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1.
eNeuro ; 11(3)2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38479809

RESUMO

First-order thalamic nuclei receive feedforward signals from peripheral receptors and relay these signals to primary sensory cortex. Primary sensory cortex, in turn, provides reciprocal feedback to first-order thalamus. Because the vast majority of sensory thalamocortical inputs target primary sensory cortex, their complementary corticothalamic neurons are assumed to be similarly restricted to primary sensory cortex. We upend this assumption by characterizing morphologically diverse neurons in multiple mid-level visual cortical areas of the primate (Macaca mulatta) brain that provide direct feedback to the primary visual thalamus, the dorsal lateral geniculate nucleus (LGN). Although the majority of geniculocortical neurons project to primary visual cortex (V1), a minority, located mainly in the koniocellular LGN layers, provide direct input to extrastriate visual cortex. These "V1-bypassing" projections may be implicated in blindsight. We hypothesized that geniculocortical inputs directly targeting extrastriate cortex should be complemented by reciprocal corticogeniculate circuits. Using virus-mediated circuit tracing, we discovered corticogeniculate neurons throughout three mid-level extrastriate areas: MT, MST, and V4. Quantitative morphological analyses revealed nonuniform distributions of unique cell types across areas. Many extrastriate corticogeniculate neurons had spiny stellate morphology, suggesting possible targeting of koniocellular LGN layers. Importantly though, multiple morphological types were observed across areas. Such morphological diversity could suggest parallel streams of V1-bypassing corticogeniculate feedback at multiple stages of the visual processing hierarchy. Furthermore, the presence of corticogeniculate neurons across visual cortex necessitates a reevaluation of the LGN as a hub for visual information rather than a simple relay.


Assuntos
Córtex Visual , Vias Visuais , Animais , Retroalimentação , Vias Visuais/fisiologia , Tálamo/fisiologia , Macaca mulatta , Córtex Visual/fisiologia
2.
Proc Natl Acad Sci U S A ; 121(12): e2317218121, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38483997

RESUMO

Across the animal kingdom, visual predation relies on motion-sensing neurons in the superior colliculus (SC) and its orthologs. These neurons exhibit complex stimulus preferences, including direction selectivity, which is thought to be critical for tracking the unpredictable escape routes of prey. The source of direction selectivity in the SC is contested, and its contributions to predation have not been tested experimentally. Here, we use type-specific cell removal to show that narrow-field (NF) neurons in the mouse SC guide predation. In vivo recordings demonstrate that direction-selective responses of NF cells are independent of recently reported stimulus-edge effects. Monosynaptic retrograde tracing reveals that NF cells receive synaptic input from direction-selective ganglion cells. When we eliminate direction selectivity in the retina of adult mice, direction-selective responses in the SC, including in NF cells, are lost. However, eliminating retinal direction selectivity does not affect the hunting success or strategies of mice, even when direction selectivity is removed after mice have learned to hunt, and despite abolishing the gaze-stabilizing optokinetic reflex. Thus, our results identify the retinal source of direction selectivity in the SC. They show that NF cells in the SC guide predation, an essential spatial orienting task, independent of their direction selectivity, revealing behavioral multiplexing of complex neural feature preferences and highlighting the importance of feature-selective manipulations for neuroethology.


Assuntos
Neurônios , Comportamento Predatório , Camundongos , Animais , Neurônios/fisiologia , Colículos Superiores/fisiologia , Retina , Vias Visuais/fisiologia
3.
Nat Commun ; 15(1): 2466, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38503746

RESUMO

How the activity of neurons gives rise to natural vision remains a matter of intense investigation. The mid-level visual areas along the ventral stream are selective to a common class of natural images-textures-but a circuit-level understanding of this selectivity and its link to perception remains unclear. We addressed these questions in mice, first showing that they can perceptually discriminate between textures and statistically simpler spectrally matched stimuli, and between texture types. Then, at the neural level, we found that the secondary visual area (LM) exhibited a higher degree of selectivity for textures compared to the primary visual area (V1). Furthermore, textures were represented in distinct neural activity subspaces whose relative distances were found to correlate with the statistical similarity of the images and the mice's ability to discriminate between them. Notably, these dependencies were more pronounced in LM, where the texture-related subspaces were smaller than in V1, resulting in superior stimulus decoding capabilities. Together, our results demonstrate texture vision in mice, finding a linking framework between stimulus statistics, neural representations, and perceptual sensitivity-a distinct hallmark of efficient coding computations.


