scholarly journals Fear conditioning prompts sparser representations of conditioned threat in primary visual cortex

2020 ◽  
Author(s):  
Siyang Yin ◽  
Ke Bo ◽  
Yuelu Liu ◽  
Nina Thigpen ◽  
Andreas Keil ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Fear Conditioning ◽  
Primary Visual Cortex ◽  
Neural Mechanism ◽  
Rate Of Change ◽  
Aversive Learning ◽  
Alpha Oscillations ◽  
Sensory Responses ◽  
Human Participants ◽  
The Right

AbstractRepeated exposure to threatening stimuli alters sensory responses. We investigated the underlying neural mechanism by recording simultaneous EEG-fMRI from human participants viewing oriented gratings during Pavlovian fear conditioning. In acquisition, one grating (the CS+) was paired with a noxious noise, the unconditioned stimulus (US). The other grating (CS-) was never paired with US. In habituation, which preceded acquisition, and in final extinction, the same two gratings were presented without the US. Using fMRI-BOLD multivoxel patterns in primary visual cortex during habituation as reference, we found that during acquisition, aversive learning selectively prompted systematic changes in multivoxel patterns evoked by the CS+. Specifically, CS+ evoked voxel patterns in V1 became sparser as aversive learning progressed, and the sparse pattern was preserved in extinction. Concomitant with the voxel pattern changes, occipital alpha oscillations were increasingly more desynchronized during CS+ (but not CS-) trials. Across acquisition trials, the rate of change in CS+-related alpha desynchronization was correlated with the rate of change in multivoxel pattern representations of the CS+. Furthermore, alpha oscillations co-varied with BOLD in the right temporal-parietal junction, but not with BOLD in the amygdala. Thus, fear conditioning prompts persistent sparsification of threat cue representations, likely mediated by attention-related mechanisms.

scholarly journals Fear conditioning prompts sparser representations of conditioned threat in primary visual cortex

2020 ◽  
Vol 15 (9) ◽  
pp. 950-964
Author(s):  
Siyang Yin ◽  
Ke Bo ◽  
Yuelu Liu ◽  
Nina Thigpen ◽  
Andreas Keil ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Fear Conditioning ◽  
Primary Visual Cortex ◽  
Neural Mechanism ◽  
Blood Oxygen Level Dependent ◽  
Rate Of Change ◽  
Aversive Learning ◽  
Blood Oxygen Level ◽  
Alpha Oscillations ◽  
Sensory Responses

Abstract Repeated exposure to threatening stimuli alters sensory responses. We investigated the underlying neural mechanism by re-analyzing previously published simultaneous electroencephalogram-functional magnetic resonance imaging (EEG-fMRI) data from humans viewing oriented gratings during Pavlovian fear conditioning. In acquisition, one grating (CS+) was paired with a noxious noise, the unconditioned stimulus (US). The other grating (CS-) was never paired with the US. In habituation, which preceded acquisition, and in extinction, the same two gratings were presented without US. Using fMRI multivoxel patterns in primary visual cortex during habituation as reference, we found that during acquisition, aversive learning selectively prompted systematic changes in multivoxel patterns evoked by CS+. Specifically, CS+ evoked voxel patterns in V1 became sparser as aversive learning progressed, and the sparsified pattern appeared to be preserved in extinction. Concomitant with the voxel pattern changes, occipital alpha oscillations were increasingly more desynchronized during CS+ (but not CS-) trials. Across acquisition trials, the rate of change in CS+-related alpha desynchronization was correlated with the rate of change in multivoxel pattern representations of CS+. Furthermore, alpha oscillations co-varied with blood-oxygen-level-dependent (BOLD) data in the ventral attention network, but not with BOLD in the amygdala. Thus, fear conditioning prompts persistent sparsification of voxel patterns evoked by threat, likely mediated by attention-related mechanisms

scholarly journals Disparity processing in primary visual cortex

2016 ◽  
Vol 371 (1697) ◽  
pp. 20150255 ◽  
Author(s):  
Sid Henriksen ◽  
Seiji Tanabe ◽  
Bruce Cumming
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Striate Cortex ◽  
Three Dimensional ◽  
Empirical Support ◽  
Energy Model ◽  
Correspondence Problem ◽  
Stereo Correspondence ◽  
V1 Neurons ◽  
The Right

The first step in binocular stereopsis is to match features on the left retina with the correct features on the right retina, discarding ‘false’ matches. The physiological processing of these signals starts in the primary visual cortex, where the binocular energy model has been a powerful framework for understanding the underlying computation. For this reason, it is often used when thinking about how binocular matching might be performed beyond striate cortex. But this step depends critically on the accuracy of the model, and real V1 neurons show several properties that suggest they may be less sensitive to false matches than the energy model predicts. Several recent studies provide empirical support for an extended version of the energy model, in which the same principles are used, but the responses of single neurons are described as the sum of several subunits, each of which follows the principles of the energy model. These studies have significantly improved our understanding of the role played by striate cortex in the stereo correspondence problem. This article is part of the themed issue ‘Vision in our three-dimensional world’.

