scholarly journals Computational analysis of the early stage of cuprous oxide sulphidation: a top-down process

2017 ◽  
Vol 52 (sup1) ◽  
pp. 50-53 ◽  
Author(s):  
J. H. Stenlid ◽  
A. J. Johansson ◽  
C. Leygraf ◽  
T. Brinck
Keyword(s):  
Cuprous Oxide ◽  
Computational Analysis ◽  
Early Stage ◽  
Top Down

scholarly journals Beliefs in being unlucky and deficits in executive functioning: An ERP study

2014 ◽  
Author(s):  
Jaime Martin del Campo ◽  
John Maltby ◽  
Giorgio Fuggetta
Keyword(s):  
Neural Activity ◽  
Attentional Control ◽  
Time Window ◽  
Early Stage ◽  
Selection Process ◽  
Reaction Times ◽  
Stimulus Onset ◽  
Event Related Potential ◽  
Control Group ◽  
Top Down

The present study tested the Dysexecutive Luck hypothesis by examining whether deficits in the early stage of top down attentional control led to an increase of neural activity in later stages of response related selection process among those who thought themselves to be unlucky. Individuals with these beliefs were compared to a control group using an Event-Related Potential (ERP) measure assessing underlying neural activity of semantic inhibition while completing a Stroop test. Results showed stronger main interference effects in the former group, via greater reaction times and a more negative distributed scalp late ERP component during incongruent trials in the time window of 450 – 780 ms post stimulus onset. Further, less efficient maintenance of task set among the former group was associated with greater late ERP response-related activation to compensate for the lack of top-down attentional control. These findings provide electrophysiological evidence to support the Dysexecutive Luck hypothesis.

scholarly journals Different Top-Down Goals Modulate Early Stage of Attention Bias: Irrelevant Task Suppresses the N170 of Automatic Attention Allocation to Threat Faces

2020 ◽  
Author(s):  
Haoran Dou ◽  
Limei Liang ◽  
Jie Ma ◽  
Jiachen Lu ◽  
Wenhai Zhang ◽  
...  
Keyword(s):  
Early Stage ◽  
Attention Bias ◽  
Neural Mechanism ◽  
Attention Allocation ◽  
Top Down ◽  
Neutral Face ◽  
Fearful Face ◽  
Relevant Task ◽  
The Difference ◽  
Automatic Attention

Abstract Recent research has evidenced that stimulus-driven attention bias for threat can be modulated by top-down goals. However, it remains unclear how different top-down goals affect the early stage of attention processing and its early neural mechanism. We collected electroencephalographic data from 28 healthy volunteers during four inconsistent levels in a modified spatial cueing task according to cue validity and task relevance. Our data revealed that reaction time(RT) to the target in the irrelevant task were much slower than that in the relevant task. In the irrelevant task, we did not find the difference between the RTs to the fearful and neutral face. In the relevant task, we found RTs of fearful face were faster than that of neutral face in valid cue condition(weak inconsistent level), whereas the RTs of fearful face were slower than that of neutral face in invalid cue condition(medium inconsistent level). The ERPs results showed that in relevant task(weak, medium inconsistent levels), fearful face in cue position of the target evoked larger N170 amplitudes than neutral face did, whereas this effect was suppressed in irrelevant task(strong, very strong inconsistent levels). Besides, fearful face in cue position of the target also evoked larger vertex positive potential (VPP) amplitudes than the neutral face did in valid cue condition( weak inconsistent level). These results suggest that irrelevant task may inhibit the early attention allocation to the fearful face. Furthermore, the top-down processing modulates the early attention bias for threatening faces.

scholarly journals Mass graphs and their applications in top-down proteomics

2015 ◽  
Author(s):  
Qiang Kou ◽  
Si Wu ◽  
Nikola Tolić ◽  
Ljiljana Pasa-Tolić ◽  
Xiaowen Liu
Keyword(s):  
Mass Spectrometry ◽  
Early Stage ◽  
Gene Mutations ◽  
Mass Spectrometry Data ◽  
Histone H4 ◽  
Top Down ◽  
Data Set ◽  
Alignment Algorithms ◽  
Protein Functions ◽  
Top Down Mass Spectrometry