Assuntos
Córtex Visual , Vias Visuais , Animais , Camundongos , Estimulação Luminosa/métodos , Vias Visuais/fisiologia , Córtex Visual/fisiologia , Neurônios/fisiologia , Percepção Visual/fisiologia
4.
Neurology ; 102(7): e209156, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38447105

RESUMO

BACKGROUND AND OBJECTIVES: We aimed to assess the presence of retinal neurodegeneration independent of optic neuritis (ON) in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and to investigate the development of trans-synaptic anterograde degeneration in these patients after ON. METHODS: Cross-sectional, retrospective study of 34 adult patients with MOGAD and 23 healthy controls (HC). Clinical, optical coherence tomography (OCT), and MRI data were collected. Peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell inner plexiform layer (GCIPL) were obtained using Heidelberg Spectralis. FreeSurfer7 was used to obtain the lateral geniculate nucleus (LGN), occipital volume fractions (to total estimated intracranial volume), and occipital cortical thickness. For the anterior visual pathway, the analysis was conducted using eyes, classified based on the history of ON (Eye-ON and Eye-NON) and compared with Eye-HC. The analysis of OCT and brain volumetric measures was conducted comparing MOGAD-ON, MOGAD-NON, and HC groups. The analysis of covariance with a Bonferroni-adjusted post hoc test was used to test differences between groups and linear regression analysis to evaluate OCT/MRI associations; age and sex were considered as covariates. RESULTS: 24 (70.5%) patients had a prior ON. Median pRNFL and GCIPL thickness (um) was significantly reduced in Eye-ON vs EyeNON and HC (pRNFL: 69.4 (17.3), 89.6 (13.7), 98.2 (11.7), p < 0.001; GCIPL: 55.8 (8.7), 67.39 (8.7), 72.6 (4.5), p < 0.001). pRNFL and GCIPL thickness had a negative correlation with the number of ON episodes (p = 0.025 and p = 0.031, respectively). LGN volume fraction was significantly lower in patients with MOGAD-ON than in HC (0.33 (0.05) vs 0.39 (0.04), p = 0.002). The occipital cortical thickness was lower in MOGAD-ON compared with MOGAD-NON and HC (p = 0.010). In patients with MOGAD-ON, pRNFL correlated with LGN volume (p = 0.006), occipital thickness (p = 0.002), and the medial occipital cortex (p = 0.002), but not the lateral occipital lobe. DISCUSSION: Compared with HC, MOGAD-ON exhibits reduced retinal thickness, primarily influenced by the presence and the number of prior ON episodes. Moreover, MOGAD-ON demonstrates significant atrophy in the retinal, subcortical, and cortical regions of the visual pathway, distinguishing them from MOGAD-NON and HC. These findings suggest that in patients with MOGAD neurodegeneration is tightly correlated with damage to the involved pathway.


Assuntos
Neurite Óptica , Vias Visuais , Adulto , Humanos , Glicoproteína Mielina-Oligodendrócito , Vias Visuais/diagnóstico por imagem , Estudos Transversais , Degeneração Retrógrada , Estudos Retrospectivos , Neurite Óptica/diagnóstico por imagem , Retina
5.
Elife ; 132024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38489224

RESUMO

How neural representations preserve information about multiple stimuli is mysterious. Because tuning of individual neurons is coarse (e.g., visual receptive field diameters can exceed perceptual resolution), the populations of neurons potentially responsive to each individual stimulus can overlap, raising the question of how information about each item might be segregated and preserved in the population. We recently reported evidence for a potential solution to this problem: when two stimuli were present, some neurons in the macaque visual cortical areas V1 and V4 exhibited fluctuating firing patterns, as if they responded to only one individual stimulus at a time (Jun et al., 2022). However, whether such an information encoding strategy is ubiquitous in the visual pathway and thus could constitute a general phenomenon remains unknown. Here, we provide new evidence that such fluctuating activity is also evoked by multiple stimuli in visual areas responsible for processing visual motion (middle temporal visual area, MT), and faces (middle fundus and anterolateral face patches in inferotemporal cortex - areas MF and AL), thus extending the scope of circumstances in which fluctuating activity is observed. Furthermore, consistent with our previous results in the early visual area V1, MT exhibits fluctuations between the representations of two stimuli when these form distinguishable objects but not when they fuse into one perceived object, suggesting that fluctuating activity patterns may underlie visual object formation. Taken together, these findings point toward an updated model of how the brain preserves sensory information about multiple stimuli for subsequent processing and behavioral action.


