scholarly journals Contextual effects on binocular matching are evident in primary visual cortex

2019 ◽  
Author(s):  
Reuben Rideaux ◽  
Andrew E Welchman
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Neural Activity ◽  
Pattern Analysis ◽  
Brain Activity ◽  
Contextual Effects ◽  
Local Processing ◽  
Neuronal Responses ◽  
Global Context ◽  
Binocular Matching

ABSTRACTGlobal context can dramatically influence local visual perception. This phenomenon is well-documented for monocular features, e.g., the Kanizsa triangle. It has been demonstrated for binocular matching: the disambiguation of the Wallpaper Illusion (Brewster, 1844) via the luminance of the background (Anderson & Nakayama, 1994). For monocular features, there is evidence that global context can influence neuronal responses as early as V1 (Muckli et al., 2015). However, for binocular matching, the activity in this area of the visual cortex is thought to represent local processing, suggesting that the influence of global context may occur at later stages of cortical processing. Here we sought to test if binocular matching is influenced by contextual effects in V1, using fMRI to measure brain activity while participants viewed perceptually ambiguous “wallpaper” stereograms whose depth was disambiguated by the luminance of the surrounding region. We localized voxels in V1 corresponding to the ambiguous region of the pattern, i.e., where the signal received from the eyes was not predictive of depth, and despite the ambiguity of the input signal, using multi-voxel pattern analysis we were able to reliably decode perceived (near/far) depth from the activity of these voxels. These findings indicate that stereoscopic related neural activity is influenced by global context as early as V1.

scholarly journals The essential role of feedback processing for figure-ground perception in mice

2018 ◽  
Author(s):  
Lisa Kirchberger ◽  
Sreedeep Mukherjee ◽  
Ulf H. Schnabel ◽  
Enny H. van Beest ◽  
Areg Barsegyan ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Essential Role ◽  
Pyramidal Cells ◽  
Neuronal Responses ◽  
Feedback Processing ◽  
Visual Areas ◽  
Higher Visual Areas ◽  
Delayed Phase

AbstractThe segregation of figures from the background is an important step in visual perception. In primary visual cortex, figures evoke stronger activity than backgrounds during a delayed phase of the neuronal responses, but it is unknown how this figure-ground modulation (FGM) arises and whether it is necessary for perception. Here we show, using optogenetic silencing in mice, that the delayed V1 response phase is necessary for figure-ground segregation. Neurons in higher visual areas also exhibit FGM and optogenetic silencing of higher areas reduced FGM in V1. In V1, figures elicited higher activity of vasoactive intestinal peptide-expressing (VIP) interneurons than the background, whereas figures suppressed somatostatin-positive interneurons, resulting in an increased activation of pyramidal cells. Optogenetic silencing of VIP neurons reduced FGM in V1, indicating that disinhibitory circuits contribute to FGM. Our results provide new insight in how lower and higher areas of the visual cortex interact to shape visual perception.

scholarly journals The essential role of recurrent processing for figure-ground perception in mice

2021 ◽  
Vol 7 (27) ◽  
pp. eabe1833
Author(s):  
Lisa Kirchberger ◽  
Sreedeep Mukherjee ◽  
Ulf H. Schnabel ◽  
Enny H. van Beest ◽  
Areg Barsegyan ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Pyramidal Cells ◽  
Neuronal Responses ◽  
Visual Areas ◽  
Recurrent Processing ◽  
Higher Visual Areas ◽  
Delayed Phase ◽  
Insight Into

The segregation of figures from the background is an important step in visual perception. In primary visual cortex, figures evoke stronger activity than backgrounds during a delayed phase of the neuronal responses, but it is unknown how this figure-ground modulation (FGM) arises and whether it is necessary for perception. Here, we show, using optogenetic silencing in mice, that the delayed V1 response phase is necessary for figure-ground segregation. Neurons in higher visual areas also exhibit FGM and optogenetic silencing of higher areas reduced FGM in V1. In V1, figures elicited higher activity of vasoactive intestinal peptide–expressing (VIP) interneurons than the background, whereas figures suppressed somatostatin-positive interneurons, resulting in an increased activation of pyramidal cells. Optogenetic silencing of VIP neurons reduced FGM in V1, indicating that disinhibitory circuits contribute to FGM. Our results provide insight into how lower and higher areas of the visual cortex interact to shape visual perception.