Although proteomics has made rapid progress in the past decade, researchers are still in the early stage of exploring the world of complex proteoforms, which are protein products with various primary structure alterations resulting from gene mutations, alternative splicing, post-translational modifications, and other biological processes. Proteoform identification is essential to mapping proteoforms to their biological functions as well as discovering novel proteoforms and new protein functions. Top-down mass spectrometry is the method of choice for identifying complex proteoforms because it provides a "bird view" of intact proteoforms. The combinatorial explosion of possible proteoforms, which may result in billions of possible proteoforms for one protein, makes proteoform identification a challenging computational problem. Here we propose a new data structure, called the mass graph, for efficiently representing proteoforms. In addition, we design mass graph alignment algorithms for proteoform identification by top-down mass spectrometry. Experiments on a histone H4 mass spectrometry data set showed that the proposed methods outperformed MS-Align-E in identifying complex proteoforms.

Voluntary and Stimulus-Induced Attention Detected as Motion Sensation

Perception ◽  
1993 ◽  
Vol 22 (5) ◽  
pp. 517-526 ◽  
Author(s):  
Okihide Hikosaka ◽  
Satoru Miyauchi ◽  
Shinsuke Shimojo
Keyword(s):  
Information Processing ◽  
Response Bias ◽  
Visual Information ◽  
Stimulus Change ◽  
Early Stage ◽  
Visual Information Processing ◽  
Salient Object ◽  
Voluntary Attention ◽  
Top Down ◽  
Bottom Up

Attention may be drawn passively to a visually salient object. We may also actively direct attention to an object of interest. Do the two kinds of attention, passive and active, interact and jointly influence visual information processing at some neural level? What happens if the passive and active attentions come into conflict? These questions were addressed with the aid of a novel psychophysical technique which reveals an attentional gradient as a sensation of motion in a line which is presented instantaneously. The subjects were asked to direct attention with voluntary effort: to the side opposite to a stimulus change, to an object with a predetermined colour, and to an object moving smoothly. In every case the same motion sensation was induced in the line from the attended side to the unattended side. This voluntary attention, however, can easily and quickly be distracted by a change in the periphery, though it can be regained within a period of 200 to 500 ms. The results suggest that the line motion can be induced in voluntary (top-down) as well as stimulus-driven (bottom-up) situations, thus indicating the truly attentional nature of the effect, rather than it being some kind of retinotopic sensory artifact or response bias. The results also suggest that these two kinds of attention have facilitatory effects acting together on a relatively early stage of visual information processing.

Processing of Rhythmic and Melodic Gestalts—An ERP Study

2006 ◽  
Vol 24 (2) ◽  
pp. 209-222 ◽  
Author(s):  
Christiane Neuhaus ◽  
Thomas R. Knӧsche
Keyword(s):  
Early Stage ◽  
Event Related Potentials ◽  
Random Time ◽  
Rhythmic Pattern ◽  
Top Down ◽  
Neural Correlate ◽  
Expectancy Violation ◽  
Random Sections ◽  
Related Potentials ◽  
Integration Effort

In two experiments with event-related potentials (ERPs), we investigated the formation of auditory Gestalts. For this purpose, we used tone sequences of different structure. In the first experiment, we contrasted a rhythmic section to a section with random time values, each embedded in rhythmically irregular context. In the second experiment, melodies were contrasted to randomized sequences. Nonmusicians either had to detect the rhythmic pattern or to memorize short tone excerpts. Random versions in both experiments evoked a significant increase in the amplitude of P1 and P2. Randomized rhythm sections also evoked a late sustained negative potential. The enlarged P1 and P2 for random sequences might reflect stronger integration effort, as the predictability of tone progression was low. Thus, already at the early stage of encoding, sequence processing might be top-down-driven. The late negativity for rhythmically random sections is possibly task-related, reflecting expectancy violation in terms of regularity, since a metrical grid of beats could not be established. The memorizing of tone excerpts did not evoke a late neural correlate. (169)

scholarly journals Beliefs in being unlucky and deficits in executive functioning: An ERP study

2014 ◽  
Author(s):  
Jaime Martin del Campo ◽  
John Maltby ◽  
Giorgio Fuggetta
Keyword(s):  
Neural Activity ◽  
Attentional Control ◽  
Time Window ◽  
Early Stage ◽  
Selection Process ◽  
Reaction Times ◽  
Stimulus Onset ◽  
Event Related Potential ◽  
Control Group ◽  
Top Down

