scholarly journals Structural and Functional Connectivity of Visual Cortex in Schizophrenia and Bipolar Disorder: A Graph-Theoretic Analysis

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Eric A Reavis ◽  
Junghee Lee ◽  
Lori L Altshuler ◽  
Mark S Cohen ◽  
Stephen A Engel ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Visual Cortex ◽  
Functional Connectivity ◽  
Visual System ◽  
Visual Processing ◽  
Functional Outcomes ◽  
Brain Atlas ◽  
Imaging Data ◽  
Significant Group ◽  
Graph Theoretic

Abstract Visual processing abnormalities in schizophrenia (SZ) are poorly understood, yet predict functional outcomes in the disorder. Bipolar disorder (BD) may involve similar visual processing deficits. Converging evidence suggests that visual processing may be relatively normal at early stages of visual processing such as early visual cortex (EVC), but that processing abnormalities may become more pronounced by mid-level visual areas such as lateral occipital cortex (LO). However, little is known about the connectivity of the visual system in SZ and BD. If the flow of information to, from, or within the visual system is disrupted by reduced connectivity, this could help to explain perceptual deficits. In the present study, we performed a targeted analysis of the structural and functional connectivity of the visual system using graph-theoretic metrics in a sample of 48 SZ, 46 BD, and 47 control participants. Specifically, we calculated parallel measures of local efficiency for EVC and LO from both diffusion weighted imaging data (structural) and resting-state (functional) imaging data. We found no structural connectivity differences between the groups. However, there was a significant group difference in functional connectivity and a significant group-by-region interaction driven by reduced LO connectivity in SZ relative to HC, whereas BD was approximately intermediate to the other 2 groups. We replicated this pattern of results using a different brain atlas. These findings support and extend theoretical models of perceptual dysfunction in SZ, providing a framework for further investigation of visual deficits linked to functional outcomes in SZ and related disorders.

scholarly journals Graph theory analysis of whole brain functional connectivity to assess disturbances associated with suicide attempts in bipolar disorder

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Anjali Sankar ◽  
Dustin Scheinost ◽  
Danielle A. Goldman ◽  
Rebecca Drachman ◽  
Lejla Colic ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Suicidal Ideation ◽  
Functional Connectivity ◽  
Suicide Risk ◽  
Suicide Attempts ◽  
Imaging Data ◽  
Significant Group ◽  
Whole Brain ◽  
Graph Theoretical Approach ◽  
Suicide Behaviors

AbstractBrain targets to lower the high risk of suicide in Bipolar Disorder (BD) are needed. Neuroimaging studies employing analyses dependent on regional assumptions could miss hubs of dysfunction critical to the pathophysiology of suicide behaviors and their prevention. This study applied intrinsic connectivity distribution (ICD), a whole brain graph‐theoretical approach, to identify hubs of functional connectivity (FC) disturbances associated with suicide attempts in BD. ICD, from functional magnetic resonance imaging data acquired while performing a task involving implicit emotion regulation processes important in BD and suicide behaviors, was compared across 40 adults with BD with prior suicide attempts (SAs), 49 with BD with no prior attempts (NSAs) and 51 healthy volunteers (HVs). Areas of significant group differences were used as seeds to identify regional FC differences and explore associations with suicide risk-related measures. ICD was significantly lower in SAs than in NSAs and HVs in bilateral ventromedial prefrontal cortex (vmPFC) and right anterior insula (RaIns). Seed connectivity revealed altered FC from vmPFC to bilateral anteromedial orbitofrontal cortex, left ventrolateral PFC (vlPFC) and cerebellum, and from RaIns to right vlPFC and temporopolar cortices. VmPFC and RaIns ICD were negatively associated with suicidal ideation severity, and vmPFC ICD with hopelessness and attempt lethality severity. The findings suggest that SAs with BD have vmPFC and RaIns hubs of dysfunction associated with altered FC to other ventral frontal, temporopolar and cerebellar cortices, and with suicidal ideation, hopelessness, and attempt lethality. These hubs may be targets for novel therapeutics to reduce suicide risk in BD.

scholarly journals Visual search for object categories is predicted by the representational architecture of high-level visual cortex

2017 ◽  
Vol 117 (1) ◽  
pp. 388-402 ◽  
Author(s):  
Michael A. Cohen ◽  
George A. Alvarez ◽  
Ken Nakayama ◽  
Talia Konkle
Keyword(s):  
Visual Cortex ◽  
Visual Search ◽  
Visual System ◽  
Visual Processing ◽  
Search Task ◽  
Visual Search Task ◽  
Visual Object ◽  
Neural Responses ◽  
Object Categories ◽  
High Level

