Visuocortical Processing Research Articles

How labels shape visuocortical processing in infants.

The current study examined the extent to which labels shape visuocortical processing during the first year of life during a brief (~6-min) associative learning task. Images of computer-generated artificial objects were paired with either individual-level (e.g., Jimmy, Boris) or category-level labels (e.g., Hitchel) while event-related potentials were recorded in response to the onset of the visual stimulus in 6- (n=41), 9- (n=27), and 12-month-old (n=28) infants. Analyses examined experience-dependent visuocortical changes within and across trials, label conditions, and ages. Overall, results demonstrate that infants deploy greater visuocortical resources during the first half of associative learning trials and to stimuli paired with category-level relative to individual-level labels. Waveform morphologies also differed between stimuli paired with individual- and category-level labels and across the age groups, with more complex deflections and amplitude differences between label type at 9- and 12-month-olds, but not 6-month-old infants. The present results highlight the importance of associative learning during infancy and suggest that category- versus individual-level labels differentially direct infant attention and visuocortical processing.

Sustained selective attention to chromatic information enhances visuocortical gain at the population level.

Prior work in selective attention research has shown that colour-selective attention enhances neural activity in visuocortical areas sensitive to the attended colour while suppressing activity in areas sensitive to ignored colours. However, it is currently unclear whether this effect is limited to attending to specific colour hues or extends to chromatic information more broadly. To investigate this question, we used steady-state visual evoked potentials (ssVEPs) frequency tagging to quantify participants' visuocortical responses to specific elements embedded in arrays of flickering, randomly moving mid-complex patterns. Participants were instructed to attend to either coloured or greyscale patterns while ignoring the others. We found that attending to either coloured or greyscale patterns produced robust increases in ssVEP amplitudes both compared to ignored stimuli and to baseline. There was however no evidence of suppressed responses to ignored patterns. These findings demonstrate that attentional selection based on the presence or absence of chromatic information prompts selectively enhanced visuocortical processing but this selective amplification is not accompanied by suppression of unattended stimuli. Findings are consistent with theoretical notions that predict strong competition between specific exemplars within a given feature dimension, such as red or green, but weak competition between broadly defined stimulus categories, such as chromatic versus non-chromatic.

A label isn't just a label: Brief training leads to label-dependent visuo-cortical processing in adults

The current study examines the extent to which hearing individual-level names (e.g., Jimmy) and category-level labels (e.g., Hitchel) paired with novel objects impacts neural responses across a brief (6 min) learning period. Event-related Potentials (ERPs) were recorded while adult participants (n = 44) viewed and heard exemplars of two different species of named novel objects. ERPs were examined for each labeling condition and compared across the first and second half of the learning trials (∼3 min/half). Mean amplitude decreased for the P1 and increased for the N170 from the first to the second half of trials. The decrease in P1 was right lateralized. In addition, the P1 amplitude recorded over right occipitotemporal regions was greater than left occipitotemporal areas, but only for objects paired with individual-level labels. Category-level labels did not show regional P1 differences. The N250 component was greatest over the right occipitotemporal region and was enhanced for objects labeled with individual-level relative to category-level names during the second half of trials. Overall, these findings highlight the unfolding of label-dependent visual processing across a short training period in adults. The results suggest that linguistic labels have an important, top-down impact, on visual processing and that label specificity shapes visuo-cortical responses within a 6-min learning period.

Single-session label training alters neural competition between objects and faces.