Assuntos
Córtex Visual , Vias Visuais , Vias Visuais/fisiologia , Córtex Visual/fisiologia , Campos Visuais , Neurônios/fisiologia , Estimulação Luminosa
6.
Invest Ophthalmol Vis Sci ; 65(2): 4, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38306108

RESUMO

Purpose: A lesion to primary visual cortex (V1) in primates can produce retrograde transneuronal degeneration in the dorsal lateral geniculate nucleus (LGN) and retina. We investigated the effect of age at time of lesion on LGN volume and retinal ganglion cell (RGC) density in marmoset monkeys. Methods: Retinas and LGNs were obtained about 2 years after a unilateral left-sided V1 lesion as infants (n = 7) or young adult (n = 1). Antibodies against RBPMS were used to label all RGCs, and antibodies against CaMKII or GABAA receptors were used to label nonmidget RGCs. Cell densities were compared in the left and right hemiretina of each eye. The LGNs were stained with the nuclear marker NeuN or for Nissl substance. Results: In three animals lesioned within the first 2 postnatal weeks, the proportion of RGCs lost within 5 mm of the fovea was ∼twofold higher than after lesions at 4 or 6 weeks. There was negligible loss in the animal lesioned at 2 years of age. A positive correlation between RGC loss and LGN volume reduction was evident. No loss of CaMKII-positive or GABAA receptor-positive RGCs was apparent within 2 mm of the fovea in any of the retinas investigated. Conclusions: Susceptibility of marmoset RGCs to transneuronal degeneration is high at birth and declines over the first 6 postnatal weeks. High survival rates of CaMKII and GABAA receptor-positive RGCs implies that widefield and parasol cells are less affected by neonatal cortical lesions than are midget-pathway cells.


Assuntos
Callithrix , Células Ganglionares da Retina , Humanos , Animais , Recém-Nascido , Células Ganglionares da Retina/patologia , Receptores de GABA-A , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina , Córtex Visual Primário , Vias Visuais/patologia , Retina , Proteínas de Transporte
7.
Nat Commun ; 15(1): 849, 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38346973

RESUMO

The visual continuity illusion involves a shift in visual perception from static to dynamic vision modes when the stimuli arrive at high temporal frequency, and is critical for recognizing objects moving in the environment. However, how this illusion is encoded across the visual pathway remains poorly understood, with disparate frequency thresholds at retinal, cortical, and behavioural levels suggesting the involvement of other brain areas. Here, we employ a multimodal approach encompassing behaviour, whole-brain functional MRI, and electrophysiological measurements, for investigating the encoding of the continuity illusion in rats. Behavioural experiments report a frequency threshold of 18±2 Hz. Functional MRI reveal that superior colliculus signals transition from positive to negative at the behaviourally-driven threshold, unlike thalamic and cortical areas. Electrophysiological recordings indicate that these transitions are underpinned by neural activation/suppression. Lesions in the primary visual cortex reveal this effect to be intrinsic to the superior colliculus (under a cortical gain effect). Our findings highlight the superior colliculus' crucial involvement in encoding temporal frequency shifts, especially the change from static to dynamic vision modes.


