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PLoS Biology Aug 2023Understanding the dynamics of stability/plasticity balances during adulthood is pivotal for learning, disease, and recovery from injury. However, the brain-wide...
Understanding the dynamics of stability/plasticity balances during adulthood is pivotal for learning, disease, and recovery from injury. However, the brain-wide topography of sensory remapping remains unknown. Here, using a first-of-its-kind setup for delivering patterned visual stimuli in a rodent magnetic resonance imaging (MRI) scanner, coupled with biologically inspired computational models, we noninvasively mapped brain-wide properties-receptive fields (RFs) and spatial frequency (SF) tuning curves-that were insofar only available from invasive electrophysiology or optical imaging. We then tracked the RF dynamics in the chronic visual deprivation model (VDM) of plasticity and found that light exposure progressively promoted a large-scale topographic remapping in adult rats. Upon light exposure, the initially unspecialized visual pathway progressively evidenced sharpened RFs (smaller and more spatially selective) and enhanced SF tuning curves. Our findings reveal that visual experience following VDM reshapes both structure and function of the visual system and shifts the stability/plasticity balance in adults.
Topics: Rats; Animals; Visual Pathways; Brain; Learning; Optical Imaging
PubMed: 37590177
DOI: 10.1371/journal.pbio.3002229 -
Journal of Cognitive Neuroscience Oct 2023Deep convolutional neural networks (DCNNs) have become the state-of-the-art computational models of biological object recognition. Their remarkable success has helped... (Review)
Review
Deep convolutional neural networks (DCNNs) have become the state-of-the-art computational models of biological object recognition. Their remarkable success has helped vision science break new ground, and recent efforts have started to transfer this achievement to research on biological face recognition. In this regard, face detection can be investigated by comparing face-selective biological neurons and brain areas to artificial neurons and model layers. Similarly, face identification can be examined by comparing in vivo and in silico multidimensional "face spaces." In this review, we summarize the first studies that use DCNNs to model biological face recognition. On the basis of a broad spectrum of behavioral and computational evidence, we conclude that DCNNs are useful models that closely resemble the general hierarchical organization of face recognition in the ventral visual pathway and the core face network. In two exemplary spotlights, we emphasize the unique scientific contributions of these models. First, studies on face detection in DCNNs indicate that elementary face selectivity emerges automatically through feedforward processing even in the absence of visual experience. Second, studies on face identification in DCNNs suggest that identity-specific experience and generative mechanisms facilitate this particular challenge. Taken together, as this novel modeling approach enables close control of predisposition (i.e., architecture) and experience (i.e., training data), it may be suited to inform long-standing debates on the substrates of biological face recognition.
Topics: Humans; Facial Recognition; Neural Networks, Computer; Visual Perception; Brain; Neurons
PubMed: 37584587
DOI: 10.1162/jocn_a_02040 -
Current Biology : CB Jul 2023Cephalopods are highly visual animals with camera-type eyes, large brains, and a rich repertoire of visually guided behaviors. However, the cephalopod brain evolved...
Cephalopods are highly visual animals with camera-type eyes, large brains, and a rich repertoire of visually guided behaviors. However, the cephalopod brain evolved independently from those of other highly visual species, such as vertebrates; therefore, the neural circuits that process sensory information are profoundly different. It is largely unknown how their powerful but unique visual system functions, as there have been no direct neural measurements of visual responses in the cephalopod brain. In this study, we used two-photon calcium imaging to record visually evoked responses in the primary visual processing center of the octopus central brain, the optic lobe, to determine how basic features of the visual scene are represented and organized. We found spatially localized receptive fields for light (ON) and dark (OFF) stimuli, which were retinotopically organized across the optic lobe, demonstrating a hallmark of visual system organization shared across many species. An examination of these responses revealed transformations of the visual representation across the layers of the optic lobe, including the emergence of the OFF pathway and increased size selectivity. We also identified asymmetries in the spatial processing of ON and OFF stimuli, which suggest unique circuit mechanisms for form processing that may have evolved to suit the specific demands of processing an underwater visual scene. This study provides insight into the neural processing and functional organization of the octopus visual system, highlighting both shared and unique aspects, and lays a foundation for future studies of the neural circuits that mediate visual processing and behavior in cephalopods.
