scholarly journals Top–Down Modulation of Human Early Visual Cortex after Stimulus Offset Supports Successful Postcued Report

2011 ◽  
Vol 23 (8) ◽  
pp. 1921-1934 ◽  
Author(s):  
Claire Sergent ◽  
Christian C. Ruff ◽  
Antoine Barbot ◽  
Jon Driver ◽  
Geraint Rees
Keyword(s):  
Visual Cortex ◽  
Visual Stimulus ◽  
Sensory Processing ◽  
Time Window ◽  
Critical Time ◽  
Visual Display ◽  
Visual Presentation ◽  
Top Down ◽  
Early Visual Cortex ◽  
Stimulus Offset

Modulations of sensory processing in early visual areas are thought to play an important role in conscious perception. To date, most empirical studies focused on effects occurring before or during visual presentation. By contrast, several emerging theories postulate that sensory processing and conscious visual perception may also crucially depend on late top–down influences, potentially arising after a visual display. To provide a direct test of this, we performed an fMRI study using a postcued report procedure. The ability to report a target at a specific spatial location in a visual display can be enhanced behaviorally by symbolic auditory postcues presented shortly after that display. Here we showed that such auditory postcues can enhance target-specific signals in early human visual cortex (V1 and V2). For postcues presented 200 msec after stimulus termination, this target-specific enhancement in visual cortex was specifically associated with correct conscious report. The strength of this modulation predicted individual levels of performance in behavior. By contrast, although later postcues presented 1000 msec after stimulus termination had some impact on activity in early visual cortex, this modulation no longer related to conscious report. These results demonstrate that within a critical time window of a few hundred milliseconds after a visual stimulus has disappeared, successful conscious report of that stimulus still relates to the strength of top–down modulation in early visual cortex. We suggest that, within this critical time window, sensory representation of a visual stimulus is still under construction and so can still be flexibly influenced by top–down modulatory processes.

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 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 Brief stimuli cast a long-term trace in visual cortex

2021 ◽  
Author(s):  
Matthias Fritsche ◽  
Samuel G. Solomon ◽  
Floris P. de Lange
Keyword(s):  
Visual Cortex ◽  
Sensory Processing ◽  
Time Lags ◽  
Short Term ◽  
Statistical Representation ◽  
Specific Memory ◽  
Short Term Adaptation ◽  
Early Visual Cortex ◽  
Long Timescales

AbstractSensory processing and perception are strongly influenced by recent stimulus history – a phenomenon termed adaptation. While perception can be influenced even by brief stimuli presented dozens of seconds ago, neural adaptation to brief stimuli has not been observed beyond time lags of a few hundred milliseconds. Here, using an openly available dataset from the Allen Brain Observatory, we show that neurons in the early visual cortex of the mouse exhibit remarkably long timescales of adaptation in response to brief visual stimuli, persisting over dozens of seconds, despite the presentation of several intervening stimuli. Long-term adaptation was selectively expressed in cortical, but not in thalamic neurons, which only showed short-term adaptation. Visual cortex thus maintains concurrent stimulus-specific memory traces of past input that enable the visual system to build up a statistical representation of the world over multiple timescales, to efficiently represent information in a changing environment.

scholarly journals Cortical subnetworks encode context of visual stimulus

2018 ◽  
Author(s):  
Jordan P. Hamm ◽  
Yuriy Shymkiv ◽  
Shuting Han ◽  
Weijian Yang ◽  
Rafael Yuste
Keyword(s):  
Visual Cortex ◽  
Visual Stimulus ◽  
Sensory Processing ◽  
Calcium Imaging ◽  
Cortical Circuits ◽  
Fundamental Function ◽  
Stimulus Context ◽  
Contextual Modulation ◽  
Two Photon ◽  
Cortical Responses

