scholarly journals Visual stress responses to static images are associated with symptoms of Persistent Postural Perceptual Dizziness (PPPD)

2021 ◽  
pp. 1-10
Author(s):  
Georgina Powell ◽  
Olivier Penacchio ◽  
Hannah Derry-Sumner ◽  
Simon K. Rushton ◽  
Deepak Rajenderkumar ◽  
...  
Keyword(s):  
Visual Cortex ◽  
General Population ◽  
Stress Responses ◽  
Visual Processing ◽  
Visual Signals ◽  
Natural Scene Statistics ◽  
Visual Discomfort ◽  
Cluttered Environments ◽  
Visual Stress ◽  
General Population Cohort

BACKGROUND: Images that deviate from natural scene statistics in terms of spatial frequency and orientation content can produce visual stress (also known as visual discomfort), especially for migraine sufferers. These images appear to over-activate the visual cortex. OBJECTIVE: To connect the literature on visual discomfort with a common chronic condition presenting in neuro-otology clinics known as persistent postural perceptual dizziness (PPPD). Sufferers experience dizziness when walking through highly cluttered environments or when watching moving stimuli. This is thought to arise from maladaptive interaction between vestibular and visual signals for balance. METHODS: We measured visual discomfort to stationary images in patients with PPPD (N = 30) and symptoms of PPPD in a large general population cohort (N = 1858) using the Visual Vertigo Analogue Scale (VVAS) and the Situational Characteristics Questionnaire (SCQ). RESULTS: We found that patients with PPPD, and individuals in the general population with more PPPD symptoms, report heightened visual discomfort to stationary images that deviate from natural spectra (patient comparison, F (1, 1865) = 29, p <  0.001; general population correlations, VVAS, rs (1387) = 0.46, p <  0.001; SCQ, rs (1387) = 0.39, p <  0.001). These findings were not explained by co-morbid migraine. Indeed, PPPD symptoms showed a significantly stronger relationship with visual discomfort than did migraine (VVAS, zH = 8.81, p <  0.001; SCQ, zH  = 6.29, p <  0.001). CONCLUSIONS: We speculate that atypical visual processing –perhaps due to a visual cortex more prone to over-activation –may predispose individuals to PPPD, possibly helping to explain why some patients with vestibular conditions develop PPPD and some do not.

scholarly journals Temporal evolution from retinal image size to perceived size in human visual cortex

2018 ◽  
Author(s):  
Juan Chen ◽  
Irene Sperandio ◽  
Molly J. Henry ◽  
Melvyn A Goodale
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Retinal Image ◽  
Feature Binding ◽  
Visual Signals ◽  
Viewing Distance ◽  
Size Constancy ◽  
Image Size ◽  
Subcortical Structures ◽  
Time Required

AbstractOur visual system affords a distance-invariant percept of object size by integrating retinal image size with viewing distance (size constancy). Single-unit studies with animals have shown that real changes in distance can modulate the firing rate of neurons in primary visual cortex and even subcortical structures, which raises an intriguing possibility that the required integration for size constancy may occur in the initial visual processing in V1 or even earlier. In humans, however, EEG and brain imaging studies have typically manipulated the apparent (not real) distance of stimuli using pictorial illusions, in which the cues to distance are sparse and not congruent. Here, we physically moved the monitor to different distances from the observer, a more ecologically valid paradigm that emulates what happens in everyday life. Using this paradigm in combination with electroencephalography (EEG), we were able for the first time to examine how the computation of size constancy unfolds in real time under real-world viewing conditions. We showed that even when all distance cues were available and congruent, size constancy took about 150 ms to emerge in the activity of visual cortex. The 150-ms interval exceeds the time required for the visual signals to reach V1, but is consistent with the time typically associated with later processing within V1 or recurrent processing from higher-level visual areas. Therefore, this finding provides unequivocal evidence that size constancy does not occur during the initial signal processing in V1 or earlier, but requires subsequent processing, just like any other feature binding mechanisms.

scholarly journals A neural correlate of visual discomfort from flicker

2020 ◽  
Author(s):  
Carlyn Patterson Gentile ◽  
Geoffrey K. Aguirre
Keyword(s):  
Visual Cortex ◽  
Neural Response ◽  
Cortical Activation ◽  
Uniform Field ◽  
Visual Aura ◽  
Visual Discomfort ◽  
Flickering Light ◽  
General Acceptance ◽  
Visual Stress ◽  
Visual Cortical