Visual search is a ubiquitous visual behavior, and efficient search is essential for survival. Different cognitive models have explained the speed and accuracy of search based either on the dynamics of attention or on similarity of item representations. Here, we examined the extent to which performance on a visual search task can be predicted from the stable representational architecture of the visual system, independent of attentional dynamics. Participants performed a visual search task with 28 conditions reflecting different pairs of categories (e.g., searching for a face among cars, body among hammers, etc.). The time it took participants to find the target item varied as a function of category combination. In a separate group of participants, we measured the neural responses to these object categories when items were presented in isolation. Using representational similarity analysis, we then examined whether the similarity of neural responses across different subdivisions of the visual system had the requisite structure needed to predict visual search performance. Overall, we found strong brain/behavior correlations across most of the higher-level visual system, including both the ventral and dorsal pathways when considering both macroscale sectors as well as smaller mesoscale regions. These results suggest that visual search for real-world object categories is well predicted by the stable, task-independent architecture of the visual system. NEW & NOTEWORTHY Here, we ask which neural regions have neural response patterns that correlate with behavioral performance in a visual processing task. We found that the representational structure across all of high-level visual cortex has the requisite structure to predict behavior. Furthermore, when directly comparing different neural regions, we found that they all had highly similar category-level representational structures. These results point to a ubiquitous and uniform representational structure in high-level visual cortex underlying visual object processing.

scholarly journals Νευροχημική και νευροβιολογική μελέτη της επίδρασης του εμπλουτισμένου περιβάλλοντος στη φυσιολογία της όρασης των επιμύων

2013 ◽  
Author(s):  
Δημήτριος Μπεσίνης
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Visual Processing ◽  
Environmental Enrichment ◽  
Optic Chiasm ◽  
Enriched Environment ◽  
Female Rats ◽  
Male And Female ◽  
Serotonergic Activity

Environmental enrichment refers to the changes that happen in the centralnervous system of an animal which lives in bigger cages than typical labcages, with tunnels, running wheels and two floors. The purpose of this studywas to investigate the effects of environmental enrichment in the physiology ofthe visual system as well as in regions which contribute to the elaboration ofthe visual information. Sex differences were also taken into consideration. Ourgoal was achieved with the observation of developmental clues and the studyof behavioral and neurochemical parameters in male and female Wistar rats.The results of our study show that environmental enrichment accelerates theeye-opening procedure. Early enrichment decreases mobility duringprepuberty, without affecting it during adult life. On the contrary introducingenvironmental enrichment during adulthood increases mobility in both sexes.Early and late environmental enrichment also increases attention of maleadult animals. At the same time increased environmental stimuli give theability to male and female rats to identify more easily a newly presentedobject. It seems that enriched environment affects visual processing mostly infemale animals.For the first time in the present study we identified the involvement ofhistamine in the development and adaptation of the visual system. Histaminelevels in the optic chiasm but not the visual cortex are decreased in bothsexes through lifespan development. Histamine levels are also double in theoptic chiasm of males compared to females at all ages studied. Similar sexdifference was observed only during prepuberty in the visual cortex. Earlyenrichment decreased histamine levels in the optic chiasm of both sexesduring prepuberty, maintaining the sex difference observed in the basal levels.Histamine levels were comparable from prepuberty to adulthood upon rearing in richer environment. In contrast, introducing the enriched environment modelin adult animals increased histamine levels in the optic chiasm of female rats,indicating a sex difference in the adaptation of the central histaminergicsystem which interacts with the visual system.Neurochemical changes were also noted in the dopaminergic system of theretina and the visual cortex. Early enrichment does not affect dopaminergicactivity of the retina during development. On the contrary it inducedneurochemical changes in the adult female retina underlying adaptation inhigh illumination conditions, whereas late enrichment induced the sameneurochemical alterations in the retina of both male and female rats.Moreover the present study provides evidence that dopamine in not involvedin the development of the visual cortex, but is implicated in the function of thevisual cortex as well as visual processing.Enriched environment also ineracts with the serotonergic system of the retina.Serotonergic activity is increased by enhanced environmental stimuli possiblyleading to increased endogenous neuroprotection of the photosensitive layerof the eye. The present study also clarifies the interplay of plasticity andserotonergic activity in the visual cortex. Serotonergic activity is decreasedfrom prepuberty to adulthood. It seems that there is a range of serotonergicactivity within which it promotes plasticity. If serotonergic activity is increasedor decreased out of this range then plasticity is inhibited. It is also importantthat apart from the increase in neurotrophins levels observed in the visualcortex after environmental enrichment, plasticity is also facilitated throughserotonergic activity.Another important finding is that enriched environment alters neurochemistryin the prefrontal cortex which is important for stress response. For the firsttime in the present study we provide evidence that enriched environment(either from birth or during adulthood), leads to sex dependent activation ofstress mechanisms. The changes observed in the serotonergic activity of theprefrontal cortex are also sex dependent. It is possible that early environmental enrichment reduces the vulnerability to depression in adultfemale rats through increased serotonergic activity in the prefrontal cortex.Serotonergic activity of the hippocampus is also influenced by environmentalstimuli. Environmental enrichment either from birth or during adulthood affectsserotonergic activity of the hippocampus only in female animals. Thesechanges are capable of either to increase vulnerability to depression orattribute therapeutical advantages against this disease.In the present study the neurochemical profile of visual tissues in differentperiods of lifespan development and the neurochemical changesaccompanying the beneficial effects of environmental enrichment wereidentified. The results of the present raise the question of the role of histaminereceptors in visual perception and visual processing. The above resultsemphasize how crucial it is to map all the regions of the brain which interactwith the visual system and are involved in the function of vision. In additionthe present study shows how important it is to elucidate the role of enrichedenvironment in learning-memory and in the regulation of the sentiments.