AbstractCortical processing of sensory events is significantly influenced by context. For instance, a repetitive or redundant visual stimulus elicits attenuated cortical responses, but if the same stimulus is unexpected or “deviant”, responses are augmented. This contextual modulation of sensory processing is likely a fundamental function of neural circuits, yet an understanding of how it is computed is still missing. Using holographic two-photon calcium imaging in awake animals, here we identify three distinct, spatially intermixed ensembles of neurons in mouse primary visual cortex which differentially respond to the same stimulus under separate contexts, including a subnetwork which selectively responds to deviant events. These non-overlapping ensembles are distributed across layers 2-5, though deviance detection is more common in superficial layers. Contextual preferences likely arise locally since they are not present in bottom up inputs from the thalamus or top-down inputs from prefrontal cortex. The functional parcellation of cortical circuits into independent ensembles that encode stimulus context provides a circuit basis underlying cortically based perception of novel or redundant stimuli, a key deficit in many psychiatric disorders.One Sentence SummaryVisual cortex represents deviant and redundant stimuli with separate subnetworks.

scholarly journals Valence-dependent Disruption in Processing of Facial Expressions of Emotion in Early Visual Cortex—A Transcranial Magnetic Stimulation Study

2020 ◽  
Vol 32 (5) ◽  
pp. 906-916 ◽  
Author(s):  
Kun Guo ◽  
Lauren Calver ◽  
Yoshi Soornack ◽  
Patrick Bourke
Keyword(s):  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Facial Expressions ◽  
Magnetic Stimulation ◽  
Emotional Processing ◽  
Time Window ◽  
Neural Mechanism ◽  
Emotional Valence ◽  
Structure Information ◽  
Early Visual Cortex

Our visual inputs are often entangled with affective meanings in natural vision, implying the existence of extensive interaction between visual and emotional processing. However, little is known about the neural mechanism underlying such interaction. This exploratory transcranial magnetic stimulation (TMS) study examined the possible involvement of the early visual cortex (EVC, Area V1/V2/V3) in perceiving facial expressions of different emotional valences. Across three experiments, single-pulse TMS was delivered at different time windows (50–150 msec) after a brief 10-msec onset of face images, and participants reported the visibility and perceived emotional valence of faces. Interestingly, earlier TMS at ∼90 msec only reduced the face visibility irrespective of displayed expressions, but later TMS at ∼120 msec selectively disrupted the recognition of negative facial expressions, indicating the involvement of EVC in the processing of negative expressions at a later time window, possibly beyond the initial processing of fed-forward facial structure information. The observed TMS effect was further modulated by individuals' anxiety level. TMS at ∼110–120 msec disrupted the recognition of anger significantly more for those scoring relatively low in trait anxiety than the high scorers, suggesting that cognitive bias influences the processing of facial expressions in EVC. Taken together, it seems that EVC is involved in structural encoding of (at least) negative facial emotional valence, such as fear and anger, possibly under modulation from higher cortical areas.

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 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

Spatial Attentional Selection Modulates Early Visual Stimulus Processing Independently of Visual Alpha Modulations

2020 ◽  
Vol 30 (6) ◽  
pp. 3686-3703 ◽  
Author(s):  
C Gundlach ◽  
S Moratti ◽  
N Forschack ◽  
M M Müller
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Sensory Processing ◽  
Sensory Information ◽  
Gain Control ◽  
Relevant Information ◽  
Task Demands ◽  
Alpha Band ◽  
Stimulus Processing ◽  
Early Visual Cortex

Abstract The capacity-limited human brain is constantly confronted with a huge amount of sensory information. Selective attention is needed for biasing neural processing towards relevant information and consequently allows meaningful interaction with the environment. Activity in the alpha-band has been proposed to be related to top-down modulation of neural inhibition and could thus represent a viable candidate to control the priority of stimulus processing. It is, however, unknown whether modulations in the alpha-band directly relate to changes in the sensory gain control of the early visual cortex. Here, we used a spatial cueing paradigm while simultaneously measuring ongoing alpha-band oscillations and steady-state visual evoked potentials (SSVEPs) as a marker of continuous early sensory processing in the human visual cortex. Thereby, the effects of spatial attention for both of these signals and their potential interactions were assessed. As expected, spatial attention modulated both alpha-band and SSVEP responses. However, their modulations were independent of each other and the corresponding activity profiles differed across task demands. Thus, our results challenge the view that modulations of alpha-band activity represent a mechanism that directly alters or controls sensory gain. The potential role of alpha-band oscillations beyond sensory processing will be discussed in light of the present results.

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