction). Evoked potential analyses revealed a specific electrophysiological signature of illusory conjunctions, starting ∼105ms after stimulus onset over the right frontal cortex. These findings indicate that binding errors reflect failures of early stages of attentional filtering relying on the integrity of the posterior parietal cortex.

The Impact of Task Demands on Fixation-Related Brain Potentials during Guided Search.

Recording synchronous data from EEG and eye-tracking provides a unique methodological approach for measuring the sensory and cognitive processes of overt visual search. Using this approach we obtained fixation related potentials (FRPs) during a guided visual search task specifically focusing on the lambda and P3 components. An outstanding question is whether the lambda and P3 FRP components are influenced by concurrent task demands. We addressed this question by obtaining simultaneous eye-movement and electroencephalographic (EEG) measures during a guided visual search task while parametrically modulating working memory load using an auditory N-back task. Participants performed the guided search task alone, while ignoring binaurally presented digits, or while using the auditory information in a 0, 1, or 2-back task. The results showed increased reaction time and decreased accuracy in both the visual search and N-back tasks as a function of auditory load. Moreover, high auditory task demands increased the P3 but not the lambda latency while the amplitude of both lambda and P3 was reduced during high auditory task demands. The results show that both early and late stages of visual processing indexed by FRPs are significantly affected by concurrent task demands imposed by auditory working memory.

The duration compression effect is mediated by adaptation of both retinotopic and spatiotopic mechanisms

The duration compression effect is a phenomenon in which prior adaptation to a spatially circumscribed dynamic stimulus results in the duration of subsequent subsecond stimuli presented in the adapted region being underestimated. There is disagreement over the frame of reference within which the duration compression phenomenon occurs. One view holds that the effect is driven by retinotopic-tuned mechanisms located at early stages of visual processing, and an alternate position is that the mechanisms are spatiotopic and occur at later stages of visual processing (MT+). We addressed the retinotopic-spatiotopic question by using adapting stimuli – drifting plaids – that are known to activate global-motion mechanisms in area MT. If spatiotopic mechanisms contribute to the duration compression effect, drifting plaid adaptors should be well suited to revealing them. Following adaptation participants were tasked with estimating the duration of a 600ms random dot stimulus, whose direction was identical to the pattern direction of the adapting plaid, presented at either the same retinotopic or the same spatiotopic location as the adaptor. Our results reveal significant duration compression in both conditions, pointing to the involvement of both retinotopic-tuned and spatiotopic-tuned mechanisms in the duration compression effect.

The neural origins of visual crowding as revealed by event-related potentials and oscillatory dynamics

Visual crowding is the difficulty in perceiving a target in the presence of nearby flankers. Most neurophysiological studies of crowding employed functional neuroimaging, but because of its low temporal resolution, no definitive answer can be given to the question: is crowding arising at the earliest or at later stages of visual processing? Here, we used a classic letters crowding paradigm in combination with electroencephalography (EEG). We manipulated the critical space between peripheral target and flankers, while ensuring a proper control of basic stimulus characteristics. Analyses were focused on event-related potentials (ERPs) and oscillatory activity in the alpha (8–12 Hz), beta (15–30 Hz) and gamma (30–80 Hz) bands. At the ERP level, we found that the first sign of a crowding-induced modulation of EEG activity was a suppression of the N1 component. Oscillatory analysis revealed an early stimulus-evoked gamma enhancement and a later alpha reduction that, however, were not influenced by the amount of crowding. Importantly, reduction in the beta band reflected the amount of crowding (i.e., stronger reduction for strong relative to mid crowding condition) and correlated with individual behavioral performance. Collectively, these findings show that crowding for complex objects emerges at later stages of visual processing, possibly as a result of large-scale network interaction.

Aberrant intrinsic functional connectivity within and between corticostriatal and temporal-parietal networks in adults and youth with bipolar disorder.

Major questions remain regarding the dysfunctional neural circuitry underlying the pathophysiology of bipolar disorder (BD) in both youths and adults. In both age groups, studies implicate abnormal intrinsic functional connectivity among prefrontal, limbic and striatal areas. We collected resting-state functional magnetic resonance imaging (fMRI) data from youths and adults (ages 10-50 years) with BD (n = 39) and healthy volunteers (HV; n = 78). We identified brain regions with aberrant intrinsic functional connectivity in BD by first comparing voxel-wise mean global connectivity and then conducting correlation analyses. We used k-means clustering and multidimensional scaling to organize all detected regions into networks. Across the brain, we detected areas of dysconnectivity in both youths and adults with BD relative to HV. There were no significant age-group × diagnosis interactions. When organized by interregional connectivity, the areas of dysconnectivity in patients with BD comprised two networks: one of temporal and parietal areas involved in late stages of visual processing, and one of corticostriatal areas involved in attention, cognitive control and response generation. These data suggest that two networks show abnormal intrinsic functional connectivity in BD. Regions in these networks have been implicated previously in BD. We observed similar dysconnectivity in youths and adults with BD. These findings provide guidance for refining models of network-based dysfunction in BD.

Timing the impact of literacy on visual processing.

