scholarly journals Layer-dependent multiplicative effects of spatial attention on contrast responses in human early visual cortex

2020 ◽  
Author(s):  
Fanhua Guo ◽  
Chengwen Liu ◽  
Chencan Qian ◽  
Zihao Zhang ◽  
Kaibao Sun ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Middle Layer ◽  
Additive Effect ◽  
List Type ◽  
Strong Nonlinearity ◽  
Top Down ◽  
Contrast Gain ◽  
Early Visual Cortex ◽  
Deep Layers

AbstractAttention mechanisms at different cortical layers of human visual cortex remain poorly understood. Using submillimeter-resolution fMRI at 7T, we investigated the effects of top-down spatial attention on the contrast responses across different cortical depths in human early visual cortex. Gradient echo (GE) T2* weighted BOLD signal showed an additive effect of attention on contrast responses across cortical depths. Compared to the middle cortical depth, attention modulation was stronger in the superficial and deep depths of V1, and also stronger in the superficial depth of V2 and V3. Using ultra-high resolution (0.3mm in-plane) balanced steady-state free precession (bSSFP) fMRI, a multiplicative scaling effect of attention was found in the superficial and deep layers, but not in the middle layer of V1. Attention modulation of low contrast response was strongest in the middle cortical depths, indicating baseline enhancement or contrast gain of attention modulation on feedforward input. Finally, the additive effect of attention on T2* BOLD can be explained by strong nonlinearity of BOLD signals from large blood vessels, suggesting multiplicative effect of attention on neural activity. These findings support that top-down spatial attention mainly operates through feedback connections from higher order cortical areas, and a distinct mechanism of attention may also be associated with feedforward input through subcortical pathway.HighlightsResponse or activity gain of spatial attention in superficial and deep layersContrast gain or baseline shift of attention in V1 middle layerNonlinearity of large blood vessel causes additive effect of attention on T2* BOLD

scholarly journals Layer-specific modulation of top-down spatial attention in human early visual cortex

2019 ◽  
Vol 19 (10) ◽  
pp. 169
Author(s):  
Peng Zhang ◽  
Chengwen Liu ◽  
chencan Qian ◽  
Zihao Zhang ◽  
Sheng He ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Top Down ◽  
Early Visual Cortex

scholarly journals Depth-resolved ultra-high field fMRI reveals feedback contributions to surface motion perception

2019 ◽  
Author(s):  
Ingo Marquardt ◽  
Peter De Weerd ◽  
Marian Schneider ◽  
Omer Faruk Gulban ◽  
Dimo Ivanov ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Motion Perception ◽  
High Field ◽  
Depth Distribution ◽  
Middle Layer ◽  
Bold Response ◽  
Ultra High Field ◽  
Surface Motion ◽  
Visual Hemifield ◽  
Early Visual Cortex

AbstractHuman visual surface perception has neural correlates in early visual cortex, but the extent to which feedback contributes to this activity is not well known. Feedback projections preferentially enter superficial and deep anatomical layers, while avoiding the middle layer, which provides a hypothesis for the cortical depth distribution of fMRI activity related to feedback in early visual cortex. Here, we presented human participants uniform surfaces on a dark, textured background. The grey surface in the left hemifield was either perceived as static or moving based on a manipulation in the right hemifield. Physically, the surface was identical in the left visual hemifield, so any difference in percept likely was related to feedback. Using ultra-high field fMRI, we report the first evidence for a depth distribution of activation in line with feedback during the (illusory) perception of surface motion. Our results fit with a signal re-entering in superficial depths of V1, followed by a feedforward sweep of the re-entered information through V2 and V3, as suggested by activity centred in the middle-depth levels of the latter areas. This positive modulation of the BOLD signal due to illusory surface motion was on top of a strong negative BOLD response in the cortical representation of the surface stimuli, which depended on the presence of texture in the background. Hence, the magnitude and sign of the BOLD response to the surface strongly depended on background properties, and was additionally modulated by the presence or absence of illusory motion perception in a manner compatible with feedback. In summary, the present study demonstrates the potential of depth resolved fMRI in tackling biomechanical questions on perception that so far were only within reach of invasive animal experimentation.

