scholarly journals Failed Suppression of Salient Stimuli Precedes Behavioral Errors

2020 ◽  
Vol 32 (2) ◽  
pp. 367-377 ◽  
Author(s):  
Tobias Feldmann-Wüstefeld ◽  
Niko A. Busch ◽  
Anna Schubö
Keyword(s):  
Direct Evidence ◽  
Search Task ◽  
Time Window ◽  
Relevant Information ◽  
Limited Capacity ◽  
Attentional Resources ◽  
Signal Suppression ◽  
Neural Marker ◽  
Behavioral Index ◽  
In The Beginning

Our visual system is constantly confronted with more information than it can process. To deal with the limited capacity, attention allows us to enhance relevant information and suppress irrelevant information. Particularly, the suppression of salient irrelevant stimuli has shown to be important as it prevents attention to be captured and thus attentional resources to be wasted. This study aimed at directly connecting failures to suppress distraction with a neural marker of suppression, the distractor positivity (Pd). We measured participants' EEG signal while they performed a visual search task in which they had to report a digit inside a shape target while ignoring distractors, one of which could be a salient color singleton. Reports of target digits served as a behavioral index of enhancement, and reports of color distractor digits served as a behavioral index of failed suppression, each measured against reports of neutral distractor digits serving as a baseline. Participants reported the target identity more often than any distractor identity. The singleton identity was reported least often, suggesting suppression of the singleton below baseline. Suppression of salient stimuli was absent in the beginning and then increased throughout the experiment. When the singleton identity was reported, the Pd was observed in a later time window, suggesting that behavioral errors were preceded by failed suppression. Our results provide evidence for the signal suppression hypothesis that states salient items have to be actively suppressed to avoid attentional capture. Our results also provide direct evidence that the Pd is reflecting such active suppression.

Anterior mesendoderm induces mouse Engrailed genes in explant cultures

Development ◽  
1993 ◽  
Vol 118 (1) ◽  
pp. 139-149 ◽  
Author(s):  
S.L. Ang ◽  
J. Rossant
Keyword(s):  
Direct Evidence ◽  
Neural Tissue ◽  
Explant Culture ◽  
Neural Plate ◽  
Explant Cultures ◽  
Neural Marker ◽  
Engrailed Genes ◽  
Anterior Posterior

We have developed germ layer explant culture assays to study the role of mesoderm in anterior-posterior (A-P) patterning of the mouse neural plate. Using isolated explants of ectodermal tissue alone, we have demonstrated that the expression of Engrailed-1 (En-1) and En-2 genes in ectoderm is independent of mesoderm by the mid- to late streak stage, at least 12 hours before their onset of expression in the neural tube in vivo at the early somite stage. In recombination explants, anterior mesendoderm from headfold stage embryos induces the expression of En-1 and En-2 in pre- to early streak ectoderm and in posterior ectoderm from headfold stage embryos. In contrast, posterior mesendoderm from embryos of the same stage does not induce En genes in pre- to early streak ectoderm but is able to induce expression of a general neural marker, neurofilament 160 × 10(3) M(r). These results provide the first direct evidence for a role of mesendoderm in induction and regionalization of neural tissue in mouse.

scholarly journals Refixation control in free viewing: a specialized mechanism divulged by eye-movement-related brain activity

2018 ◽  
Vol 120 (5) ◽  
pp. 2311-2324 ◽  
Author(s):  
Andrey R. Nikolaev ◽  
Radha Nila Meghanathan ◽  
Cees van Leeuwen
Keyword(s):  
Eye Movement ◽  
Visual Information ◽  
Direct Evidence ◽  
Search Task ◽  
Visual Search Task ◽  
Brain Activity ◽  
Movement Control ◽  
Planning Stage ◽  
Eye Fixations ◽  
Free Viewing

In free viewing, the eyes return to previously visited locations rather frequently, even though the attentional and memory-related processes controlling eye-movement show a strong antirefixation bias. To overcome this bias, a special refixation triggering mechanism may have to be recruited. We probed the neural evidence for such a mechanism by combining eye tracking with EEG recording. A distinctive signal associated with refixation planning was observed in the EEG during the presaccadic interval: the presaccadic potential was reduced in amplitude before a refixation compared with normal fixations. The result offers direct evidence for a special refixation mechanism that operates in the saccade planning stage of eye movement control. Once the eyes have landed on the revisited location, acquisition of visual information proceeds indistinguishably from ordinary fixations. NEW & NOTEWORTHY A substantial proportion of eye fixations in human natural viewing behavior are revisits of recently visited locations, i.e., refixations. Our recently developed methods enabled us to study refixations in a free viewing visual search task, using combined eye movement and EEG recording. We identified in the EEG a distinctive refixation-related signal, signifying a control mechanism specific to refixations as opposed to ordinary eye fixations.