Assuntos
Ilusões , Colículos Superiores , Ratos , Animais , Colículos Superiores/fisiologia , Visão Ocular , Percepção Visual/fisiologia , Vias Visuais/fisiologia
8.
Neuroimage Clin ; 41: 103570, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38309185

RESUMO

Impaired motion perception in schizophrenia has been associated with deficits in social-cognitive processes and with reduced activation of visual sensory regions, including the middle temporal area (MT+) and posterior superior temporal sulcus (pSTS). These findings are consistent with the recent proposal of the existence of a specific 'third visual pathway' specialized for social perception in which motion is a fundamental component. The third visual pathway transmits visual information from early sensory visual processing areas to the STS, with MT+ acting as a critical intermediary. We used functional magnetic resonance imaging to investigate functioning of this pathway during processing of naturalistic videos with explicit (real) motion and static images with implied motion cues. These measures were related to face emotion recognition and motion-perception, as measured behaviorally. Participants were 28 individuals with schizophrenia (Sz) and 20 neurotypical controls. Compared to controls, individuals with Sz showed reduced activation of third visual pathway regions (MT+, pSTS) in response to both real- and implied-motion stimuli. Dysfunction of early visual cortex and pulvinar were also associated with aberrant real-motion processing. Implied-motion stimuli additionally engaged a wide network of brain areas including parietal, motor and frontal nodes of the human mirror neuron system. The findings support concepts of MT+ as a mediator between visual sensory areas and higher-order brain and argue for greater focus on MT+ contributions to social-cognitive processing, in addition to its well-documented role in visual motion processing.


Assuntos
Percepção de Movimento , Esquizofrenia , Humanos , Esquizofrenia/diagnóstico por imagem , Vias Visuais/diagnóstico por imagem , Lobo Temporal , Encéfalo/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Mapeamento Encefálico , Percepção de Movimento/fisiologia , Estimulação Luminosa/métodos
9.
Nat Commun ; 15(1): 1570, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38383614

RESUMO

Visual systems are homogeneous structures, where repeating columnar units retinotopically cover the visual field. Each of these columns contain many of the same neuron types that are distinguished by anatomic, genetic and - generally - by functional properties. However, there are exceptions to this rule. In the 800 columns of the Drosophila eye, there is an anatomically and genetically identifiable cell type with variable functional properties, Tm9. Since anatomical connectivity shapes functional neuronal properties, we identified the presynaptic inputs of several hundred Tm9s across both optic lobes using the full adult female fly brain (FAFB) electron microscopic dataset and FlyWire connectome. Our work shows that Tm9 has three major and many sparsely distributed inputs. This differs from the presynaptic connectivity of other Tm neurons, which have only one major, and more stereotypic inputs than Tm9. Genetic synapse labeling showed that the heterogeneous wiring exists across individuals. Together, our data argue that the visual system uses heterogeneous, distributed circuit properties to achieve robust visual processing.


Assuntos
Artrópodes , Neurônios , Humanos , Animais , Feminino , Neurônios/fisiologia , Drosophila/fisiologia , Sinapses/fisiologia , Percepção Visual , Encéfalo , Vias Visuais/fisiologia
10.
PLoS One ; 19(2): e0299083, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38394261

RESUMO

The analogy between the brain and deep neural networks (DNNs) has sparked interest in neuroscience. Although DNNs have limitations, they remain valuable for modeling specific brain characteristics. This study used Skye's Oblique Grating illusion to assess DNNs' relevance to brain neural networks. We collected data on human perceptual responses to a series of visual illusions. This data was then used to assess how DNN responses to these illusions paralleled or differed from human behavior. We performed two analyses:(1) We trained DNNs to perform horizontal vs. non-horizontal classification on images with bars tilted different degrees (non-illusory images) and tested them on images with horizontal bars with different illusory strengths measured by human behavior (illusory images), finding that DNNs showed human-like illusions; (2) We performed representational similarity analysis to assess whether illusory representation existed in different layers within DNNs, finding that DNNs showed illusion-like responses to illusory images. The representational similarity between real tilted images and illusory images was calculated, which showed the highest values in the early layers and decreased layer-by-layer. Our findings suggest that DNNs could serve as potential models for explaining the mechanism of visual illusions in human brain, particularly those that may originate in early visual areas like the primary visual cortex (V1). While promising, further research is necessary to understand the nuanced differences between DNNs and human visual pathways.


Assuntos
Ilusões , Humanos , Ilusões/fisiologia , Encéfalo/fisiologia , Redes Neurais de Computação , Vias Visuais/fisiologia , Percepção Visual/fisiologia
11.
J Alzheimers Dis ; 98(1): 53-67, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38363610

RESUMO

Background: The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer's disease, have been recently defined, while little is known about its neurophysiological correlates. Objective: To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients. Methods: Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic. Results: The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings. Conclusions: Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.