AbstractThe theory of “visual stress” holds that visual discomfort results from overactivation of the visual cortex. Despite general acceptance, there is a paucity of empirical data that confirm this relationship, particularly for discomfort from visual flicker. We examined the association between neural response and visual discomfort using flickering light of different temporal frequencies that separately targeted the magnocellular, parvocellular, and koniocellular post-receptoral pathways. Given prior work that has shown larger cortical responses to flickering light in people with migraine, we examined 10 headache free people and 10 migraineurs with visual aura. The stimulus was a uniform field, 50 degrees in diameter, that modulated with high-contrast flicker between 1.625 and 30 Hz. We asked subjects to rate their visual discomfort while we recorded steady state visually evoked potentials (ssVEP) from primary visual cortex. The peak temporal sensitivity ssVEP amplitude varied by post-receptoral pathway, and was consistent with the known properties of these visual channels. Notably, there was a direct, linear relationship between the amplitude of neural response to a stimulus and the degree of visual discomfort it evoked. No substantive differences between the migraine and control groups was found. These data link increased visual cortical activation with the experience of visual discomfort.

scholarly journals Alzheimer’s Disease Progressively Reduces Visual Functional Network Connectivity

2021 ◽  
pp. 1-14
Author(s):  
Jie Huang ◽  
Paul Beach ◽  
Andrea Bozoki ◽  
David C. Zhu
Keyword(s):  
Visual Cortex ◽  
Lower Order ◽  
Resting State ◽  
Visual Processing ◽  
Network Connectivity ◽  
Higher Order ◽  
Functional Network ◽  
Functional Networks ◽  
The Face ◽  
Processing Network

Background: Postmortem studies of brains with Alzheimer’s disease (AD) not only find amyloid-beta (Aβ) and neurofibrillary tangles (NFT) in the visual cortex, but also reveal temporally sequential changes in AD pathology from higher-order association areas to lower-order areas and then primary visual area (V1) with disease progression. Objective: This study investigated the effect of AD severity on visual functional network. Methods: Eight severe AD (SAD) patients, 11 mild/moderate AD (MAD), and 26 healthy senior (HS) controls undertook a resting-state fMRI (rs-fMRI) and a task fMRI of viewing face photos. A resting-state visual functional connectivity (FC) network and a face-evoked visual-processing network were identified for each group. Results: For the HS, the identified group-mean face-evoked visual-processing network in the ventral pathway started from V1 and ended within the fusiform gyrus. In contrast, the resting-state visual FC network was mainly confined within the visual cortex. AD disrupted these two functional networks in a similar severity dependent manner: the more severe the cognitive impairment, the greater reduction in network connectivity. For the face-evoked visual-processing network, MAD disrupted and reduced activation mainly in the higher-order visual association areas, with SAD further disrupting and reducing activation in the lower-order areas. Conclusion: These findings provide a functional corollary to the canonical view of the temporally sequential advancement of AD pathology through visual cortical areas. The association of the disruption of functional networks, especially the face-evoked visual-processing network, with AD severity suggests a potential predictor or biomarker of AD progression.

scholarly journals Endocannabinoid system mediates the association between gut-microbial diversity and anhedonia/amotivation in a general population cohort

2021 ◽  
Author(s):  
Amedeo Minichino ◽  
Matthew A. Jackson ◽  
Marta Francesconi ◽  
Claire J. Steves ◽  
Cristina Menni ◽  
...  
Keyword(s):  
General Population ◽  
Microbial Diversity ◽  
Gut Microbiome ◽  
Endocannabinoid System ◽  
Alpha Diversity ◽  
Serum Levels ◽  
Population Cohort ◽  
Random Intercept ◽  
General Population Cohort ◽  
Antidepressant Use