scholarly journals Auditory Target Detection Enhances Visual Processing and Hippocampal Functional Connectivity

2020 ◽  
Author(s):  
Roy Moyal ◽  
Hamid B. Turker ◽  
Wen-Ming Luh ◽  
Khena M. Swallow
Keyword(s):  
Visual Cortex ◽  
Functional Connectivity ◽  
Locus Coeruleus ◽  
Target Detection ◽  
Visual Processing ◽  
Target Tone ◽  
Auditory Target ◽  
Parahippocampal Gyrus ◽  
Subcortical Regions ◽  
Selection Of

AbstractThough dividing one’s attention between two input streams typically impairs performance, detecting a behaviorally relevant stimulus can sometimes enhance the encoding of task-irrelevant information presented at the same time. Previous research has shown that temporal selection of this kind boosts visual cortical activity and incidental memory. An important and yet unanswered question is whether such effects are reflected in processing quality and functional connectivity in visual regions and the hippocampus. In this fMRI study, participants were asked to memorize a stream of images and press a button when they heard an auditory tone of a prespecified pitch. Images could be presented with a target tone, with a distractor tone, or without a tone. Auditory target detection increased activity throughout the ventral visual cortex but lowered it in the hippocampus. These effects were accompanied by a widespread enhancement in functional connectivity between the ventral visual cortex and the hippocampus. Image category classification accuracy was higher on target tone trials than on distractor and no tone trials in the fusiform gyrus and the parahippocampal gyrus. This effect was stronger in clusters whose activity was more correlated with the hippocampus on target tone than on distractor tone trials. In agreement with accounts suggesting that subcortical noradrenergic influences play a role in temporal selection, auditory target detection also caused an increase in locus coeruleus activity and phasic pupil responses. These findings outline a network of cortical and subcortical regions that are involved in the selection and processing of information presented at behaviorally relevant moments.Significance StatementAttention influences the degree to which we remember everyday experiences. This study examines the neural mechanisms involved in committing important events to memory. It links the selection of important information in time (temporal selection) to enhanced functional connectivity between brain regions involved in perception and encoding. It also suggests the involvement of a small brainstem structure, the locus coeruleus (LC), whose degeneration is increasingly associated with cognitive decline in aging. The process of encoding behaviorally relevant events into episodic memory thus involves large-scale, coordinated activation spanning cortical and subcortical regions.

scholarly journals Perceptual restoration fails to recover unconscious processing for smooth eye movements after occipital stroke

2021 ◽  
Author(s):  
Sunwoo Kwon ◽  
Krystel R. Huxlin ◽  
Jude F. Mitchell
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Visual System ◽  
Motion Perception ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Conscious Perception ◽  
Stroke Patients ◽  
The Unconscious ◽  
Unconscious Processing

AbstractVisual pathways that guide actions do not necessarily mediate conscious perception. Patients with primary visual cortex (V1) damage lose conscious perception but often retain unconscious abilities (e.g. blindsight). Here, we asked if saccade accuracy and post-saccadic following responses (PFRs) that automatically track target motion upon saccade landing are retained when conscious perception is lost. We contrasted these behaviors in the blind and intact fields of 8 chronic V1-stroke patients, and in 8 visually-intact controls. Saccade accuracy was relatively normal in all cases. Stroke patients also had normal PFR in their intact fields, but no PFR in their blind fields. Thus, V1 damage did not spare the unconscious visual processing necessary for automatic, post-saccadic smooth eye movements. Importantly, visual training that recovered motion perception in the blind field did not restore the PFR, suggesting a clear dissociation between pathways mediating perceptual restoration and automatic actions in the V1-damaged visual system.