Assuntos
Doenças Neurodegenerativas , Vias Visuais , Humanos , Vias Visuais/diagnóstico por imagem , Potenciais Evocados Visuais , Eletrorretinografia , Atrofia
12.
Nat Rev Neurosci ; 25(4): 237-252, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38374462

RESUMO

Sub-additivity and variability are ubiquitous response motifs in the primary visual cortex (V1). Response sub-additivity enables the construction of useful interpretations of the visual environment, whereas response variability indicates the factors that limit the precision with which the brain can do this. There is increasing evidence that experimental manipulations that elicit response sub-additivity often also quench response variability. Here, we provide an overview of these phenomena and suggest that they may have common origins. We discuss empirical findings and recent model-based insights into the functional operations, computational objectives and circuit mechanisms underlying V1 activity. These different modelling approaches all predict that response sub-additivity and variability quenching often co-occur. The phenomenology of these two response motifs, as well as many of the insights obtained about them in V1, generalize to other cortical areas. Thus, the connection between response sub-additivity and variability quenching may be a canonical motif across the cortex.


Assuntos
Córtex Visual , Humanos , Córtex Visual/fisiologia , Encéfalo , Estimulação Luminosa , Vias Visuais/fisiologia
13.
Prog Neurobiol ; 234: 102584, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38309458

RESUMO

In human and nonhuman primate brains, columnar (mesoscale) organization has been demonstrated to underlie both lower and higher order aspects of visual information processing. Previous studies have focused on identifying functional preferences of mesoscale domains in specific areas; but there has been little understanding of how mesoscale domains may cooperatively respond to single visual stimuli across dorsal and ventral pathways. Here, we have developed ultrahigh-field 7 T fMRI methods to enable simultaneous mapping, in individual macaque monkeys, of response in both dorsal and ventral pathways to single simple color and motion stimuli. We provide the first evidence that anatomical V2 cytochrome oxidase-stained stripes are well aligned with fMRI maps of V2 stripes, settling a long-standing controversy. In the ventral pathway, a systematic array of paired color and luminance processing domains across V4 was revealed, suggesting a novel organization for surface information processing. In the dorsal pathway, in addition to high quality motion direction maps of MT, MST and V3A, alternating color and motion direction domains in V3 are revealed. As well, submillimeter motion domains were observed in peripheral LIPd and LIPv. In sum, our study provides a novel global snapshot of how mesoscale networks in the ventral and dorsal visual pathways form the organizational basis of visual objection recognition and vision for action.


Assuntos
Macaca , Córtex Visual , Animais , Humanos , Vias Visuais/diagnóstico por imagem , Vias Visuais/fisiologia , Imageamento por Ressonância Magnética/métodos , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Mapeamento Encefálico
14.
eNeuro ; 11(1)2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38164595

RESUMO

To generate a coherent visual percept, information from both eyes must be appropriately transmitted into the brain, where binocular integration forms the substrate for visuomotor behaviors. To establish the anatomical substrate for binocular integration, the presence of bilateral eyes and interaction of both optic nerves during retinotectal development play a key role. However, the extent to which embryonic monocularly derived visual circuits can convey visuomotor behaviors is unknown. In this study, we assessed the retinotectal anatomy and visuomotor performance of embryonically generated one-eyed tadpoles. In one-eyed animals, the axons of retinal ganglion cells from the singular remaining eye exhibited striking irregularities in their central projections in the brain, generating a noncanonical ipsilateral retinotectal projection. This data is indicative of impaired pathfinding abilities. We further show that these novel projections are correlated with an impairment of behavioral compensation for the loss of one eye.