Topics: Animals; Octopodiformes; Eye; Visual Perception; Nervous System; Visual Pathways
PubMed: 37343556
DOI: 10.1016/j.cub.2023.05.069 -
IEEE Transactions on Pattern Analysis... Aug 2023Data augmentation is practically helpful for visual recognition, especially at the time of data scarcity. However, such success is only limited to quite a few light...
Data augmentation is practically helpful for visual recognition, especially at the time of data scarcity. However, such success is only limited to quite a few light augmentations (e.g., random crop, flip). Heavy augmentations are either unstable or show adverse effects during training, owing to the big gap between the original and augmented images. This paper introduces a novel network design, noted as Augmentation Pathways (AP), to systematically stabilize training on a much wider range of augmentation policies. Notably, AP tames various heavy data augmentations and stably boosts performance without a careful selection among augmentation policies. Unlike traditional single pathway, augmented images are processed in different neural paths. The main pathway handles the light augmentations, while other pathways focus on the heavier augmentations. By interacting with multiple paths in a dependent manner, the backbone network robustly learns from shared visual patterns among augmentations, and suppresses the side effect of heavy augmentations at the same time. Furthermore, we extend AP to high-order versions for high-order scenarios, demonstrating its robustness and flexibility in practical usage. Experimental results on ImageNet demonstrate the compatibility and effectiveness on a much wider range of augmentations, while consuming fewer parameters and lower computational costs at inference time.
PubMed: 37027762
DOI: 10.1109/TPAMI.2023.3250330 -
Eye and Brain 2023A putative mechanism of neurodegeneration in multiple sclerosis (MS) is trans-synaptic degeneration (TSD), whereby injury to a neuron leads to degeneration of... (Review)
Review
A putative mechanism of neurodegeneration in multiple sclerosis (MS) is trans-synaptic degeneration (TSD), whereby injury to a neuron leads to degeneration of synaptically connected neurons. The visual system is commonly involved in MS and provides an ideal model to study TSD given its well-defined structure. TSD may occur in an anterograde direction (optic neuropathy causing degeneration in the posterior visual pathway including the optic radiations and occipital gray matter) and/or retrograde direction (posterior visual pathway lesions causing retinal degeneration). In the current review, we discuss evidence supporting the presence of anterograde and retrograde TSD in the visual system in MS.
PubMed: 38169913
DOI: 10.2147/EB.S389632 -
Cureus Aug 2023Intracranial tumors are treated through a minimally invasive procedure called stereotactic radiosurgery (SRS), which uses precisely targeted radiation beams. When SRS is... (Review)
Review
Intracranial tumors are treated through a minimally invasive procedure called stereotactic radiosurgery (SRS), which uses precisely targeted radiation beams. When SRS is used to treat tumors in or near the optic pathway, which is responsible for transmitting visual information from the eyes to the brain, it is essential to assess the effects of treatment on visual function. The optic pathway is considered relatively radiation-sensitive, and high doses of radiation can lead to visual impairment or loss. Various methods can be used to assess the effects of SRS on the optic pathway, including visual acuity testing, visual field testing, and imaging studies. These assessments can be performed before and after treatment to track changes in visual function and detect potential complications or side effects. Assessing the optic pathway after management with SRS for intracranial tumors is essential to the treatment process to ensure that patients receive the best possible outcomes while minimizing the risk of complications. Close collaboration between the multidisciplinary team is often necessary to optimize treatment planning and monitoring of treatment response. In this review, we conducted an extensive analysis of the effects of radiation in patients with intracranial tumors after receiving radiotherapy.
PubMed: 37719564
DOI: 10.7759/cureus.43538 -
Fa Yi Xue Za Zhi Aug 2023To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.
OBJECTIVES
To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.
METHODS
Typical cases of visual field defects caused by injuries to the optic chiasm, optic tracts, optic radiations, and visual cortex were selected. Visual field examinations, visual evoked potential (VEP) and multifocal visual evolved potential (mfVEP) measurements, craniocerebral CT/MRI, and retinal optical coherence tomography (OCT) were performed, respectively, and the aforementioned visual electrophysiological and neuroimaging indicators were analyzed comprehensively.