scholarly journals Feature-coding transitions to conjunction-coding with progression through human visual cortex

2017 ◽  
Vol 118 (6) ◽  
pp. 3194-3214 ◽  
Author(s):  
Rosemary A. Cowell ◽  
Krystal R. Leger ◽  
John T. Serences
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Temporal Cortex ◽  
Complex Stimulus ◽  
Imaging Data ◽  
Neuronal Responses ◽  
Human Visual Cortex ◽  
Early Visual Cortex ◽  
Parietal Cortices ◽  
Object Level

Identifying an object and distinguishing it from similar items depends upon the ability to perceive its component parts as conjoined into a cohesive whole, but the brain mechanisms underlying this ability remain elusive. The ventral visual processing pathway in primates is organized hierarchically: Neuronal responses in early stages are sensitive to the manipulation of simple visual features, whereas neuronal responses in subsequent stages are tuned to increasingly complex stimulus attributes. It is widely assumed that feature-coding dominates in early visual cortex whereas later visual regions employ conjunction-coding in which object representations are different from the sum of their simple feature parts. However, no study in humans has demonstrated that putative object-level codes in higher visual cortex cannot be accounted for by feature-coding and that putative feature codes in regions prior to ventral temporal cortex are not equally well characterized as object-level codes. Thus the existence of a transition from feature- to conjunction-coding in human visual cortex remains unconfirmed, and if a transition does occur its location remains unknown. By employing multivariate analysis of functional imaging data, we measure both feature-coding and conjunction-coding directly, using the same set of visual stimuli, and pit them against each other to reveal the relative dominance of one vs. the other throughout cortex. Our results reveal a transition from feature-coding in early visual cortex to conjunction-coding in both inferior temporal and posterior parietal cortices. This novel method enables the use of experimentally controlled stimulus features to investigate population-level feature and conjunction codes throughout human cortex. NEW & NOTEWORTHY We use a novel analysis of neuroimaging data to assess representations throughout visual cortex, revealing a transition from feature-coding to conjunction-coding along both ventral and dorsal pathways. Occipital cortex contains more information about spatial frequency and contour than about conjunctions of those features, whereas inferotemporal and parietal cortices contain conjunction coding sites in which there is more information about the whole stimulus than its component parts.

scholarly journals The case for primate V3

2011 ◽  
Vol 279 (1729) ◽  
pp. 625-633 ◽  
Author(s):  
David C. Lyon ◽  
Jason D. Connolly
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Visual Processing ◽  
Large Body ◽  
Dorsal Stream ◽  
Primate Species ◽  
Functional Magnetic Resonance ◽  
Field Representation ◽  
Primate Visual Cortex ◽  
Organizational Feature

The visual system in primates is represented by a remarkably large expanse of the cerebral cortex. While more precise investigative studies that can be performed in non-human primates contribute towards understanding the organization of the human brain, there are several issues of visual cortex organization in monkey species that remain unresolved. In all, more than 20 areas comprise the primate visual cortex, yet there is little agreement as to the exact number, size and visual field representation of all but three. A case in point is the third visual area, V3. It is found relatively early in the visual system hierarchy, yet over the last 40 years its organization and even its very existence have been a matter of debate among prominent neuroscientists. In this review, we discuss a large body of recent work that provides straightforward evidence for the existence of V3. In light of this, we then re-examine results from several seminal reports and provide parsimonious re-interpretations in favour of V3. We conclude with analysis of human and monkey functional magnetic resonance imaging literature to make the case that a complete V3 is an organizational feature of all primate species and may play a greater role in the dorsal stream of visual processing.

scholarly journals Alertness Training Increases Visual Processing Speed in Healthy Older Adults

2021 ◽  
pp. 095679762096552
Author(s):  
Melanie D. Penning ◽  
Adriana L. Ruiz-Rizzo ◽  
Petra Redel ◽  
Hermann J. Müller ◽  
Tiina Salminen ◽  
...  
Keyword(s):  
Older Adults ◽  
Functional Connectivity ◽  
Processing Speed ◽  
Visual Processing ◽  
Training Group ◽  
Control Group ◽  
Significant Group ◽  
Healthy Older Adults ◽  
Visual Processing Speed ◽  
Individual Training