scholarly journals Metacognition facilitates the exploitation of unconscious brain states

2019 ◽  
Author(s):  
Aurelio Cortese ◽  
Hakwan Lau ◽  
Mitsuo Kawato
Keyword(s):  
Reinforcement Learning ◽  
Neural Activity ◽  
Pattern Analysis ◽  
Brain Activity ◽  
High Dimensional ◽  
Multivoxel Pattern Analysis ◽  
Brain States ◽  
Optimal Action ◽  
The Brain ◽  
Do So

AbstractCan humans be trained to make strategic use of unconscious representations in their own brains? We investigated how one can derive reward-maximizing choices from latent high-dimensional information represented stochastically in neural activity. In a novel decision-making task, reinforcement learning contingencies were defined in real-time by fMRI multivoxel pattern analysis; optimal action policies thereby depended on multidimensional brain activity that took place below the threshold of consciousness. We found that subjects could solve the task, when their reinforcement learning processes were boosted by implicit metacognition to estimate the relevant brain states. With these results we identified a frontal-striatal mechanism by which the brain can untangle tasks of great dimensionality, and can do so much more flexibly than current artificial intelligence.

scholarly journals Photorealistic Reconstruction of Visual Texture From EEG Signals

2021 ◽  
Vol 15 ◽  
Author(s):  
Suguru Wakita ◽  
Taiki Orima ◽  
Isamu Motoyoshi
Keyword(s):  
Visual Cortex ◽  
Spatial Resolution ◽  
Neural Activity ◽  
High Spatial Resolution ◽  
Brain Activity ◽  
Spatial Layout ◽  
Eeg Signals ◽  
Visual Texture ◽  
Sensory Stimuli ◽  
Neural Data

Recent advances in brain decoding have made it possible to classify image categories based on neural activity. Increasing numbers of studies have further attempted to reconstruct the image itself. However, because images of objects and scenes inherently involve spatial layout information, the reconstruction usually requires retinotopically organized neural data with high spatial resolution, such as fMRI signals. In contrast, spatial layout does not matter in the perception of “texture,” which is known to be represented as spatially global image statistics in the visual cortex. This property of “texture” enables us to reconstruct the perceived image from EEG signals, which have a low spatial resolution. Here, we propose an MVAE-based approach for reconstructing texture images from visual evoked potentials measured from observers viewing natural textures such as the textures of various surfaces and object ensembles. This approach allowed us to reconstruct images that perceptually resemble the original textures with a photographic appearance. The present approach can be used as a method for decoding the highly detailed “impression” of sensory stimuli from brain activity.

scholarly journals Top-down control of visual cortex by the frontal eye fields through oscillatory realignment

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Domenica Veniero ◽  
Joachim Gross ◽  
Stephanie Morand ◽  
Felix Duecker ◽  
Alexander T. Sack ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Visual Perception ◽  
Magnetic Stimulation ◽  
Single Pulse ◽  
Frontal Eye Fields ◽  
Phase Reset ◽  
Top Down ◽  
Visual Areas ◽  
Beta Frequency

AbstractVoluntary allocation of visual attention is controlled by top-down signals generated within the Frontal Eye Fields (FEFs) that can change the excitability of lower-level visual areas. However, the mechanism through which this control is achieved remains elusive. Here, we emulated the generation of an attentional signal using single-pulse transcranial magnetic stimulation to activate the FEFs and tracked its consequences over the visual cortex. First, we documented changes to brain oscillations using electroencephalography and found evidence for a phase reset over occipital sites at beta frequency. We then probed for perceptual consequences of this top-down triggered phase reset and assessed its anatomical specificity. We show that FEF activation leads to cyclic modulation of visual perception and extrastriate but not primary visual cortex excitability, again at beta frequency. We conclude that top-down signals originating in FEF causally shape visual cortex activity and perception through mechanisms of oscillatory realignment.

Sign in / Sign up

Export Citation Format

Share Document