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Neuroscience Bulletin Oct 2021Visual object recognition in humans and nonhuman primates is achieved by the ventral visual pathway (ventral occipital-temporal cortex, VOTC), which shows a...
Visual object recognition in humans and nonhuman primates is achieved by the ventral visual pathway (ventral occipital-temporal cortex, VOTC), which shows a well-documented object domain structure. An on-going question is what type of information is processed in the higher-order VOTC that underlies such observations, with recent evidence suggesting effects of certain visual features. Combining computational vision models, fMRI experiment using a parametric-modulation approach, and natural image statistics of common objects, we depicted the neural distribution of a comprehensive set of visual features in the VOTC, identifying voxel sensitivities with specific feature sets across geometry/shape, Fourier power, and color. The visual feature combination pattern in the VOTC is significantly explained by their relationships to different types of response-action computation (fight-or-flight, navigation, and manipulation), as derived from behavioral ratings and natural image statistics. These results offer a comprehensive visual feature map in the VOTC and a plausible theoretical explanation as a mapping onto different types of downstream response-action systems.
Topics: Animals; Brain Mapping; Humans; Magnetic Resonance Imaging; Occipital Lobe; Pattern Recognition, Visual; Photic Stimulation; Temporal Lobe; Visual Pathways; Visual Perception
PubMed: 34215969
DOI: 10.1007/s12264-021-00734-4 -
Multiple Sclerosis (Houndmills,... Nov 2014Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant.... (Review)
Review
Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant. The visual pathway represents a model of acute focal central nervous system (CNS) damage, through acute optic neuritis and retinal periphlebitis, as well as a model of chronic, diffuse CNS damage through chronic retinopathy and optic neuropathy. The optic pathway can be accurately evaluated in detail, due to the availability of highly sensitive imaging techniques (e.g. magnetic resonance imaging or optical coherent tomography) or electrophysiological tests (multifocal visual evoked potentials or electroretinography). These techniques allow the interactions between the different processes at play to be evaluated, such as inflammation, demyelination, axonal damage and neurodegeneration. Moreover, these features mean that the visual pathway can be used as a model to test new neuroprotective or regenerative therapies.
Topics: Animals; Brain; Evoked Potentials, Visual; Humans; Multiple Sclerosis; Visual Pathways
PubMed: 25013155
DOI: 10.1177/1352458514542862 -
Neuroscience Aug 2021Some patients with damage to the primary visual cortex (V1) exhibit visuomotor ability, despite loss of visual awareness, a phenomenon termed "blindsight". We review a... (Review)
Review
Some patients with damage to the primary visual cortex (V1) exhibit visuomotor ability, despite loss of visual awareness, a phenomenon termed "blindsight". We review a series of studies conducted mainly in our laboratory on macaque monkeys with unilateral V1 lesioning to reveal the neural pathways underlying visuomotor transformation and the cognitive capabilities retained in blindsight. After lesioning, it takes several weeks for the recovery of visually guided saccades toward the lesion-affected visual field. In addition to the lateral geniculate nucleus, the pathway from the superior colliculus to the pulvinar participates in visuomotor processing in blindsight. At the cortical level, bilateral lateral intraparietal regions become critically involved in the saccade control. These results suggest that the visual circuits experience drastic changes while the monkey acquires blindsight. In these animals, analysis based on signal detection theory adapted to behavior in the "Yes-No" task indicates reduced sensitivity to visual targets, suggesting that visual awareness is impaired. Saccades become less accurate, decisions become less deliberate, and some forms of bottom-up attention are impaired. However, a variety of cognitive functions are retained such as saliency detection during free viewing, top-down attention, short-term spatial memory, and associative learning. These observations indicate that blindsight is not a low-level sensory-motor response, but the residual visual inputs can access these cognitive capabilities. Based on these results we suggest that the macaque model of blindsight replicates type II blindsight patients who experience some "feeling" of objects, which guides cognitive capabilities that we naïvely think are not possible without phenomenal consciousness.
