scholarly journals Feature-specific patterns of attention and functional connectivity in human visual cortex

2019 ◽  
Author(s):  
Kirstie Wailes-Newson ◽  
Antony B Morland ◽  
Richard J. W. Vernon ◽  
Alex R. Wade
Keyword(s):  
Visual Stimulus ◽  
Critical Factor ◽  
Attentional Focus ◽  
Visual Features ◽  
Top Down ◽  
Bottom Up ◽  
Orientation Contrast ◽  
Visual Areas ◽  
Stimulus Features ◽  
Outstanding Question

AbstractAttending to different features of a scene can alter the responses of neurons in early- and mid- level visual areas but the nature of this change depends on both the (top down) attentional task and the (bottom up) visual stimulus. One outstanding question is the spatial scale at which cortex is modulated by attention to low-level stimulus features such as shape, contrast and orientation. It is unclear whether the recruitment of neurons to particular tasks occurs at an area level or at the level of intra-areal sub-populations, or whether the critical factor is a change in the way that areas communicate with each other. Here we use functional magnetic resonance imaging (fMRI) and psychophysics, to ask how areas known to be involved in processing different visual features (orientation, contrast and shape) are modulated as participants switch between tasks based on those features while the visual stimulus itself is effectively constant. At a univariate level, we find almost no feature-specific bottom-up or top-down responses in the areas we examine. However, multivariate analyses reveal a complex pattern of voxel-level modulation driven by attentional task. Connectivity analyses also demonstrate flexible and selective patterns of connectivity between early visual areas as a function of attentional focus. Overall, we find that attention alters the sensitivity and connectivity of neuronal subpopulations within individual early visual areas but, surprisingly, not the univariate response amplitudes of the areas themselves.

scholarly journals Bottom-up saliency and top-down learning in the primary visual cortex of monkeys

2018 ◽  
Vol 115 (41) ◽  
pp. 10499-10504 ◽  
Author(s):  
Yin Yan ◽  
Li Zhaoping ◽  
Wu Li
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Detection Task ◽  
Late Response ◽  
Late Component ◽  
Neuronal Responses ◽  
Top Down ◽  
Bottom Up ◽  
Response Component ◽  
Orientation Contrast

Early sensory cortex is better known for representing sensory inputs but less for the effect of its responses on behavior. Here we explore the behavioral correlates of neuronal responses in primary visual cortex (V1) in a task to detect a uniquely oriented bar—the orientation singleton—in a background of uniformly oriented bars. This singleton is salient or inconspicuous when the orientation contrast between the singleton and background bars is sufficiently large or small, respectively. Using implanted microelectrodes, we measured V1 activities while monkeys were trained to quickly saccade to the singleton. A neuron’s responses to the singleton within its receptive field had an early and a late component, both increased with the orientation contrast. The early component started from the outset of neuronal responses; it remained unchanged before and after training on the singleton detection. The late component started ∼40 ms after the early one; it emerged and evolved with practicing the detection task. Training increased the behavioral accuracy and speed of singleton detection and increased the amount of information in the late response component about a singleton’s presence or absence. Furthermore, for a given singleton, faster detection performance was associated with higher V1 responses; training increased this behavioral–neural correlate in the early V1 responses but decreased it in the late V1 responses. Therefore, V1’s early responses are directly linked with behavior and represent the bottom-up saliency signals. Learning strengthens this link, likely serving as the basis for making the detection task more reflexive and less top-down driven.

Attention-Generated Apparent Motion

2017 ◽  
Author(s):  
Zhong-Lin Lu ◽  
George Sperling
Keyword(s):  
Apparent Motion ◽  
Top Down ◽  
Third Order ◽  
Bottom Up ◽  
Motion Feature ◽  
Motion System ◽  
System A ◽  
Salient Stimulus ◽  
Stimulus Features ◽  
Salience Map

This chapter explores attention-generated apparent motion. A flickering display can seem to appear to move in opposite directions depending on which feature the observer attends to in the display. The illusory motion, generated by attention, demonstrates the mechanism of the third-order motion system: a dynamic salience map of the locations of the most salient stimulus features is determined jointly by stimulus strength (bottom-up) and by selective attention (top-down). Motion is computed directly and automatically from the salience map. Concepts covered in this chapter include apparent motion, first-order motion and second-order motion, feature tracking, salience maps, bottom-up processing, and top-down processing.

scholarly journals Characterizing the effects of feature salience and top-down attention in the early visual system

2017 ◽  
Vol 118 (1) ◽  
pp. 564-573 ◽  
Author(s):  
Sonia Poltoratski ◽  
Sam Ling ◽  
Devin McCormack ◽  
Frank Tong
Keyword(s):  
Visual System ◽  
Spatial Attention ◽  
Visual Processing ◽  
Visual Pathway ◽  
Additive Effects ◽  
Voluntary Attention ◽  
Top Down ◽  
Motion Direction ◽  
Bottom Up ◽  
Visual Areas