The Rotating Tilted Lines Illusion

2017 ◽  
Author(s):  
Simone Gori
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Stimulus Pattern ◽  
Motion Processing ◽  
White Background ◽  
Radial Expansion ◽  
Circular Pattern ◽  
Counterclockwise Direction ◽  
The Right ◽  
Rotatory Motion

This chapter describes the Rotating-Tilted-Lines illusion , which is a new motion illusion that arises in a circular pattern composed by black, radial lines tilted to the right and presented on a white background. When one approaches the stimulus pattern, the radial lines appear to rotate in the counterclockwise direction, whereas when one recedes from it, they appear to rotate clockwise. It is the simplest pattern able to elicit illusory rotatory motion in presence of physical radial expansion. This surprising misperception of motion seems to be a result of the competition between two motion processing units in the primary visual cortex (V1, V5)

Numerical relationship between neurons in the lateral geniculate nucleus and primary visual cortex in macaque monkeys

1996 ◽  
Vol 13 (3) ◽  
pp. 585-590 ◽  
Author(s):  
Ivan Suner ◽  
Pasko Rakic
Keyword(s):  
Visual Cortex ◽  
Lateral Geniculate Nucleus ◽  
Primary Visual Cortex ◽  
Rhesus Monkeys ◽  
Three Dimensional ◽  
Area 17 ◽  
Counting Method ◽  
Lateral Geniculate ◽  
Cortex Area ◽  
The Right

AbstractWe examined the numerical correlation between total populations of neurons in the lateral geniculate nucleus (LGN) and the primary visual cortex (area 17 of Brodmann) in ten cerebral hemispheres of five normal rhesus monkeys using an unbiased three-dimensional counting method. There were 1.4 ± 0.2 million and 341 ±54 million neurons in the LGN and area 17, respectively. In each animal, a larger LGN on one side was in register with a larger area 17 of the cortex on the same side. Furthermore, asymmetry in the number of neurons in both the LGN and area 17 favored the right side. However, because of small variations across subjects, correlation between the total neuron number in LGN and area 17 was weak (r = 0.29). These results suggest that the final numbers of neurons in these visual centers may be established independently or by multiple factors controlling elimination of initially overproduced neurons.

scholarly journals The Role of Spared Calcarine Cortex and Lateral Occipital Cortex in the Responses of Human Hemianopes to Visual Motion

2004 ◽  
Vol 16 (2) ◽  
pp. 204-218 ◽  
Author(s):  
Antony B. Morland ◽  
Sandra Lê ◽  
Erin Carroll ◽  
Michael B. Hoffmann ◽  
Alidz Pambakian
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion ◽  
Neural Mechanism ◽  
Visual Pathways ◽  
The Other ◽  
Visual Response ◽  
Visual Responses ◽  
Behavioral Experiments ◽  
Residual Vision

Some patients, who are rendered perimetrically blind in one hemifield by cortical lesions, nevertheless exhibit residual visual capacities within their field defects. The neural mechanism that mediates the residual visual responses has remained the topic of considerable debate. One explanation posits the subcortical visual pathways that bypass the primary visual cortex and innervate the extrastriate visual areas as the substrate that underlies the residual vision. The other explanation is that small islands of the primary visual cortex remain intact and provide the signals for residual vision. We have performed behavioral and functional magnetic resonance imaging experiments to investigate the validity of the two explanations of residual vision. Our behavioral experiments indicated that of the seven hemianopes tested, two had the ability to discriminate the direction of a drifting grating. This residual visual response was shown with fMRI to be the result of spared islands of calcarine cortical activity in one of the hemianopes, whereas only lateral occipital activity was documented in the other patient. These results indicate that the underlying neural correlates of residual vision can vary between patients. Moreover, our study emphasizes the necessity of ruling out the presence of islands of preserved function and primary visual cortex before assigning residual visual capacities to the properties of visual pathways that bypass the primary visual cortex.

scholarly journals Direction-selective motion discrimination by traveling waves in visual cortex