The extent to which visuocortical processing is altered when observers learn to categorize novel visual stimuli via labeling is not well understood. The present investigation used steady state visual evoked potential (ssVEP) frequency tagging to test the hypothesis that learning to categorize novel objects via labeling prompts a competitive advantage over concurrently presented stimuli. In the learning (label-training) phase, participants (n = 24) categorized objects according to two different species labels and faces according to gender. A control group (n = 26) viewed the same stimuli without label learning. Before and after learning, faces and objects were superimposed and viewed concurrently while periodically turned on and off at unique temporal rates (5/s or 6/s). The spectral power of the ssVEP at each frequency was projected to an L2 (minimum) norm estimated source space, and competition between faces and objects was compared using permutation-controlled mass univariate t tests. Results showed that, only in the training group, learning to label novel objects led to a competitive advantage over faces across a network of occipito-temporal and fronto-parietal cortical regions. These changes were more pronounced in participants showing more improvement across the label learning phase. Together, the findings support the notion that learning to label novel object categories affects neural competition though recurrent neural interactions in regions commonly associated with visual perception and selective attention. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Electrophysiological dynamics of visuocortical processing in hoarding disorder.

Individuals with hoarding disorder (HD) typically perform worse than peers on neuropsychological tasks involving visual perception. Functional neuroimaging shows diffusely increased activity in the visual cortex, consistent with inefficient visual processing in HD. The temporal locus of these inefficiencies in HD is unknown. This study examined the temporal unfolding of visual event-related brain potentials (ERPs) to help better define the neurophysiological mechanisms underlying visual dysfunction in HD. Thirty-three individuals with HD and 35 healthy controls (HC) were assessed using a 64-channel EEG during a modified flanker task. Permutation-controlled analyses were conducted to detect group differences in visual evoked ERPs on a millisecond-to-millisecond basis. Bayesian ANCOVAs and linear regressions that included hoarding and age were conducted to identify the best-fit model for the identified VEPs, compared to a null model that included depression and anxiety severity. Three temporal regions (175ms, 270ms, and 440ms), showed differences in amplitude between HD and HC and were consistent with ERP components N1, P1/N2, and a late negative slow wave (LNSW), respectively. After controlling for depression and anxiety, HD demonstrated an enhanced ERP amplitude at N1 and an attenuated amplitude in LNSW compared to HC but did not show differences at P1/N2. For the N1 and LNSW, there was also a primary effect of the interaction between hoarding and age. This study indicates that altered visuocortical reactivity in HD first occurs at the level of visuocortical processing after 170ms, indicating alterations of middle and later, but not early, processing in occipitotemporal visual cortex.

Single-session expertise training leads to competition between object and face representations in visuo-cortical processing

Single-session expertise training leads to competition between object and face representations in visuo-cortical processing

Selection of Visual Objects in Perception and Working Memory One at a Time

How does the content of visual working memory influence the way we process the visual environment? We addressed this question using the steady-state visual evoked potential (SSVEP), which provides a discernible measure of visuocortical activation to multiple stimuli simultaneously. Fifty-six adults were asked to remember a set of two oriented gratings. During the retention interval, two frequency-tagged oriented gratings were presented to probe the visuocortical processing of matching versus mismatching orientations relative to the memory set. Matching probes prompted an increased visuocortical response, whereas mismatching stimuli were suppressed. This suggests that the visual cortex prioritizes attentional selection of memory-relevant features at the expense of non-memory-relevant features. When two memory items were probed simultaneously, visuocortical amplification alternated between the two stimuli at a rate of 3 Hz to 4 Hz, consistent with the rate of attentional sampling of sensory events from the external world. These results suggest a serial, single-item attentional sampling of remembered features.

The effect of emotionally valenced eye region images on visuocortical processing of surprised faces.