Assuntos
Retina , Colículos Superiores , Animais , Retina/fisiologia , Xenopus laevis , Colículos Superiores/anatomia & histologia , Vias Visuais/fisiologia , Nervo Óptico
15.
Sci Rep ; 14(1): 453, 2024 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-38172589

RESUMO

Anterior Visual Pathway (aVP) damage may be linked to diverse inflammatory, degenerative and/or vascular conditions. Currently however, a standardized methodological framework for extracting MRI biomarkers of the aVP is not available. We used high-resolution, 3-D MRI data to generate a probabilistic anatomical atlas of the normal aVP and its intraorbital (iOrb), intracanalicular (iCan), intracranial (iCran), optic chiasm (OC), and tract (OT) subdivisions. We acquired 0.6 mm3 steady-state free-precession images from 24 healthy participants using a 3 T scanner. aVP masks were obtained by manual segmentation of each aVP subdivision. Mask straightening and normalization with cross-sectional area (CSA) preservation were obtained using scripts developed in-house. A probabilistic atlas ("aVP-24") was generated by averaging left and right sides of all subjects. Leave-one-out cross-validation with respect to interindividual variability was performed employing the Dice Similarity Index (DSI). Spatially normalized representations of the aVP subdivisions were generated. Overlapping CSA values before and after normalization demonstrate preservation of the aVP cross-section. Volume, length, CSA, and ellipticity index (ε) biometrics were extracted. The aVP-24 morphology followed previous descriptions from the gross anatomy. Atlas spatial validation DSI scores of 0.85 in 50% and 0.77 in 95% of participants indicated good generalizability across the subjects. The proposed MRI standardization framework allows for previously unavailable, geometrically unbiased biometric data of the entire aVP and provides the base for future spatial-resolved, group-level investigations.


Assuntos
Doenças Vasculares , Vias Visuais , Humanos , Imageamento por Ressonância Magnética/métodos , Quiasma Óptico , Biometria , Processamento de Imagem Assistida por Computador/métodos
16.
Zhonghua Yan Ke Za Zhi ; 60(1): 84-87, 2024 Jan 11.
Artigo em Chinês | MEDLINE | ID: mdl-38199773

RESUMO

A 33-year-old female presented to the ophthalmology clinic with right periorbital redness and pain for 12 hours. CT revealed right optic nerve thickening and enlargement. Cranial MRI demonstrated abnormalities in the corpus callosum, bilateral hippocampi, thalamus, basal ganglia, temporal-parietal lobes, and the left frontal lobe. Ocular B-scan ultrasound showed elevated optic disc and high echogenic signals in the right vitreous cavity. The patient had a history of surgical resection, radiation therapy, and chemotherapy for a left occipital glioma two years prior, with pathology indicating astrocytoma (World Health Organization Grade Ⅱ). Combining the patient's history and diagnostic findings, the confirmed diagnosis is bilateral occipital astrocytoma with invasion into the right transverse sinus, bilateral optic pathways involvement related to the left occipital astrocytoma, and seeding of astrocytoma in the right vitreous cavity.


Assuntos
Astrocitoma , Vias Visuais , Feminino , Humanos , Adulto , Olho , Nervo Óptico , Face
17.
Nat Commun ; 15(1): 516, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38225259

RESUMO

The coding privilege of end-spectral hues (red and blue) in the early visual cortex has been reported in primates. However, the origin of such bias remains unclear. Here, we provide a complete picture of the end-spectral bias in visual system by measuring fMRI signals and spiking activities in macaques. The correlated end-spectral biases between the LGN and V1 suggest a subcortical source for asymmetric coding. Along the ventral pathway from V1 to V4, red bias against green peaked in V1 and then declined, whereas blue bias against yellow showed an increasing trend. The feedforward and recurrent modifications of end-spectral bias were further revealed by dynamic causal modeling analysis. Moreover, we found that the strongest end-spectral bias in V1 was in layer 4C[Formula: see text]. Our results suggest that end-spectral bias already exists in the LGN and is transmitted to V1 mainly through the parvocellular pathway, then embellished by cortical processing.