AbstractAnhedonia and amotivation are debilitating symptoms and represent unmet therapeutic needs in a range of clinical conditions. The gut-microbiome-endocannabinoid axis might represent a potential modifiable target for interventions. Based on results obtained from animal models, we tested the hypothesis that the endocannabinoid system mediates the association between gut-microbiome diversity and anhedonia/amotivation in a general population cohort. We used longitudinal data collected from 786 volunteer twins recruited as part the TwinsUK register. Our hypothesis was tested with a multilevel mediation model using family structure as random intercept. The model was set using alpha diversity (within-individual gut-microbial diversity) as predictor, serum and faecal levels of the endocannabinoid palmitoylethanolamide (PEA) as mediator, and anhedonia/amotivation as outcome. PEA is considered the endogenous equivalent of cannabidiol, with increased serum levels believed to have anti-depressive effects, while increased stool PEA levels, reflecting increased excretion, are believed to have opposite, detrimental, effects on mental health. We therefore expected that either reduced serum PEA or increased stool PEA would mediate the association between microbial diversity and anhedonia amotivation. Analyses were adjusted for obesity, diet, antidepressant use, sociodemographic and technical covariates. Data were imputed using multiple imputation by chained equations. Mean age was 65.2 ± 7.6; 93% of the sample were females. We found a direct, significant, association between alpha diversity and anhedonia/amotivation (β = −0.37; 95%CI: −0.71 to −0.03; P = 0.03). Faecal, but not serum, levels of the endocannabinoid palmitoylethanolamide (PEA) mediated this association: the indirect effect was significant (β = −0.13; 95%CI: −0.24 to −0.01; P = 0.03), as was the total effect (β = −0.38; 95%CI: −0.72 to −0.04; P = 0.03), whereas the direct effect of alpha diversity on anhedonia/amotivation was attenuated fully (β = −0.25; 95%CI: −0.60 to 0.09; P = 0.16). Our results suggest that gut-microbial diversity might contribute to anhedonia/amotivation via the endocannabinoid system. These findings shed light on the biological underpinnings of anhedonia/amotivation and suggest the gut microbiota-endocannabinoid axis as a promising therapeutic target in an area of unmet clinical need.

ApoE and vascular disease – resequencing and genotyping in a general population cohort

2021 ◽  
Vol 331 ◽  
pp. e53-e54
Author(s):  
K.L. Rasmussen ◽  
A. Tybjærg-Hansen ◽  
B.G. Nordestgaard ◽  
R. Frikke-Schmidt
Keyword(s):  
General Population ◽  
Vascular Disease ◽  
Population Cohort ◽  
General Population Cohort

fMRI-Guided TMS on Cortical Eye Fields: The Frontal But Not Intraparietal Eye Fields Regulate the Coupling Between Visuospatial Attention and Eye Movements

2009 ◽  
Vol 102 (6) ◽  
pp. 3469-3480 ◽  
Author(s):  
H. M. Van Ettinger-Veenstra ◽  
W. Huijbers ◽  
T. P. Gutteling ◽  
M. Vink ◽  
J. L. Kenemans ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Visual Processing ◽  
Discrimination Performance ◽  
Visual Image ◽  
Single Pulse ◽  
Visuospatial Attention ◽  
Movement Direction ◽  
Key Factor ◽  
And Shifts

It is well known that parts of a visual scene are prioritized for visual processing, depending on the current situation. How the CNS moves this focus of attention across the visual image is largely unknown, although there is substantial evidence that preparation of an action is a key factor. Our results support the view that direct corticocortical feedback connections from frontal oculomotor areas to the visual cortex are responsible for the coupling between eye movements and shifts of visuospatial attention. Functional magnetic resonance imaging (fMRI)–guided transcranial magnetic stimulation (TMS) was applied to the frontal eye fields (FEFs) and intraparietal sulcus (IPS). A single pulse was delivered 60, 30, or 0 ms before a discrimination target was presented at, or next to, the target of a saccade in preparation. Results showed that the known enhancement of discrimination performance specific to locations to which eye movements are being prepared was enhanced by early TMS on the FEF contralateral to eye movement direction, whereas TMS on the IPS resulted in a general performance increase. The current findings indicate that the FEF affects selective visual processing within the visual cortex itself through direct feedback projections.

scholarly journals Spatiotemporal profiles of visual processing with and without primary visual cortex

NeuroImage ◽  
2012 ◽  
Vol 63 (3) ◽  
pp. 1464-1477 ◽  
Author(s):  
Andreas A. Ioannides ◽  
Vahe Poghosyan ◽  
Lichan Liu ◽  
George A. Saridis ◽  
Marco Tamietto ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing
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