Learning to read requires the acquisition of an efficient visual procedure for quickly recognizing fine print. Thus, reading practice could induce a perceptual learning effect in early vision. Using functional magnetic resonance imaging (fMRI) in literate and illiterate adults, we previously demonstrated an impact of reading acquisition on both high- and low-level occipitotemporal visual areas, but could not resolve the time course of these effects. To clarify whether literacy affects early vs. late stages of visual processing, we measured event-related potentials to various categories of visual stimuli in healthy adults with variable levels of literacy, including completely illiterate subjects, early-schooled literate subjects, and subjects who learned to read in adulthood (ex-illiterates). The stimuli included written letter strings forming pseudowords, on which literacy is expected to have a major impact, as well as faces, houses, tools, checkerboards, and false fonts. To evaluate the precision with which these stimuli were encoded, we studied repetition effects by presenting the stimuli in pairs composed of repeated, mirrored, or unrelated pictures from the same category. The results indicate that reading ability is correlated with a broad enhancement of early visual processing, including increased repetition suppression, suggesting better exemplar discrimination, and increased mirror discrimination, as early as ∼ 100-150 ms in the left occipitotemporal region. These effects were found with letter strings and false fonts, but also were partially generalized to other visual categories. Thus, learning to read affects the magnitude, precision, and invariance of early visual processing.

Predicting faces and houses: Category-specific visual action-effect prediction modulates late stages of sensory processing

Our perception is fundamentally influenced by the way that we interact with the world. In particular, sensory events that are consistent with our planned actions are attenuated, both in terms of their phenomenology, and their neural response. Previous research in this domain has focused on simple-featured stimuli such as Gabor patches or sine wave tones, with attenuation normally occurring at early stages of sensory processing. In the current study we investigated this phenomenon using more ecologically valid stimuli that would likely involve higher-level visual predictions. More specifically, we trained participants to associate different actions with the presentation of a face or a house. By recording ERPs we could utilise the modularity of face processing to determine the locus of sensory attenuation for these high-level stimuli, as well as identify content-specific brain activity related to the prediction itself. In contrast to previous studies using low-level stimuli, we observed attenuation at later stages of visual processing, suggesting that higher-level predictions result in high-level prediction errors. We additionally observed significant differences over visual brain regions during action preparation dependent on whether participants were predicting to see a house or a face, perhaps reflecting preactivation of the predicted action effects. Furthermore, the degree to which participants showed evidence of preactivation, was correlated with the magnitude of their P2 attenuation. Taken together, these findings provide new insight into motor prediction and its influence on perception.

Abnormal late visual responses and alpha oscillations in neurofibromatosis type 1: a link to visual and attention deficits

BackgroundNeurofibromatosis type 1 (NF1) affects several areas of cognitive function including visual processing and attention. We investigated the neural mechanisms underlying the visual deficits of children and adolescents with NF1 by studying visual evoked potentials (VEPs) and brain oscillations during visual stimulation and rest periods.MethodsElectroencephalogram/event-related potential (EEG/ERP) responses were measured during visual processing (NF1 n = 17; controls n = 19) and idle periods with eyes closed and eyes open (NF1 n = 12; controls n = 14). Visual stimulation was chosen to bias activation of the three detection mechanisms: achromatic, red-green and blue-yellow.ResultsWe found significant differences between the groups for late chromatic VEPs and a specific enhancement in the amplitude of the parieto-occipital alpha amplitude both during visual stimulation and idle periods. Alpha modulation and the negative influence of alpha oscillations in visual performance were found in both groups.ConclusionsOur findings suggest abnormal later stages of visual processing and enhanced amplitude of alpha oscillations supporting the existence of deficits in basic sensory processing in NF1. Given the link between alpha oscillations, visual perception and attention, these results indicate a neural mechanism that might underlie the visual sensitivity deficits and increased lapses of attention observed in individuals with NF1.

Early and late stages of visual processing in individuals in prodromal state and first episode schizophrenia: An ERP study

BackgroundP300 deficits in schizophrenia patients are well established, especially in the auditory modality. Several studies have also reported P300 abnormalities in schizophrenia in visual tasks, but these findings are inconsistent. Furthermore, reports on P300 in visual modality in prodromal subjects are very limited. While P300 indexes relatively late and complex cognitive functions such as context updating in working memory, sensory-evoked components such as the P1/N1 primarily index early stages of perceptual processing. Several previous studies suggest that P300 reduction in schizophrenia patients may be dissociable from these earlier components. Therefore, in this study, we measured the P300 component as well as the P1/N1 in a visual oddball paradigm in prodromal subjects and first episode schizophrenia patients, and compared them with those of healthy controls. MethodVisual P300 and P1/N1 were obtained from prodromal (PRO, n=23), first episode schizophrenia patients (SZ, n=17), and healthy control subjects (HC, n=31), who silently counted infrequent target stimuli (“X”) amid standard stimuli (“Y”) presented on the screen while 64-channel EEG was recorded. ResultsBoth PRO and SZ subjects showed reduced P300 amplitudes and delayed P300 peak latencies in comparison to control subjects. On the other hand, N1 amplitude was significantly reduced only in SZ but not in PRO. Increased severity of positive symptoms was significantly associated with smaller P300 amplitude in PRO. ConclusionsThese results suggest that visual P300 is affected already at the prodromal stage and could be a marker of the prodromal phase of schizophrenia.