The present study tested the Dysexecutive Luck hypothesis by examining whether deficits in the early stage of top down attentional control led to an increase of neural activity in later stages of response related selection process among those who thought themselves to be unlucky. Individuals with these beliefs were compared to a control group using an Event-Related Potential (ERP) measure assessing underlying neural activity of semantic inhibition while completing a Stroop test. Results showed stronger main interference effects in the former group, via greater reaction times and a more negative distributed scalp late ERP component during incongruent trials in the time window of 450 – 780 ms post stimulus onset. Further, less efficient maintenance of task set among the former group was associated with greater late ERP response-related activation to compensate for the lack of top-down attentional control. These findings provide electrophysiological evidence to support the Dysexecutive Luck hypothesis.

Preserved Expert Object Recognition in a Case of Visual Hemiagnosia

2018 ◽  
Vol 30 (2) ◽  
pp. 131-143 ◽  
Author(s):  
Johannes Rennig ◽  
Sonja Cornelsen ◽  
Helmut Wilhelm ◽  
Marc Himmelbach ◽  
Hans-Otto Karnath
Keyword(s):  
Object Recognition ◽  
Expert Knowledge ◽  
Early Stage ◽  
Visual Object ◽  
Top Down ◽  
Visual Stream ◽  
Object Processing ◽  
Visual Expertise ◽  
Everyday Objects ◽  
The Right

We examined a stroke patient (HWS) with a unilateral lesion of the right medial ventral visual stream, involving the right fusiform and parahippocampal gyri. In a number of object recognition tests with lateralized presentations of target stimuli, HWS showed significant symptoms of hemiagnosia with contralesional recognition deficits for everyday objects. We further explored the patient's capacities of visual expertise that were acquired before the current perceptual impairment became effective. We confronted him with objects he was an expert for already before stroke onset and compared this performance with the recognition of familiar everyday objects. HWS was able to identify significantly more of the specific (“expert”) than of the everyday objects on the affected contralesional side. This observation of better expert object recognition in visual hemiagnosia allows for several interpretations. The results may be caused by enhanced information processing for expert objects in the ventral system in the affected or the intact hemisphere. Expert knowledge could trigger top–down mechanisms supporting object recognition despite of impaired basic functions of object processing. More importantly, the current work demonstrates that top–down mechanisms of visual expertise influence object recognition at an early stage, probably before visual object information propagates to modules of higher object recognition. Because HWS showed a lesion to the fusiform gyrus and spared capacities of expert object recognition, the current study emphasizes possible contributions of areas outside the ventral stream to visual expertise.

scholarly journals Irrelevant task suppresses the N170 of automatic attention allocation to fearful faces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haoran Dou ◽  
Limei Liang ◽  
Jie Ma ◽  
Jiachen Lu ◽  
Wenhai Zhang ◽  
...  
Keyword(s):  
Attentional Bias ◽  
Early Stage ◽  
Neural Mechanism ◽  
Attention Allocation ◽  
Top Down ◽  
Fearful Faces ◽  
N170 Component ◽  
Significant Difference ◽  
Relevant Task ◽  
Automatic Attention

AbstractRecent researches have provided evidence that stimulus-driven attentional bias for threats can be modulated by top-down goals. However, it is highlight essential to indicate whether and to what extent the top-down goals can affect the early stage of attention processing and its early neural mechanism. In this study, we collected electroencephalographic data from 28 healthy volunteers with a modified spatial cueing task. The results revealed that in the irrelevant task, there was no significant difference between the reaction time (RT) of the fearful and neutral faces. In the relevant task, we found that RT of fearful faces was faster than that of neutral faces in the valid cue condition, whereas the RT of fearful faces was slower than that of neutral faces in the invalid cue condition. The N170 component in our study showed a similar result compared with RT. Specifically, we noted that in the relevant task, fearful faces in the cue position of the target evoked a larger N170 amplitude than neutral faces, whereas this effect was suppressed in the irrelevant task. These results suggest that the irrelevant task may inhibit the early attention allocation to the fearful faces. Furthermore, the top-down goals can modulate the early attentional bias for threatening facial expressions.

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