scholarly journals Changes in the Spatial Distribution of Visual Attention after Early Deafness

2002 ◽  
Vol 14 (5) ◽  
pp. 687-701 ◽  
Author(s):  
Jason Proksch ◽  
Daphne Bavelier
Keyword(s):  
Visual Field ◽  
Visual Attention ◽  
Visual Information ◽  
Search Task ◽  
Peripheral Visual Field ◽  
Auditory Deprivation ◽  
Attentional Processing ◽  
Attentional Resources ◽  
Visual Skills ◽  
Visual Tasks

There is much anecdotal suggestion of improved visual skills in congenitally deaf individuals. However, this claim has only been met by mixed results from careful investigations of visual skills in deaf individuals. Psychophysical assessments of visual functions have failed, for the most part, to validate the view of enhanced visual skills after deafness. Only a few studies have shown an advantage for deaf individuals in visual tasks. Interestingly, all of these studies share the requirement that participants process visual information in their peripheral visual field under demanding conditions of attention. This work has led us to propose that congenital auditory deprivation alters the gradient of visual attention from central to peripheral field by enhancing peripheral processing. This hypothesis was tested by adapting a search task from Lavie and colleagues in which the interference from distracting information on the search task provides a measure of attentional resources. These authors have established that during an easy central search for a target, any surplus attention remaining will involuntarily process a peripheral distractor that the subject has been instructed to ignore. Attentional resources can be measured by adjusting the difficulty of the search task to the point at which no surplus resources are available for the distractor. Through modification of this paradigm, central and peripheral attentional resources were compared in deaf and hearing individuals. Deaf individuals possessed greater attentional resources in the periphery but less in the center when compared to hearing individuals. Furthermore, based on results from native hearing signers, it was shown that sign language alone could not be responsible for these changes. We conclude that auditory deprivation from birth leads to compensatory changes within the visual system that enhance attentional processing of the peripheral visual field.

scholarly journals Mobile EEG identifies the re-allocation of attention during real-world activity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Simon Ladouce ◽  
David I. Donaldson ◽  
Paul A. Dudchenko ◽  
Magdalena Ietswaart
Keyword(s):  
Cognitive Processing ◽  
Sensory Processing ◽  
Real World ◽  
Event Related Potential ◽  
Limited Resources ◽  
Attentional Resources ◽  
Processing Demands ◽  
Neural Marker ◽  
Per Se ◽  
Human Participants

Abstract The distribution of attention between competing processing demands can have dramatic real-world consequences, however little is known about how limited attentional resources are distributed during real-world behaviour. Here we employ mobile EEG to characterise the allocation of attention across multiple sensory-cognitive processing demands during naturalistic movement. We used a neural marker of attention, the Event-Related Potential (ERP) P300 effect, to show that attention to targets is reduced when human participants walk compared to when they stand still. In a second experiment, we show that this reduction in attention is not caused by the act of walking per se. A third experiment identified the independent processing demands driving reduced attention to target stimuli during motion. ERP data reveals that the reduction in attention seen during walking reflects the linear and additive sum of the processing demands produced by visual and inertial stimulation. The mobile cognition approach used here shows how limited resources are precisely re-allocated according to the sensory processing demands that occur during real-world behaviour.

Cognitive aspects of social phobia: a review of theories and experimental research

2000 ◽  
Vol 15 (1) ◽  
pp. 59-66 ◽  
Author(s):  
C.Z. Musa ◽  
J.P. Lépine
Keyword(s):  
Social Phobia ◽  
Cognitive Processes ◽  
Cognitive Biases ◽  
Relevant Information ◽  
Memory Bias ◽  
Attentional Resources ◽  
Research Paradigms ◽  
Threatening Information ◽  
Cognitive Theories ◽  
Attention Memory

SummaryCognitive theories of social phobia have largely been inspired by the information-processing models of anxiety. They propose that cognitive biases can, at least partially, explain the etiology and maintenance of this disorder. A specific bias, conceived as a tendency to preferentially process socially-threatening information, has been proposed. This bias is thought to intervene in cognitive processes such as attention, memory and interpretation. Research paradigms adopted from experimental cognitive psychology and social psychology have been used to investigate these hypotheses. The existence of a bias in the allocation of attentional resources and the interpretation of information seems to be confirmed. A memory bias in terms of better retrieval for threat-relevant information appears to depend on specific encoding activities.