In this study, we presented pictorial representations of happy, neutral, and fearful expressions projected in the eye regions to determine whether the eye region alone is sufficient to produce a context effect. Participants were asked to judge the valence of surprised faces that had been preceded by a picture of an eye region. Behavioral results showed that affective ratings of surprised faces were context dependent. Prime-related ERPs with presentation of happy eyes elicited a larger P1 than those for neutral and fearful eyes, likely due to the recognition advantage provided by a happy expression. Target-related ERPs showed that surprised faces in the context of fearful and happy eyes elicited dramatically larger C1 than those in the neutral context, which reflected the modulation by predictions during the earliest stages of face processing. There were larger N170 with neutral and fearful eye contexts compared to the happy context, suggesting faces were being integrated with contextual threat information. The P3 component exhibited enhanced brain activity in response to faces preceded by happy and fearful eyes compared with neutral eyes, indicating motivated attention processing may be involved at this stage. Altogether, these results indicate for the first time that the influence of isolated eye regions on the perception of surprised faces involves preferential processing at the early stages and elaborate processing at the late stages. Moreover, higher cognitive processes such as predictions and attention can modulate face processing from the earliest stages in a top-down manner.

Attention mechanisms during predictable and unpredictable threat — A steady-state visual evoked potential approach

Fear is elicited by imminent threat and leads to phasic fear responses with selective attention, whereas anxiety is characterized by a sustained state of heightened vigilance due to uncertain danger. In the present study, we investigated attention mechanisms in fear and anxiety by adapting the NPU-threat test to measure steady-state visual evoked potentials (ssVEPs). We investigated ssVEPs across no aversive events (N), predictable aversive events (P), and unpredictable aversive events (U), signaled by four-object arrays (30s). In addition, central cues were presented during all conditions but predictably signaled imminent threat only during the P condition. Importantly, cues and context events were flickered at different frequencies (15Hz vs. 20Hz) in order to disentangle respective electrocortical responses. The onset of the context elicited larger electrocortical responses for U compared to P context. Conversely, P cues elicited larger electrocortical responses compared to N cues. Interestingly, during the presence of the P cue, visuocortical processing of the concurrent context was also enhanced. The results support the notion of enhanced initial hypervigilance to unpredictable compared to predictable threat contexts, while predictable cues show electrocortical enhancement of the cues themselves but additionally a boost of context processing.

The Effect of Affective Context on Visuocortical Processing of Neutral Faces in Social Anxiety.

It has been demonstrated that verbal context information alters the neural processing of ambiguous faces such as faces with no apparent facial expression. In social anxiety, neutral faces may be implicitly threatening for socially anxious individuals due to their ambiguous nature, but even more so if these neutral faces are put in self-referential negative contexts. Therefore, we measured event-related brain potentials (ERPs) in response to neutral faces which were preceded by affective verbal information (negative, neutral, positive). Participants with low social anxiety (LSA; n = 23) and high social anxiety (HSA; n = 21) were asked to watch and rate valence and arousal of the respective faces while continuous EEG was recorded. ERP analysis revealed that HSA showed elevated P100 amplitudes in response to faces, but reduced structural encoding of faces as indexed by reduced N170 amplitudes. In general, affective context led to an enhanced early posterior negativity (EPN) for negative compared to neutral facial expressions. Moreover, HSA compared to LSA showed enhanced late positive potentials (LPP) to negatively contextualized faces, whereas in LSA this effect was found for faces in positive contexts. Also, HSA rated faces in negative contexts as more negative compared to LSA. These results point at enhanced vigilance for neutral faces regardless of context in HSA, while structural encoding seems to be diminished (avoidance). Interestingly, later components of sustained processing (LPP) indicate that LSA show enhanced visuocortical processing for faces in positive contexts (happy bias), whereas this seems to be the case for negatively contextualized faces in HSA (threat bias). Finally, our results add further new evidence that top-down information in interaction with individual anxiety levels can influence early-stage aspects of visual perception.

Raised middle-finger: electrocortical correlates of social conditioning with nonverbal affective gestures.