The visual system employs a sophisticated balance of attentional mechanisms: salient stimuli are prioritized for visual processing, yet observers can also ignore such stimuli when their goals require directing attention elsewhere. A powerful determinant of visual salience is local feature contrast: if a local region differs from its immediate surround along one or more feature dimensions, it will appear more salient. We used high-resolution functional MRI (fMRI) at 7T to characterize the modulatory effects of bottom-up salience and top-down voluntary attention within multiple sites along the early visual pathway, including visual areas V1–V4 and the lateral geniculate nucleus (LGN). Observers viewed arrays of spatially distributed gratings, where one of the gratings immediately to the left or right of fixation differed from all other items in orientation or motion direction, making it salient. To investigate the effects of directed attention, observers were cued to attend to the grating to the left or right of fixation, which was either salient or nonsalient. Results revealed reliable additive effects of top-down attention and stimulus-driven salience throughout visual areas V1–hV4. In comparison, the LGN exhibited significant attentional enhancement but was not reliably modulated by orientation- or motion-defined salience. Our findings indicate that top-down effects of spatial attention can influence visual processing at the earliest possible site along the visual pathway, including the LGN, whereas the processing of orientation- and motion-driven salience primarily involves feature-selective interactions that take place in early cortical visual areas. NEW & NOTEWORTHY While spatial attention allows for specific, goal-driven enhancement of stimuli, salient items outside of the current focus of attention must also be prioritized. We used 7T fMRI to compare salience and spatial attentional enhancement along the early visual hierarchy. We report additive effects of attention and bottom-up salience in early visual areas, suggesting that salience enhancement is not contingent on the observer’s attentional state.

What activates the human mirror neuron system during observation of artificial movements: Bottom-up visual features or top-down intentions?

2008 ◽  
Vol 46 (7) ◽  
pp. 2033-2042 ◽  
Author(s):  
Annerose Engel ◽  
Michael Burke ◽  
Katja Fiehler ◽  
Siegfried Bien ◽  
Frank Rösler
Keyword(s):  
Mirror Neuron System ◽  
Mirror Neuron ◽  
Visual Features ◽  
Top Down ◽  
Bottom Up ◽  
Neuron System

scholarly journals Top-down inhibition of irrelevant information indexed by alpha rhythms is disrupted in migraine

2021 ◽  
Author(s):  
Rémy Masson ◽  
Hesham A ElShafei ◽  
Geneviève Demarquay ◽  
Lesly Fornoni ◽  
Yohana Lévêque ◽  
...  
Keyword(s):  
Cognitive Processing ◽  
Gamma Activity ◽  
Auditory Target ◽  
Alpha Power ◽  
Top Down ◽  
Significant Group ◽  
Bottom Up ◽  
Power Increase ◽  
Visual Areas ◽  
Healthy Participants

There is growing evidence that migraine is associated with attentional abnormalities, both during and outside migraine attacks, which would impact the cognitive processing of sensory stimulation. However, these attention alterations are poorly characterized and their neurophysiological basis is still unclear. Nineteen migraineurs without aura and nineteen healthy participants were recruited to perform a task which used visually-cued auditory targets and distracting sounds to evaluate conjointly top-down and bottom-up attention mechanisms. Magnetoencephalography (MEG) signals were recorded. We investigated anticipatory alpha activity (power increase and decrease) and distractor-induced gamma activity as markers for top-down (inhibition and facilitation) and bottom-up attention, respectively. Compared to healthy participants, migraineurs presented a significantly less prominent alpha power increase in visual areas in anticipation of the auditory target, indexing a reduced inhibition of task-irrelevant visual areas. However, there was no significant group difference regarding the alpha power decrease in the relevant auditory cortices in anticipation of the target, nor regarding the distractor-induced gamma power increase in the ventral attention network. These results in the alpha band suggest that top-down inhibitory processes in the visual cortices are deficient in migraine but there is no clear evidence supporting a disruption of top-down facilitatory attentional processes. This relative inability to suppress irrelevant sensory information may be underlying the self-reported increased distractibility and contribute to sensory disturbances in migraine.