Informed Consent Revisited

1996 ◽  
Vol 5 (2) ◽  
pp. 214-220 ◽  
Author(s):  
Amnon Goldworth
Keyword(s):  
Informed Consent ◽  
Medical Treatment ◽  
Clinical Setting ◽  
Relevant Information ◽  
Best Interests ◽  
Limited Capacity ◽  
Legal Requirement ◽  
Good Level ◽  
Level Of Understanding ◽  
The Way

More than three decades after its introduction as a legal requirement for medical treatment in the clinical setting, informed consent continues to be viewed with skepticism as to its need or effectiveness. Some maintain that it is not required because the ordinary individual believes that doctors can be trusted to behave In the best interests of their patients. This issue will be discussed in a later portion of this article. Others are persuaded that informed consent is an unattainable ideal given the limited capacity of the ordinary individual to understand the relevant information. This view is supported by studies intended to show that satisfactory understanding on the part of patients cannot be achieved. In rebuttal, Apple-baum, Lidz, and Meisel observed that:Such statements are easily refuted by reference to studies of situations in which reasonable comprehension actually has been achieved. A sounder interpretation of all these studies might be that patients and subjects can attain a good level of understanding in many cases, but that several factors — including the manner in which disclosure is made as well as patients' limitations — may get in the way.

scholarly journals When Things Are Better or Worse than Expected: The Medial Frontal Cortex and the Allocation of Processing Resources

2006 ◽  
Vol 18 (7) ◽  
pp. 1112-1119 ◽  
Author(s):  
Geoffrey F. Potts ◽  
Laura E. Martin ◽  
Philip Burton ◽  
P. Read Montague
Keyword(s):  
Frontal Cortex ◽  
Temporal Distribution ◽  
Reward System ◽  
Relevant Information ◽  
Event Related Potential ◽  
Medial Frontal Cortex ◽  
Limited Capacity ◽  
Reward Prediction ◽  
System Input ◽  
Attention Selection

Access to limited-capacity neural systems of cognitive control must be restricted to the most relevant information. How the brain identifies and selects items for preferential processing is not fully understood. Anatomical models often place the selection mechanism in the medial frontal cortex (MFC), and one computational model proposes that the mesotelencephalic dopamine (DA) system, via its reward prediction properties, provides a “gate” through which information gains access to limited-capacity systems. There is a medial frontal event-related potential (ERP) index of attention selection, the anterior positivity (P2a), associated with DA reward system input to the MFC for the identification of task-relevant perceptual representations. The P2a has a similar spatio-temporal distribution as the medial frontal negativity (MFN), elicited to error responses or choices resulting in monetary loss. The MFN has also been linked to DA projections to the MFC but for action monitoring rather than attention selection. This study proposes that the P2a and the MFN reflect the same MFC evaluation function and use a passive reward prediction design containing neither instructed attention nor response to demonstrate that the ERP over medial frontal leads at the P2a/MFN latency is consistent with activity of midbrain DA neurons, positive to unpredicted rewards and negative when a predicted reward is withheld. This result suggests that MFC activity is regulated by DA reward system input and may function to identify items or actions that exceed or fail to meet motivational prediction.

scholarly journals Electrophysiological evidence for temporal dynamics associated with attentional processing in the zoom lens paradigm

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4538 ◽  
Author(s):  
Qing Zhang ◽  
Tengfei Liang ◽  
Jiafeng Zhang ◽  
Xueying Fu ◽  
Jianlin Wu
Keyword(s):  
Search Task ◽  
Attentional Focus ◽  
Visuospatial Attention ◽  
Zoom Lens ◽  
Lens Model ◽  
Attentional Processing ◽  
Attentional Resources ◽  
Electrophysiological Evidence ◽  
Attentional Scope ◽  
Concentric Circles