RESULTS
The electrophysiological manifestations of visual field defects caused by optic chiasm injuries were bitemporal hemianopsia mfVEP abnormalities. The visual field defects caused by optic tract, optic radiation, and visual cortex injuries were all manifested homonymous hemianopsia mfVEP abnormalities contralateral to the lesion. Mild relative afferent pupil disorder (RAPD) and characteristic optic nerve atrophy were observed in hemianopsia patients with optic tract injuries, but not in patients with optic radiation or visual cortex injuries. Neuroimaging could provide morphological evidence of damages to the optic chiasm and its posterior visual pathway.
CONCLUSIONS
Visual field defects caused by optic chiasm, optic tract, optic radiation, and visual cortex injuries have their respective characteristics. The combined application of mfVEP and static visual field measurements, in combination with neuroimaging, can maximize the assessment of the location and degree of visual pathway damage, providing an effective scheme for the identification of such injuries.
Topics: Humans; Optic Chiasm; Visual Pathways; Visual Fields; Evoked Potentials, Visual; Random Amplified Polymorphic DNA Technique; Hemianopsia; Vision Disorders; Optic Nerve Injuries; Brain Injuries, Traumatic
PubMed: 37859473
DOI: 10.12116/j.issn.1004-5619.2023.230309 -
International Immunopharmacology Nov 2023The abnormal polarisation of microglial cells (MGs) following retinal ischemia/reperfusion (RIR) initiates neuroinflammation and progressive death of retinal ganglion...
PURPOSE
The abnormal polarisation of microglial cells (MGs) following retinal ischemia/reperfusion (RIR) initiates neuroinflammation and progressive death of retinal ganglion cells (RGCs), causing increasingly severe and irreversible visual dysfunction. Roflumilast (Roflu) is a promising candidate for treating neuroinflammatory diseases. This study aimed to explore whether Roflu displayed a cytoprotective effect against RIR-induced neuroinflammation and to characterise the underlying signalling pathway.
METHODS
The effects and mechanism of Roflu against RIR injury were investigated in C57BL/6J mice and the BV2 cell line. We used quantitative real-time PCR and enzyme-linked immunosorbent assay to examine the levels of inflammatory factors. Furthermore, haematoxylin and eosin and immunofluorescence (IF) stainings were used to assess the morphology of the retina and the states of MGs and RGCs. Reactive oxygen species (ROS) levels were examined using a ROS assay kit, while whole-genome sequencing analysis was conducted to identify altered pathways and molecules. Western blotting and IF staining were used to quantify the proteins associated with the nuclear factor erythroid 2-related factor 2 (Nrf2)/stimulator of interferon gene (STING)/nuclear factor kappa beta (NF-κB) pathway.
RESULTS
MG polarisation includes the pro-inflammatory and neurotoxic M1 phenotype as well as the anti-inflammatory and neuroprotective M2 phenotype. Roflu significantly attenuated MG activation and contributed to a shift in the MG phenotype from M1 to M2. Moreover, Roflu decreased ROS release and increased heme oxygenase 1 and NAD(P)H quinone oxidoreductase 1 expression. In vitro and in vivo experiments validated that Roflu exerted its neuroprotective effects primarily by upregulating the Nrf2/STING/NF-κB pathway. However, these effects were abrogated when the Nrf2 expression was inhibited by pharmacological or genetic manipulation.
CONCLUSIONS
Roflu suppressed RIR-induced neuroinflammation by driving the shift of MG polarisation from M1 to M2 phenotype, which was mediated by the upregulation of the Nrf2/STING/NK-κB pathway.
Topics: Mice; Animals; NF-kappa B; Neuroinflammatory Diseases; NF-E2-Related Factor 2; Microglia; Reactive Oxygen Species; Inflammation; Mice, Inbred C57BL; Phenotype; Retina; Reperfusion Injury; Ischemia
PubMed: 37751655
DOI: 10.1016/j.intimp.2023.110952 -
Ecotoxicology and Environmental Safety Sep 2023Nearly all modern life depends on artificial light; however, it does cause health problems. With certain restrictions of artificial light emitting technology, the...