scholarly journals Selective Activation of the Deep Layers of the Human Primary Visual Cortex by Top-Down Feedback

2016 ◽  
Vol 26 (3) ◽  
pp. 371-376 ◽  
Author(s):  
Peter Kok ◽  
Lauren J. Bains ◽  
Tim van Mourik ◽  
David G. Norris ◽  
Floris P. de Lange
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Top Down ◽  
Selective Activation ◽  
Deep Layers

scholarly journals Top-Down Control of Human Visual Cortex by Frontal and Parietal Cortex in Anticipatory Visual Spatial Attention

2008 ◽  
Vol 28 (40) ◽  
pp. 10056-10061 ◽  
Author(s):  
S. L. Bressler ◽  
W. Tang ◽  
C. M. Sylvester ◽  
G. L. Shulman ◽  
M. Corbetta
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Parietal Cortex ◽  
Top Down ◽  
Human Visual Cortex ◽  
Visual Spatial Attention ◽  
Visual Spatial

scholarly journals Population Dynamics of Early Visual Cortex during Working Memory

2018 ◽  
Vol 30 (2) ◽  
pp. 219-233 ◽  
Author(s):  
Masih Rahmati ◽  
Golbarg T. Saber ◽  
Clayton E. Curtis
Keyword(s):  
Working Memory ◽  
Population Dynamics ◽  
Visual Cortex ◽  
Parietal Cortex ◽  
Visual Stimulus ◽  
Visual Stimulation ◽  
Brain Activity ◽  
Top Down ◽  
Population Activity ◽  
Early Visual Cortex

Although the content of working memory (WM) can be decoded from the spatial patterns of brain activity in early visual cortex, how populations encode WM representations remains unclear. Here, we address this limitation by using a model-based approach that reconstructs the feature encoded by population activity measured with fMRI. Using this approach, we could successfully reconstruct the locations of memory-guided saccade goals based on the pattern of activity in visual cortex during a memory delay. We could reconstruct the saccade goal even when we dissociated the visual stimulus from the saccade goal using a memory-guided antisaccade procedure. By comparing the spatiotemporal population dynamics, we find that the representations in visual cortex are stable but can also evolve from a representation of a remembered visual stimulus to a prospective goal. Moreover, because the representation of the antisaccade goal cannot be the result of bottom–up visual stimulation, it must be evoked by top–down signals presumably originating from frontal and/or parietal cortex. Indeed, we find that trial-by-trial fluctuations in delay period activity in frontal and parietal cortex correlate with the precision with which our model reconstructed the maintained saccade goal based on the pattern of activity in visual cortex. Therefore, the population dynamics in visual cortex encode WM representations, and these representations can be sculpted by top–down signals from frontal and parietal cortex.

scholarly journals Attending to What and Where: Background Connectivity Integrates Categorical and Spatial Attention

2018 ◽  
Vol 30 (9) ◽  
pp. 1281-1297 ◽  
Author(s):  
Alexa Tompary ◽  
Naseem Al-Aidroos ◽  
Nicholas B. Turk-Browne
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Temporal Cortex ◽  
Relevant Information ◽  
Neural Basis ◽  
Attentional Modulation ◽  
Temporal Correlations ◽  
Visual Areas ◽  
Early Visual Cortex ◽  
Ventral Temporal Cortex