BackgroundVisuospatial processing requires wide distribution or narrow focusing of attention to certain regions in space. This mechanism is described by the zoom lens model and predicts an inverse correlation between the efficiency of processing and the size of the attentional scope. Little is known, however, about the exact timing of the effects of attentional scaling on visual searching and whether or not additional processing phases are involved in this process.MethodElectroencephalographic recordings were made while participants performed a visual search task under different attentional scaling conditions. Two concentric circles of different sizes, presented to the participants at the center of a screen modulated the attentional scopes, and search arrays were distributed in the space areas indicated by these concentric circles. To ensure consistent eccentricity of the search arrays across different conditions, we limited our studies to the neural responses evoked by the search arrays distributed in the overlapping region of different attentional scopes.ResultsConsistent with the prediction of the zoom lens model, our behavioral data showed that reaction times for target discrimination of search arrays decreased and the associated error rates also significantly decreased, with narrowing the attentional scope. Results of the event-related potential analysis showed that the target-elicited amplitude of lateral occipital N1, rather than posterior P1, which reflects the earliest visuospatial attentional processing, was sensitive to changes in the scaling of visuospatial attention, indicating that the modulation of the effect of changes in the spatial scale of attention on visual processing occurred after the delay period of P1. The N1 generator exhibited higher activity as the attentional scope narrowed, reflecting more intensive processing resources within the attentional focus. In contrast to N1, the amplitude of N2pc increased with the expansion of the attentional focus, suggesting that observers might further redistribute attentional resources according to the increased task difficulty.ConclusionThese findings provide electrophysiological evidence that the neural activity of the N1 generator is the earliest marker of the zoom lens effect of visual spatial attention. Furthermore, evidence from N2pc shows that there is also a redistribution of attentional resources after the action of the zoom lens mechanism, which allows for better perform of the search task in the context of low attentional resolution. On the basis of the timing of P1, N1, and N2pc, our findings provide compelling evidence that visuospatial attention processing in the zoom lens paradigm involves multi-stage dynamic processing.

scholarly journals Patient Selection For Acute Stroke Intravenous Thrombolysis

2017 ◽  
pp. 50
Author(s):  
Mehdi Farhoudi
Keyword(s):  
Time Window ◽  
Intravenous Thrombolysis ◽  
Recombinant Tissue Plasminogen Activator ◽  
Exclusion Criteria ◽  
Level Of Evidence ◽  
Analysis Of Results ◽  
Scientific Statement ◽  
Selection For ◽  
In The Beginning ◽  
Related Level

Stroke is a leading cause of mortality worldwide. Unfortunately its incidence is more and the age of occurrence is one decade earlier in our country, Iran. About 75-90 percent of stroke etiology is ischemic. The only approved drug treatment for eligible acute ischemic stroke (AIS) patients is thrombolytic therapy by recombinant tissue plasminogen activator (tPA). Related level of evidence is the highest (1a) and it has been approved by FDA following NINDS study since 1996. First golden time for use of tPA was less than 3 hours but later it has extended to 4.5 hours following re-analysis of the data since 2009. In the beginning, related exclusion criteria was strict considering many absolute items, however, some of them changed or removed as relative exclusion criteria by practicing and performing researches and analysis of results and it is going to be more simplified. For example, in 2013 there were 15 absolute and 10 relative exclusion criteria for intravenous thrombolysis in AIS in less than 4.5 hours period from onset of symptoms but in 2016 following publishing American heart and Stroke Association (AHA/ASA) scientific statement this criteria was more clarified and some of relative exclusion criteria removed. And finally new published researches extended this therapeutic time window to 6 hours by using mechanical thrombectomy in defined patients not responding to IV thrombolysis. In the ninth national Iranian Stroke Congress this updated criteria will be discussed.                

scholarly journals Be there on time: Spatial-temporal regularities guide young children’s attention in dynamic environments

2020 ◽  
Author(s):  
Nir Shalev ◽  
Sage Boettcher ◽  
Hannah Wilkinson ◽  
Gaia Scerif ◽  
Anna C. Nobre
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Real Life ◽  
Relevant Information ◽  
Dynamic Environments ◽  
Search Performance ◽  
Search Designs ◽  
Spatio Temporal ◽  
Extended Dynamic

It is believed that children have difficulties in guiding attention while facing distraction. However, developmental accounts of spatial attention rely on traditional search designs using static displays. In real life, dynamic environments can embed regularities that afford anticipation and benefit performance. We developed a dynamic visual-search task to test the ability of children to benefit from spatio-temporal regularities to detect goal-relevant targets appearing within an extended dynamic context amidst irrelevant distracting stimuli. We compared children and adults in detecting predictable vs. unpredictable targets fading in and out among competing distracting stimuli. While overall search performance was poorer in children, both groups detected more predictable targets. This effect was confined to task-relevant information. Additionally, we report how predictions are related to individual differences in attention. Altogether, our results indicate a striking capacity of prediction-led guidance towards task-relevant information in dynamic environments, refining traditional views about poor goal-driven attention in childhood.

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