Topics: Animals; Geniculate Bodies; Humans; Macaca; Photic Stimulation; Saccades; Visual Cortex; Visual Pathways; Visual Perception
PubMed: 34153356
DOI: 10.1016/j.neuroscience.2021.06.022 -
Trends in Cognitive Sciences Dec 2022A rich behavioral literature has shown that human object recognition is supported by a representation of shape that is tolerant to variations in an object's appearance.... (Review)
Review
A rich behavioral literature has shown that human object recognition is supported by a representation of shape that is tolerant to variations in an object's appearance. Such 'global' shape representations are achieved by describing objects via the spatial arrangement of their local features, or structure, rather than by the appearance of the features themselves. However, accumulating evidence suggests that the ventral visual pathway - the primary substrate underlying object recognition - may not represent global shape. Instead, ventral representations may be better described as a basis set of local image features. We suggest that this evidence forces a reevaluation of the role of the ventral pathway in object perception and posits a broader network for shape perception that encompasses contributions from the dorsal pathway.
Topics: Humans; Visual Pathways; Pattern Recognition, Visual; Visual Perception; Brain; Magnetic Resonance Imaging
PubMed: 36272937
DOI: 10.1016/j.tics.2022.09.019 -
Molecular Neurobiology Jul 2021Visual disabilities in central nervous system autoimmune diseases such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE),... (Review)
Review
Visual disabilities in central nervous system autoimmune diseases such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are important symptoms. Past studies have focused on neuro-inflammatory changes and demyelination in the white matter of the brain and spinal cord. In MS, neuro-inflammatory lesions have been diagnosed in the visual pathway; the lesions may perturb visual function. Similarly, neuropathological changes in the retina and optic nerves have been found in animals with chronic EAE. Although the retina and optic nerves are immunologically privileged sites via the blood-retina barrier and blood-brain barrier, respectively, inflammation can occur via other routes, such as the uvea (e.g., iris and choroid) and cerebrospinal fluid in the meninges. This review primarily addresses the direct involvement of the blood-retina barrier and the blood-brain barrier in the development of retinitis and optic neuritis in EAE models. Additional routes, including pro-inflammatory mediator-filled choroidal and subarachnoid spaces, are also discussed with respect to their roles in EAE-induced visual disability and as analogues of MS in humans.
Topics: Animals; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Humans; Multiple Sclerosis; Optic Neuritis; Uveitis; Vision Disorders; Visual Pathways
PubMed: 33745114
DOI: 10.1007/s12035-021-02355-4 -
Trends in Cognitive Sciences Jul 2021
Topics: Cognition; Humans; Motion Perception; Visual Cortex; Visual Pathways
PubMed: 34024730
DOI: 10.1016/j.tics.2021.04.002 -
Protein & Cell Nov 201870%-80% of our sensory input comes from vision. Light hit the retina at the back of our eyes and the visual information is relayed into the dorsal lateral geniculate... (Review)
Review
70%-80% of our sensory input comes from vision. Light hit the retina at the back of our eyes and the visual information is relayed into the dorsal lateral geniculate nuclei (dLGN) and primary visual cortex (V1) thereafter, constituting the image-forming visual circuit. Molecular cues are one of the key factors to guide the wiring and refinement of the image-forming visual circuit during pre- and post-embryonic stages. Distinct molecular cues are involved in different developmental stages and nucleus, suggesting diverse guidance mechanisms. In this review, we summarize molecular guidance cues throughout the image-forming visual circuit, including chiasm determination, eye-specific segregation and refinement in the dLGN, and at last the reciprocal connections between the dLGN and V1.