Bi-Directional Co-Attention Network for Image Captioning

2021 ◽  
Vol 17 (4) ◽  
pp. 1-20
Author(s):  
Weitao Jiang ◽  
Weixuan Wang ◽  
Haifeng Hu
Keyword(s):  
A Priori ◽  
Attention Mechanism ◽  
Superior Performance ◽  
Significant Advance ◽  
Visual Features ◽  
Image Captioning ◽  
Top Down ◽  
Bottom Up ◽  
Attention Network ◽  
Benchmark Datasets

Image Captioning, which automatically describes an image with natural language, is regarded as a fundamental challenge in computer vision. In recent years, significant advance has been made in image captioning through improving attention mechanism. However, most existing methods construct attention mechanisms based on singular visual features, such as patch features or object features, which limits the accuracy of generated captions. In this article, we propose a Bidirectional Co-Attention Network (BCAN) that combines multiple visual features to provide information from different aspects. Different features are associated with predicting different words, and there are a priori relations between these multiple visual features. Based on this, we further propose a bottom-up and top-down bi-directional co-attention mechanism to extract discriminative attention information. Furthermore, most existing methods do not exploit an effective multimodal integration strategy, generally using addition or concatenation to combine features. To solve this problem, we adopt the Multivariate Residual Module (MRM) to integrate multimodal attention features. Meanwhile, we further propose a Vertical MRM to integrate features of the same category, and a Horizontal MRM to combine features of the different categories, which can balance the contribution of the bottom-up co-attention and the top-down co-attention. In contrast to the existing methods, the BCAN is able to obtain complementary information from multiple visual features via the bi-directional co-attention strategy, and integrate multimodal information via the improved multivariate residual strategy. We conduct a series of experiments on two benchmark datasets (MSCOCO and Flickr30k), and the results indicate that the proposed BCAN achieves the superior performance.

scholarly journals Bottom-up and top-down influences at untrained conditions determine perceptual learning specificity and transfer

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ying-Zi Xiong ◽  
Jun-Yun Zhang ◽  
Cong Yu
Keyword(s):  
Perceptual Learning ◽  
Top Down ◽  
Transfer Condition ◽  
Bottom Up ◽  
Visual Neurons ◽  
Continuous Flash Suppression ◽  
Visual Areas ◽  
Suppression Technique ◽  
High Level ◽  
Additional Exposure

Perceptual learning is often orientation and location specific, which may indicate neuronal plasticity in early visual areas. However, learning specificity diminishes with additional exposure of the transfer orientation or location via irrelevant tasks, suggesting that the specificity is related to untrained conditions, likely because neurons representing untrained conditions are neither bottom-up stimulated nor top-down attended during training. To demonstrate these top-down and bottom-up contributions, we applied a “continuous flash suppression” technique to suppress the exposure stimulus into sub-consciousness, and with additional manipulations to achieve pure bottom-up stimulation or top-down attention with the transfer condition. We found that either bottom-up or top-down influences enabled significant transfer of orientation and Vernier discrimination learning. These results suggest that learning specificity may result from under-activations of untrained visual neurons due to insufficient bottom-up stimulation and/or top-down attention during training. High-level perceptual learning thus may not functionally connect to these neurons for learning transfer.

The Role of Top–Down Focused Spatial Attention in Preattentive Salience Coding and Salience-based Attentional Capture

2016 ◽  
Vol 28 (8) ◽  
pp. 1152-1165 ◽  
Author(s):  
Sabine Bertleff ◽  
Gereon R. Fink ◽  
Ralph Weidner
Keyword(s):  
Spatial Attention ◽  
Attentional Capture ◽  
Target Location ◽  
Search Display ◽  
Attentional Focus ◽  
Control Mechanisms ◽  
Top Down ◽  
Distractor Location ◽  
Bottom Up ◽  
Selective Visual Attention

Selective visual attention requires an efficient coordination between top–down and bottom–up attention control mechanisms. This study investigated the behavioral and neural effects of top–down focused spatial attention on the coding of highly salient distractors and their tendency to capture attention. Combining spatial cueing with an irrelevant distractor paradigm revealed bottom–up based attentional capture only when attention was distributed across the whole search display, including the distractor location. Top–down focusing spatial attention on the target location abolished attentional capture of a salient distractor outside the current attentional focus. Functional data indicated that the missing capture effect was not based on diminished bottom–up salience signals at unattended distractor locations. Irrespectively of whether salient distractors occurred at attended or unattended locations, their presence enhanced BOLD signals at their respective spatial representation in early visual areas as well as in inferior frontal, superior parietal, and medial parietal cortex. Importantly, activity in these regions reflected the presence of a salient distractor rather than attentional capture per se. Moreover, successfully inhibiting attentional capture of a salient distractor at an unattended location further increased neural responses in medial parietal regions known to be involved in controlling spatial attentional shifts. Consequently, data provide evidence that top–down focused spatial attention prevents automatic attentional capture by supporting attentional control processes counteracting a spatial bias toward a salient distractor.

scholarly journals Top-down directed attention to stimulus features and attentional allocation to bottom-up deviations

2008 ◽  
Vol 8 (15) ◽  
pp. 4-4 ◽  
Author(s):  
R. Sawaki ◽  
J. Katayama
Keyword(s):  
Top Down ◽  
Directed Attention ◽  
Bottom Up ◽  
Attentional Allocation ◽  
Stimulus Features
Sign in / Sign up

Export Citation Format

Share Document