Assuntos
Córtex Visual , Vias Visuais , Animais , Córtex Visual/diagnóstico por imagem , Primatas , Macaca , Imageamento por Ressonância Magnética/métodos , Corpos Geniculados , Estimulação Luminosa/métodos
18.
PLoS Biol ; 22(1): e3002375, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38236815

RESUMO

Detecting imminent collisions is essential for survival. Here, we used high-resolution fMRI at 7 Tesla to investigate the role of attention and consciousness for detecting collision trajectory in human subcortical pathways. Healthy participants can precisely discriminate collision from near-miss trajectory of an approaching object, with pupil size change reflecting collision sensitivity. Subcortical pathways from the superior colliculus (SC) to the ventromedial pulvinar (vmPul) and ventral tegmental area (VTA) exhibited collision-sensitive responses even when participants were not paying attention to the looming stimuli. For hemianopic patients with unilateral lesions of the geniculostriate pathway, the ipsilesional SC and VTA showed significant activation to collision stimuli in their scotoma. Furthermore, stronger SC responses predicted better behavioral performance in collision detection even in the absence of awareness. Therefore, human tectofugal pathways could automatically detect collision trajectories without the observers' attention to and awareness of looming stimuli, supporting "blindsight" detection of impending visual threats.


Assuntos
Percepção de Movimento , Pulvinar , Humanos , Percepção de Movimento/fisiologia , Colículos Superiores/fisiologia , Imageamento por Ressonância Magnética , Pulvinar/diagnóstico por imagem , Estimulação Luminosa , Vias Visuais/fisiologia
19.
BMJ Open Ophthalmol ; 9(1)2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38237934

RESUMO

OBJECTIVE: To explore different performances in the magnocellular (MC) and parvocellular (PC) visual pathways in patients with primary open-angle glaucoma (POAG) and to objectively assess impairment in early stage of POAG. METHODS AND ANALYSIS: This is a cross-sectional study. MC and PC visual pathways were assessed using isolated-check visual evoked potential (ic-VEP). Visual acuity, intraocular pressure, fundus examination, optical coherence tomography and visual field were measured. Signal-to-noise ratios (SNRs), mediated by ic-VEP were recorded. The Spearman's correlation analysis was used to estimate the relationships between visual functions and structures. Receiver-operating-characteristic (ROC) curves were used to estimate the accuracy in detection of early POAG. RESULTS: 60 participants (30 early POAG eyes and 30 age-matched control subjects) were recruited. MC visual pathway showed a non-linear response function, while PC visual pathway was a linear response function as contrast increased. Early POAG eyes exhibited significantly weaker initial contrast gains and lower maximum responses in the MC visual pathway (p=0.001, p=0.004, respectively). The SNRs at 8% and 32% depths of modulation (DOM) were significantly correlated with temporal-side retinal nerve fibre layer (RNFL) thickness in early POAG in MC-biased stimulation (p=0.017, p=0.020, respectively). The areas under ROC of 16% DOM were 0.780 (sensitivity 80.0%, specificity 63.3%) with the cut-off SNR of 2.07. CONCLUSIONS: The MC visual pathway was damaged in the early stage of POAG. The SNRs at 8% and 32% DOM of MC-biased stimulation were significantly correlated with temporal-side RNFL thickness in early POAG, which helped in understanding the mechanisms of visual impairment in the early stage of POAG.


Assuntos
Glaucoma de Ângulo Aberto , Humanos , Glaucoma de Ângulo Aberto/diagnóstico , Potenciais Evocados Visuais , Vias Visuais , Estudos Transversais , Células Ganglionares da Retina
20.
Cereb Cortex ; 34(2)2024 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-38183210

RESUMO

The neuronal composition of homologous brain regions in different primates is important for understanding their processing capacities. Primary visual cortex (V1) has been widely studied in different members of the catarrhines. Neuronal density is considered to be central in defining the structure-function relationship. In human, there are large variations in the reported neuronal density from prior studies. We found the neuronal density in human V1 was 79,000 neurons/mm3, which is 35% of the neuronal density previously determined in macaque V1. Laminar density was proportionally similar between human and macaque. In V1, the ocular dominance column (ODC) contains the circuits for the emergence of orientation preference and spatial processing of a point image in many mammalian species. Analysis of the total neurons in an ODC and of the full number of neurons in macular vision (the central 15°) indicates that humans have 1.3× more neurons than macaques even though the density of neurons in macaque is 3× the density in human V1. We propose that the number of neurons in a functional processing unit rather than the number of neurons under a mm2 of cortex is more appropriate for cortical comparisons across species.


Assuntos
Macaca , Córtex Visual , Animais , Humanos , Córtex Visual/fisiologia , Neurônios/fisiologia , Visão Ocular , Vias Visuais/fisiologia , Mamíferos
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