Just Another Social Scene: Evidence for Decreased Attention to Negative Social Scenes in High-Functioning Autism

The adaptive threat-detection advantage takes the form of a preferential orienting of attention to threatening scenes. In this study, we compared attention to social scenes in 15 high-functioning individuals with autism (ASD) and matched typically developing (TD) individuals. Eye-tracking was recorded while participants were presented with pairs of scenes, either emotional positive-neutral, emotional negative-neutral or neutral-neutral scenes. Early allocation of attention, the first image fixated in each pair, differed between groups: contrary to TD individuals who showed the typical threat-detection advantage towards negative images, the ASD group failed to show a bias toward threat-related scenes. Later processing of stimuli, indicated by the total fixation to the images during the 3-s presentation, was found unaffected in the ASD group. These results support the hypothesis of an early atypical allocation of attention towards natural social scenes in ASD, that is compensated in later stages of visual processing.

Changes in Early Cortical Visual Processing Predict Enhanced Reactivity in Deaf Individuals

Individuals with profound deafness rely critically on vision to interact with their environment. Improvement of visual performance as a consequence of auditory deprivation is assumed to result from cross-modal changes occurring in late stages of visual processing. Here we measured reaction times and event-related potentials (ERPs) in profoundly deaf adults and hearing controls during a speeded visual detection task, to assess to what extent the enhanced reactivity of deaf individuals could reflect plastic changes in the early cortical processing of the stimulus. We found that deaf subjects were faster than hearing controls at detecting the visual targets, regardless of their location in the visual field (peripheral or peri-foveal). This behavioural facilitation was associated with ERP changes starting from the first detectable response in the striate cortex (C1 component) at about 80 ms after stimulus onset, and in the P1 complex (100–150 ms). In addition, we found that P1 peak amplitudes predicted the response times in deaf subjects, whereas in hearing individuals visual reactivity and ERP amplitudes correlated only at later stages of processing. These findings show that long-term auditory deprivation can profoundly alter visual processing from the earliest cortical stages. Furthermore, our results provide the first evidence of a co-variation between modified brain activity (cortical plasticity) and behavioural enhancement in this sensory-deprived population.

Event-related potential correlates of the interaction between attention and spatiotemporal context regularity in vision

Visual perception is influenced at early processing stages by geometric spatiotemporal context regularities (consistent with the "vision-as-inference" view) and by attention, yet little is known about the interaction between these two influences on visual processing. Here, we investigate the temporal dynamics of the interaction between attention and spatiotemporal context regularity in target detection using event-related potentials (ERP). Spatial attention was withdrawn from the context by a secondary task in Experiment 1, and the role of task-relevance was explored in Experiment 2 by including a passive viewing condition. The ERP correlates of spatiotemporal regularity reported in an earlier study were replicated in single task (Experiment 1) and active viewing (Experiment 2): P1 and N1 peak-latency was shorter when the target was preceded by a context. Latency first differentiated between the two context conditions at N1, where latency was shortest for targets preceded by a context with both spatial and temporal regularities (compared with temporal regularity only). In dual task and passive viewing, this N1 latency-shift was abolished. Comparisons of "low-attention" (dual task or passive viewing) with "high-attention" conditions (single task or active viewing) revealed that attention only shortened N1 peak-latency when the target was preceded by stimulus sequences with spatial and temporal regularity. P1 latency was unaffected by manipulation of top-down attention factors. Attentional factors are likely to modulate influences of spatiotemporal context through re-afferent projections at later stages of visual processing in regions of extrastriate cortex associated with the generators of the N1 waveform.

Stress Potentiates Early and Attenuates Late Stages of Visual Processing

Stress can fundamentally alter neural responses to incoming information. Recent research suggests that stress and anxiety shift the balance of attention away from a task-directed mode, governed by prefrontal cortex, to a sensory-vigilance mode, governed by the amygdala and other threat-sensitive regions. A key untested prediction of this framework is that stress exerts dissociable effects on different stages of information processing. This study exploited the temporal resolution afforded by event-related potentials to disentangle the impact of stress on vigilance, indexed by early perceptual activity, from its impact on task-directed cognition, indexed by later postperceptual activity in humans. Results indicated that threat of shock amplified stress, measured using retrospective ratings and concurrent facial electromyography. Stress also double-dissociated early sensory-specific processing from later task-directed processing of emotionally neutral stimuli: stress amplified N1 (184-236 ms) and attenuated P3 (316-488 ms) activity. This demonstrates that stress can have strikingly different consequences at different processing stages. Consistent with recent suggestions, stress amplified earlier extrastriate activity in a manner consistent with vigilance for threat (N1), but disrupted later activity associated with the evaluation of task-relevant information (P3). These results provide a novel basis for understanding how stress can modulate information processing in everyday life and stress-sensitive disorders.