Topics: Animals; Geniculate Bodies; Humans; Visual Cortex; Visual Pathways
PubMed: 29181831
DOI: 10.1007/s13238-017-0490-7 -
Brain and Nerve = Shinkei Kenkyu No... Nov 2016The parietal association cortex comprises the superior and inferior parietal lobules, the precuneus and the cortices in the intraparietal, parietooccipital and lunate... (Review)
Review
The parietal association cortex comprises the superior and inferior parietal lobules, the precuneus and the cortices in the intraparietal, parietooccipital and lunate sulci. By processing somatic, visual, acoustic and vestibular sensory information, the parietal association cortex plays a pivotal role in spatial cognition and motor control of the eyes and the extremities. Sensory information from the primary and secondary somatosensory areas enters the superior parietal lobule and is transferred to the inferior parietal lobule. Visual information is processed through the dorsal visual pathway and it reaches the inferior parietal lobule, the intraparietal sulcus and the precuneus. Acoustic information is transferred posteriorly from the primary acoustic area, and it reaches the posterior region of the inferior parietal lobule. The areas in the intraparietal sulcus project to the premotor area, the frontal eye fields, and the prefrontal area. These areas are involved in the control of ocular movements, reaching and grasping of the upper extremities, and spatial working memory. The posterior region of the inferior parietal lobule and the precuneus both project either directly, or indirectly via the posterior cingulate gyrus, to the parahippocampal and entorhinal cortices. Both these areas are strongly associated with hippocampal functions for long-term memory formation.
Topics: Animals; Eye Movements; Hippocampus; Humans; Motor Cortex; Neural Pathways; Parietal Lobe; Visual Pathways
PubMed: 27852021
DOI: 10.11477/mf.1416200594 -
AJNR. American Journal of Neuroradiology May 2022DTI studies of patients with primary open-angle glaucoma have demonstrated that glaucomatous degeneration is not confined to the retina but involves the entire visual...
BACKGROUND AND PURPOSE
DTI studies of patients with primary open-angle glaucoma have demonstrated that glaucomatous degeneration is not confined to the retina but involves the entire visual pathway. Due to the lack of direct biologic interpretation of DTI parameters, the structural nature of this degeneration is still poorly understood. We used neurite orientation dispersion and density imaging (NODDI) to characterize the microstructural changes in the pregeniculate optic tracts and the postgeniculate optic radiations of patients with primary open-angle glaucoma, to better understand the mechanisms underlying these changes.
MATERIALS AND METHODS
T1- and multishell diffusion-weighted scans were obtained from 23 patients with primary open-angle glaucoma and 29 controls. NODDI parametric maps were produced from the diffusion-weighted scans, and probabilistic tractography was used to track the optic tracts and optic radiations. NODDI parameters were computed for the tracked pathways, and the measures were compared between both groups. The retinal nerve fiber layer thickness and visual field loss were assessed for the patients with glaucoma.
RESULTS
The optic tracts of the patients with glaucoma showed a higher orientation dispersion index and a lower neurite density index compared with the controls (< .001 and = .001, respectively), while their optic radiations showed a higher orientation dispersion index only (= .003).
CONCLUSIONS
The pregeniculate visual pathways of the patients with primary open-angle glaucoma exhibited a loss of both axonal coherence and density, while the postgeniculate pathways exhibited a loss of axonal coherence only. Further longitudinal studies are needed to assess the progression of NODDI alterations in the visual pathways of patients with primary open-angle glaucoma across time.
Topics: Diffusion Magnetic Resonance Imaging; Diffusion Tensor Imaging; Glaucoma, Open-Angle; Humans; Leukoaraiosis; Neurites; Visual Pathways; White Matter
PubMed: 35450857
DOI: 10.3174/ajnr.A7495 -
Philosophical Transactions of the Royal... Jun 2016One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The... (Review)
Review
One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se, and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope.This article is part of the themed issue 'Vision in our three-dimensional world'.
Topics: Animals; Depth Perception; Macaca; Vision Disparity; Visual Pathways
PubMed: 27269602
DOI: 10.1098/rstb.2015.0259