In this study, we investigated whether alertness training in healthy older adults increases visual processing speed (VPS) and whether functional connectivity in the cingulo-opercular network predicts training gain. Using the theory of visual attention, we derived quantitative estimates of VPS before and after training. In Study 1, 75 healthy older adults participated in alertness training, active-control training, or no training ( n = 25 each). A significant Group × Session interaction indicated an increase in VPS in the alertness-training group but not in the control group, despite VPS not differing significantly between groups before training. In Study 2, 29 healthy older adults underwent resting-state functional MRI and then participated in alertness training. Pretraining functional connectivity in the cingulo-opercular network correlated with the individual training-induced change in VPS. In conclusion, results indicate that alertness training improves visual processing in older adults and that functional connectivity in the cingulo-opercular network provides a neural marker for predicting individual training gain.

scholarly journals Flow stimuli reveal ecologically appropriate responses in mouse visual cortex

2018 ◽  
Vol 115 (44) ◽  
pp. 11304-11309 ◽  
Author(s):  
Luciano Dyballa ◽  
Mahmood S. Hoseini ◽  
Maria C. Dadarlat ◽  
Steven W. Zucker ◽  
Michael P. Stryker
Keyword(s):  
Visual Cortex ◽  
Spatial Frequency ◽  
Visual System ◽  
Frequency Analysis ◽  
Visual Processing ◽  
Prey Capture ◽  
Temporal Frequency ◽  
Natural World ◽  
Spatial Frequencies ◽  
Spatial Frequency Analysis

Assessments of the mouse visual system based on spatial-frequency analysis imply that its visual capacity is low, with few neurons responding to spatial frequencies greater than 0.5 cycles per degree. However, visually mediated behaviors, such as prey capture, suggest that the mouse visual system is more precise. We introduce a stimulus class—visual flow patterns—that is more like what the mouse would encounter in the natural world than are sine-wave gratings but is more tractable for analysis than are natural images. We used 128-site silicon microelectrodes to measure the simultaneous responses of single neurons in the primary visual cortex (V1) of alert mice. While holding temporal-frequency content fixed, we explored a class of drifting patterns of black or white dots that have energy only at higher spatial frequencies. These flow stimuli evoke strong visually mediated responses well beyond those predicted by spatial-frequency analysis. Flow responses predominate in higher spatial-frequency ranges (0.15–1.6 cycles per degree), many are orientation or direction selective, and flow responses of many neurons depend strongly on sign of contrast. Many cells exhibit distributed responses across our stimulus ensemble. Together, these results challenge conventional linear approaches to visual processing and expand our understanding of the mouse’s visual capacity to behaviorally relevant ranges.

scholarly journals Functional connectivity for face processing in individuals with body dysmorphic disorder and anorexia nervosa

2015 ◽  
Vol 45 (16) ◽  
pp. 3491-3503 ◽  
Author(s):  
T. D. Moody ◽  
M. A. Sasaki ◽  
C. Bohon ◽  
M. A. Strober ◽  
S. Y. Bookheimer ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Functional Connectivity ◽  
Face Processing ◽  
Visual Processing ◽  
Body Dysmorphic Disorder ◽  
Cingulate Gyrus ◽  
Imaging Data ◽  
Posterior Cingulate ◽  
Posterior Cingulate Gyrus ◽  
Face Area

Background.Body dysmorphic disorder (BDD) and anorexia nervosa (AN) are both characterized by distorted perception of appearance. Previous studies in BDD suggest abnormalities in visual processing of own and others’ faces, but no study has examined visual processing of faces in AN, nor directly compared the two disorders in this respect.Method.We collected functional magnetic resonance imaging data on 60 individuals of equivalent age and gender in each of three groups – 20 BDD, 20 weight-restored AN, and 20 healthy controls (HC) – while they viewed images of others’ faces that contained only high or low spatial frequency information (HSF or LSF). We tested hypotheses about functional connectivity within specialized sub-networks for HSF and LSF visual processing, using psychophysiological interaction analyses.Results.The BDD group demonstrated increased functional connectivity compared to HC between left anterior occipital face area and right fusiform face area (FFA) for LSF faces, which was associated with symptom severity. Both BDD and AN groups had increased connectivity compared to HC between FFA and precuneous/posterior cingulate gyrus for LSF faces, and decreased connectivity between FFA and insula. In addition, we found that LSF connectivity between FFA and posterior cingulate gyrus was significantly associated with thoughts about own appearance in AN.Conclusions.Results suggest similar abnormal functional connectivity within higher-order systems for face processing in BDD and AN, but distinct abnormal connectivity patterns within occipito-temporal visual networks. Findings may have implications for understanding relationships between these disorders, and the pathophysiology underlying perceptual distortions.

Sign in / Sign up

Export Citation Format

Share Document