Humans form impressions of others by associating persons (faces) with negative or positive social outcomes. This learning process has been referred to as social conditioning. In everyday life, affective nonverbal gestures may constitute important social signals cueing threat or safety, which therefore may support aforementioned learning processes. In conventional aversive conditioning, studies using electroencephalography to investigate visuocortical processing of visual stimuli paired with danger cues such as aversive noise have demonstrated facilitated processing and enhanced sensory gain in visual cortex. The present study aimed at extending this line of research to the field of social conditioning by pairing neutral face stimuli with affective nonverbal gestures. To this end, electro-cortical processing of faces serving as different conditioned stimuli was investigated in a differential social conditioning paradigm. Behavioral ratings and visually evoked steady-state potentials (ssVEP) were recorded in twenty healthy human participants, who underwent a differential conditioning procedure in which three neutral faces were paired with pictures of negative (raised middle finger), neutral (pointing), or positive (thumbs-up) gestures. As expected, faces associated with the aversive hand gesture (raised middle finger) elicited larger ssVEP amplitudes during conditioning. Moreover, theses faces were rated as to be more arousing and unpleasant. These results suggest that cortical engagement in response to faces aversively conditioned with nonverbal gestures is facilitated in order to establish persistent vigilance for social threat-related cues. This form of social conditioning allows to establish a predictive relationship between social stimuli and motivationally relevant outcomes.

Electrophysiological Evidence for Biased Competition in V1 for Fear Expressions

When multiple stimuli are concurrently displayed in the visual field, they must compete for neural representation at the processing expense of their contemporaries. This biased competition is thought to begin as early as primary visual cortex, and can be driven by salient low-level stimulus features. Stimuli important for an organism's survival, such as facial expressions signaling environmental threat, might be similarly prioritized at this early stage of visual processing. In the present study, we used ERP recordings from striate cortex to examine whether fear expressions can bias the competition for neural representation at the earliest stage of retinotopic visuo-cortical processing when in direct competition with concurrently presented visual information of neutral valence. We found that within 50 msec after stimulus onset, information processing in primary visual cortex is biased in favor of perceptual representations of fear at the expense of competing visual information (Experiment 1). Additional experiments confirmed that the facial display's emotional content rather than low-level features is responsible for this prioritization in V1 (Experiment 2), and that this competition is reliant on a face's upright canonical orientation (Experiment 3). These results suggest that complex stimuli important for an organism's survival can indeed be prioritized at the earliest stage of cortical processing at the expense of competing information, with competition possibly beginning before encoding in V1.

ERP Evidence for Rapid Hedonic Evaluation of Logos

We know that human neurocognitive systems rapidly and implicitly evaluate emotionally charged stimuli. But what about more everyday, frequently encountered kinds of objects, such as computer desktop icons and business logos? Do we rapidly and implicitly evaluate these more prosaic visual images, attitude objects that might only engender a mild sense of liking or disliking, if at all? To address this question, we asked participants to view a set of unfamiliar commercial logos in the context of a target identification task as brain electrical responses to these objects were recorded via event-related potentials (ERPs). Following this task, participants individually identified those logos that were most liked or disliked, allowing us to then compare how ERP responses to logos varied as a function of hedonic evaluation-a procedure decoupling evaluative responses from any normative classification of the logos themselves. In Experiment 1, we found that visuocortical processing manifest a specific bias for disliked logos that emerged within the first 200 msec of stimulus onset. In Experiment 2, we replicated this effect while dissociating normative- and novelty-related influences. Taken together, our results provide direct electrophysiological evidence suggesting that we rapidly and implicitly evaluate commercial branding images at a hedonic level.

Perceptual load and visuocortical processing: event-related potentials reveal sensory-level selection.

Behavioral evidence suggests that the processing of parafoveal stimuli decreases as the perceptual demands of a task at fixation increase. However, it remains unclear whether or not this effect of perceptual load occurs during initial sensory-level processing at early stages of visuocortical analysis. Using event-related potential measures, we found that increasing the perceptual load of foveal targets led to a significant decrease in the sensory-evoked response to parafoveal stimuli. Moreover, these effects were observed using two different operational definitions of perceptual load. This result indicates that perceptual load affects the flow of information during the initial stages of visuocortical processing.