2020 ◽  
Author(s):  
Stewart Heitmann ◽  
G. Bard Ermentrout
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Primary Visual Cortex ◽  
Visual Stimulus ◽  
Traveling Waves ◽  
Neural Activity ◽  
Time Delays ◽  
Neural Mechanism ◽  
Neural Responses ◽  
Transmission Delays

AbstractThe majority of neurons in primary visual cortex respond selectively to bars of light that have a specific orientation and move in a specific direction. The spatial and temporal responses of such neurons are non-separable. How neurons accomplish that computational feat without resort to explicit time delays is unknown. We propose a novel neural mechanism whereby visual cortex computes non-separable responses by generating endogenous traveling waves of neural activity that resonate with the space-time signature of the visual stimulus. The spatiotemporal characteristics of the response are defined by the local topology of excitatory and inhibitory lateral connections in the cortex. We simulated the interaction between endogenous traveling waves and the visual stimulus using spatially distributed populations of excitatory and inhibitory neurons with Wilson-Cowan dynamics and inhibitory-surround coupling. Our model reliably detected visual gratings that moved with a given speed and direction provided that we incorporated neural competition to suppress false motion signals in the opposite direction. The findings suggest that endogenous traveling waves in visual cortex can impart direction-selectivity on neural responses without resort to explicit time delays. They also suggest a functional role for motion opponency in eliminating false motion signals.Author summaryIt is well established that the so-called ‘simple cells’ of the primary visual cortex respond preferentially to oriented bars of light that move across the visual field with a particular speed and direction. The spatiotemporal responses of such neurons are said to be non-separable because they cannot be constructed from independent spatial and temporal neural mechanisms. Contemporary theories of how neurons compute non-separable responses typically rely on finely tuned transmission delays between signals from disparate regions of the visual field. However the existence of such delays is controversial. We propose an alternative neural mechanism for computing non-separable responses that does not require transmission delays. It instead relies on the predisposition of the cortical tissue to spontaneously generate spatiotemporal waves of neural activity that travel with a particular speed and direction. We propose that the endogenous wave activity resonates with the visual stimulus to elicit direction-selective neural responses to visual motion. We demonstrate the principle in computer models and show that competition between opposing neurons robustly enhances their ability to discriminate between visual gratings that move in opposite directions.

scholarly journals Intrinsic functional connectivity alterations of the primary visual cortex in patients with proliferative diabetic retinopathy: a seed-based resting-state fMRI study

2020 ◽  
Vol 11 ◽  
pp. 204201882096029
Author(s):  
Yao Yu ◽  
Dong-Yi Lan ◽  
Li-Ying Tang ◽  
Ting Su ◽  
Biao Li ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Visual Cortex ◽  
Functional Connectivity ◽  
Primary Visual Cortex ◽  
Proliferative Diabetic Retinopathy ◽  
Resting State ◽  
Visual Information ◽  
Brain Regions ◽  
Intrinsic Functional Connectivity ◽  
The Right

Purpose: In this study, we aimed to investigate the differences in the intrinsic functional connectivity (iFC) of the primary visual cortex (V1), based on resting-state functional magnetic resonance imaging (rs-fMRI), between patients with proliferative diabetic retinopathy (PDR) and healthy controls (HCs). Methods: In total, 26 patients (12 males, 14 females) with PDR and 26 HCs (12 males, 14 females), matched for sex, age, and education status, were enrolled in the study. All individuals underwent rs-fMRI scans. We acquired iFC maps and compared the differences between PDR patients and the HCs. Results: The PDR group had significantly increased FC between the left V1 and the right middle frontal gyrus (RMFG), and significantly reduced FC between the left V1 and the cuneus/calcarine/precuneus. In addition, the PDR patients had significantly increased FC between the right V1 and the right superior frontal gyrus (RSFG), and significantly reduced FC between the right V1 and the cuneus/calcarine/precuneus. The individual areas under the curve (AUCs) of FC values for the left V1 were as follows: RMFG (0.871, p < 0.001) and the cuneus/calcarine/precuneus (0.914, p < 0.001), while the AUCs of FC values for the right V1 were as follows: RSFG (0.895, p < 0.001) and the cuneus/calcarine/precuneus (0.918, p < 0.001). Conclusions: The results demonstrated that, in PDR patients, altered iFC in distinct brain regions, including regions related to visual information processing and cognition. Considering the rise in the diabetes mellitus incidence rate and the consequences of PDR, the results could provide promising clues for exploring the neural mechanisms related to PDR and possible approaches for the early identification of PDR.