Top–down attention prioritizes the processing of goal-relevant information throughout visual cortex based on where that information is found in space and what it looks like. Whereas attentional goals often have both spatial and featural components, most research on the neural basis of attention has examined these components separately. Here we investigated how these attentional components are integrated by examining the attentional modulation of functional connectivity between visual areas with different selectivity. Specifically, we used fMRI to measure temporal correlations between spatially selective regions of early visual cortex and category-selective regions in ventral temporal cortex while participants performed a task that benefitted from both spatial and categorical attention. We found that categorical attention modulated the connectivity of category-selective areas, but only with retinotopic areas that coded for the spatially attended location. Similarly, spatial attention modulated the connectivity of retinotopic areas only with the areas coding for the attended category. This pattern of results suggests that attentional modulation of connectivity is driven both by spatial selection and featural biases. Combined with exploratory analyses of frontoparietal areas that track these changes in connectivity among visual areas, this study begins to shed light on how different components of attention are integrated in support of more complex behavioral goals.

scholarly journals Layer-specificity in the effects of attention and working memory on activity in primary visual cortex

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Timo van Kerkoerle ◽  
Matthew W. Self ◽  
Pieter R. Roelfsema
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Neuronal Activity ◽  
Current Source ◽  
Memory Task ◽  
Neuronal Firing ◽  
Top Down ◽  
Attention Task ◽  
Early Visual Cortex

Abstract Neuronal activity in early visual cortex depends on attention shifts but the contribution to working memory has remained unclear. Here, we examine neuronal activity in the different layers of the primary visual cortex (V1) in an attention-demanding and a working memory task. A current-source density analysis reveales top-down inputs in the superficial layers and layer 5, and an increase in neuronal firing rates most pronounced in the superficial and deep layers and weaker in input layer 4. This increased activity is strongest in the attention task but it is also highly reliable during working memory delays. A visual mask erases the V1 memory activity, but it reappeares at a later point in time. These results provide new insights in the laminar circuits involved in the top-down modulation of activity in early visual cortex in the presence and absence of visual stimuli.

scholarly journals Visual working memory representations in visual and parietal cortex do not remap after eye movements

2019 ◽  
Author(s):  
Tao He ◽  
Matthias Ekman ◽  
Annelinde R.E. Vandenbroucke ◽  
Floris P. de Lange
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Eye Movements ◽  
Visual Field ◽  
Visual System ◽  
Visual Working Memory ◽  
Parietal Cortex ◽  
List Type ◽  
Early Visual Cortex

ABSTRACTIt has been suggested that our visual system does not only process stimuli that are directly available to our eyes, but also has a role in maintaining information in VWM over a period of seconds. It remains unclear however what happens to VWM representations in the visual system when we make saccades. Here, we tested the hypothesis that VWM representations are remapped within the visual system after making saccades. We directly compared the content of VWM for saccade and no-saccade conditions using MVPA of delay-related activity measured with fMRI. We found that when participants did not make a saccade, VWM representations were robustly present in contralateral early visual cortex. When making a saccade, VWM representations degraded in contralateral V1-V3 after the saccade shifted the location of the remembered grating to the opposite visual field. However, contrary to our hypothesis we found no evidence for the representations of the remembered grating at the saccadic target location in the opposite visual field, suggesting that there is no evidence for remapping of VWM in early visual cortex. Interestingly, IPS showed persistent VWM representations in both the saccade and no-saccade condition. Together, our results indicate that VWM representations in early visual cortex are not remapped across eye movements, potentially limiting the role of early visual cortex in VWM storage.HighlightsVisual working memory (VWM) representations do not remap after making saccadesEye movement degrade VWM representations in early visual cortex, limiting the role of early visual cortex in VWM storageParietal cortex shows persistent VWM representations across saccades

scholarly journals Top-down control of spatial memory visualization in early visual cortex

2019 ◽  
Vol 19 (10) ◽  
pp. 205
Author(s):  
Lora T Likova ◽  
Spero Nicolas ◽  
Christopher W Tyler ◽  
Kris Mineff
Keyword(s):  
Visual Cortex ◽  
Spatial Memory ◽  
Top Down ◽  
Early Visual Cortex
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