Nearly all modern life depends on artificial light; however, it does cause health problems. With certain restrictions of artificial light emitting technology, the influence of the light spectrum is inevitable. The most remarkable problem is its overload in the short wavelength component. Short wavelength artificial light has a wide range of influences from ocular development to mental problems. The visual neuronal pathway, as the primary light-sensing structure, may contain the fundamental mechanism of all light-induced abnormalities. However, how the artificial light spectrum shapes the visual neuronal pathway during development in mammals is poorly understood. We placed C57BL/6 mice in three different spectrum environments (full-spectrum white light: 400-750 nm; violet light: 400 ± 20 nm; green light: 510 ± 20 nm) beginning at eye opening, with a fixed light time of 7:00-19:00. During development, we assessed the ocular axial dimension, visual function and retinal neurons. After two weeks under short wavelength conditions, the ocular axial length (AL), anterior chamber depth (ACD) and length of lens thickness, real vitreous chamber depth and retinal thickness (LLVR) were shorter, visual acuity (VA) decreased, and retinal electrical activity was impaired. The density of S-cones in the dorsal and ventral retinas both decreased after one week under short wavelength conditions. In the ventral retina, it increased after three weeks. Retinal ganglion cell (RGC) density and axon thickness were not influenced; however, the axonal terminals in the lateral geniculate nucleus (LGN) were less clustered and sparse. Amacrine cells (ACs) were significantly more activated. Green light has few effects. The KEGG and GO enrichment analyses showed that many genes related to neural circuitry, synaptic formation and neurotransmitter function were differentially expressed in the short wavelength light group. In conclusion, exposure to short wavelength artificial light in the early stage of vision-dependent development in mice delayed the development of the visual pathway. The axon terminus structure and neurotransmitter function may be the major suffering.
Topics: Animals; Mice; Mice, Inbred C57BL; Retina; Retinal Cone Photoreceptor Cells; Retinal Ganglion Cells; Neural Pathways; Mammals
PubMed: 37494734
DOI: 10.1016/j.ecoenv.2023.115282 -
Journal of Inflammation Research 2023Phlebitis is a common complication of intravenous administration and greatly affects clinical outcomes, patient satisfaction, and health-care expenditure. Numerous... (Review)
Review
BACKGROUND
Phlebitis is a common complication of intravenous administration and greatly affects clinical outcomes, patient satisfaction, and health-care expenditure. Numerous studies have revealed venous injuries only through visual and histopathological examination. Although sporadic studies have explored the cellular and molecular biological mechanisms of phlebitis and the outcomes of pharmacological interventions, an updated review over the last decade is not available.
METHODS
Progress in research on the mechanisms and interventions of phlebitis was summarized from the perspective of endothelial cells and signaling pathways by retrieving the PubMed, Web of Science Core Collection, MEDLINE, Embase, and CNKI.
RESULTS
Phlebitis involves multiple signaling pathways (eg, nuclear factor kappa B, Wnt/β-catenin, focal adhesion kinase/protein kinase B, Toll-like receptor, protein kinase C beta/NADPH oxidase, PI3K/AKT/TNF, and JAK2/STAT3), upregulation of E-selectin, GBP5/NLRP3 inflammasome axis, cell apoptosis, intracellular ROS generation, SOD reduction, stimulation of angiogenesis, and induction of autophagy-associated cell death. Preventive and curative interventions included α-solanine, baicalein, escin, intermedin, Y15, micro-ribonucleic acid-223, sotrastaurin, cimetidine, aescin, resveratrol, α-chaconine, Chahuang ointment, QingLuoTongMai, Mailuo Shutong, and N-acetylcysteine. Laboratory models included vascular endothelial cells, real-time cell-monitoring analysis, network pharmacology analysis and experimental verification in vivo, animal models of phlebitis (rat, rabbit, and mouse), rabbit models with peripherally inserted central catheters (PICC) catheterization, models of PICC/central venous catheter indwelling with combined drugs in human umbilical vein endothelial cells, and compatibility with endothelial cells. Factors affecting vascular endothelial cell injury include difference in the same class of drugs, concentration and exposure time of precipitant, and infusion strategy.
CONCLUSION
Phlebitis is accompanied by endothelial dysfunction and may involve multiple molecular and cellular mechanisms. These findings improve our understanding of the molecular targets of interventions and help identify effective candidates for the prophylaxis and treatment of phlebitis. Vascular health and risk management should be considered when initiating intravenous administration.
PubMed: 38170089
DOI: 10.2147/JIR.S450149