scholarly journals Sensory readout accounts for adaptation

2021 ◽  
Author(s):  
Timothy C Sheehan ◽  
John T Serences
Keyword(s):  
Visual Cortex ◽  
Temporal Structure ◽  
Orientation Discrimination ◽  
Response Patterns ◽  
Serial Dependence ◽  
Stimulus Response ◽  
Behavioral Studies ◽  
Sensory Responses ◽  
Human Participants ◽  
Sensory Encoding

Sensory responses and behavior are strongly shaped by stimulus history. For instance, perceptual reports are sometimes biased towards previously viewed stimuli (serial dependence). Previous behavioral studies suggest that serial dependence is implemented via modulations in visual cortex, but neural evidence is lacking. We recorded fMRI responses while human participants performed a delayed orientation discrimination task. While behavioral reports were attracted to the previous stimulus, response patterns in sensory areas were repelled. We reconciled these opposing biases using a model where both sensory encoding and readout are shaped by stimulus history. Neural adaptation reduces redundancy at encoding and leads to the repulsive biases that we observed in visual cortex. Serial dependence is not implemented in visual cortex but rather by readout mechanisms that account for adaptation during encoding. The model suggests the visual system improves efficiency via adaptation while still optimizing behavioral readout based on the temporal structure of natural stimuli.

scholarly journals Vision AfterEarly-OnsetLesions of the Occipital Cortex: II. Physiological Studies

2002 ◽  
Vol 9 (1) ◽  
pp. 27-40 ◽  
Author(s):  
M. G. Knyazeva ◽  
P. Maeder ◽  
D. C. Kiper ◽  
T. Deonna ◽  
G. M. Innocenti
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Functional Recovery ◽  
Right Hemisphere ◽  
Occipital Cortex ◽  
Quantitative Eeg ◽  
Functional Maturation ◽  
Consistent Increase ◽  
The Right

In one of two patients (MS and FJ) with bilateral, early-onset lesion of the primary visual cortex, Kiper et al. (2002) observed a considerable degree of functional recovery. To clarify the physiological mechanisms involved in the recovery, we used fMRI and quantitative EEG to study both patients. The fMRI investigations indicated that in both patients, isolated islands of the primary visual cortex are functioning, in the right hemisphere in MS and in the left in FJ. The functional recovery observed in MS roughly correlated with the functional maturation of interhemispheric connections and might reflect the role of corticocortical connectivity in visual perception. The functionality of interhemispheric connections was assessed by analyzing the changes in occipital inter-hemispheric coherence of EEG signals (ICoh) evoked by moving gratings. In the patient MS, this ICoh response was present at 7:11 y and was more mature at 9:2 y. In the more visually mpaired patient, FJ, a consistent increase in ICoh to visual stimuli could not be obtained, possibly because of the later occurrence of the lesion.

scholarly journals A Signal-Processing Neural Model Based on Biological Retina

Electronics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 35
Author(s):  
Hui Wei ◽  
Luping Wang ◽  
Shanshan Wang ◽  
Yuxiang Jiang ◽  
Jingmeng Li
Keyword(s):  
Signal Processing ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Neural Mechanism ◽  
Neural Model ◽  
Analytical Geometry ◽  
Neural Architecture ◽  
Signal Features

Image signal processing has considerable value in artificial intelligence. However, due to the diverse disturbance (e.g., color, noise), the image signal processing, especially the representation of the signal, remains a big challenge. In the human visual system, it has been justified that simple cells in the primary visual cortex are obviously sensitive to vision signals with partial orientation features. In other words, the image signals are extracted and described along the pathway of visual processing. Inspired by this neural mechanism of the primary visual cortex, it is possible to build an image signal-processing model as the neural architecture. In this paper, we presented a method to process the image signal involving a multitude of disturbance. For image signals, we first extracted 4 rivalry pathways via the projection of color. Secondly, we designed an algorithm in which the computing process of the stimulus with partial orientation features can be altered into a process of analytical geometry, resulting in that the signals with orientation features can be extracted and characterized. Finally, through the integration of characterizations from the 4 different rivalry pathways, the image signals can be effectively interpreted and reconstructed. Instead of data-driven methods, the presented approach requires no prior training. With the use of geometric inferences, the method tends to be interpreted and applied in the signal processor. The extraction and integration of rivalry pathways of different colors allow the method to be effective and robust to the signals with the image noise and disturbance of colors. Experimental results showed that the approach can extract and describing the image signal with diverse disturbance. Based on the characterization of the image signal, it is possible to reconstruct signal features which can effectively represent the important information from the original image signal.

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