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1.
Clin Neurol Neurosurg ; 201: 106440, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33383464

RESUMO

BACKGROUND AND IMPORTANCE: Additional time is needed to determine the exact impact of COVID-19 on acute cerebrovascular disease incidence, but recently published data has correlated COVID-19 to large vessel occlusion strokes. CLINICAL PRESENTATION: We report the first case of central retinal artery occlusion (CRAO) as the initial manifestation of COVID-19 infection. Subsequent neuroimaging revealed a large thrombus extending into the internal carotid artery. CONCLUSION: This case illustrates the need to suspect COVID-19 infection in patients presenting with retinal arterial occlusion, including individuals who are asymptomatic or minimally symptomatic for COVID-19 infection.


Assuntos
/diagnóstico por imagem , Oclusão da Artéria Retiniana/diagnóstico por imagem , Transtornos da Visão/diagnóstico por imagem , Visão Monocular/fisiologia , /complicações , Diagnóstico Diferencial , Humanos , Masculino , Pessoa de Meia-Idade , Oclusão da Artéria Retiniana/etiologia , Transtornos da Visão/etiologia
2.
J Neurosci ; 40(27): 5214-5227, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32467358

RESUMO

The limitation of plasticity in the adult brain impedes functional recovery later in life from brain injury or disease. This pressing clinical issue may be resolved by enhancing plasticity in the adult brain. One strategy for triggering robust plasticity in adulthood is to reproduce one of the hallmark physiological events of experience-dependent plasticity observed during the juvenile critical period: to rapidly reduce the activity of parvalbumin (PV)-expressing interneurons and disinhibit local excitatory neurons. This may be achieved through the enhancement of local inhibitory inputs, particularly those of somatostatin (SST)-expressing interneurons. However, to date the means for manipulating SST interneurons for enhancing cortical plasticity in the adult brain are not known. We show that SST interneuron-selective overexpression of Lypd6, an endogenous nicotinic signaling modulator, enhances ocular dominance plasticity in the adult primary visual cortex (V1). Lypd6 overexpression mediates a rapid experience-dependent increase in the visually evoked activity of SST interneurons as well as a simultaneous reduction in PV interneuron activity and disinhibition of excitatory neurons. Recapitulating this transient activation of SST interneurons using chemogenetics similarly enhanced V1 plasticity. Notably, we show that SST-selective Lypd6 overexpression restores visual acuity in amblyopic mice that underwent early long-term monocular deprivation. Our data in both male and female mice reveal selective modulation of SST interneurons and a putative downstream circuit mechanism as an effective method for enhancing experience-dependent cortical plasticity as well as functional recovery in adulthood.SIGNIFICANCE STATEMENT The decline of cortical plasticity after closure of juvenile critical period consolidates neural circuits and behavior, but this limits functional recovery from brain diseases and dysfunctions in later life. Here we show that activation of cortical somatostatin (SST) interneurons by Lypd6, an endogenous modulator of nicotinic acetylcholine receptors, enhances experience-dependent plasticity and recovery from amblyopia in adulthood. This manipulation triggers rapid reduction of PV interneuron activity and disinhibition of excitatory neurons, which are known hallmarks of cortical plasticity during juvenile critical periods. Our study demonstrates modulation of SST interneurons by Lypd6 to achieve robust levels of cortical plasticity in the adult brain and may provide promising targets for restoring brain function in the event of brain trauma or disease.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Proteínas Ligadas por GPI/fisiologia , Interneurônios/fisiologia , Plasticidade Neuronal/fisiologia , Somatostatina/fisiologia , Córtex Visual/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Dominância Ocular/genética , Potenciais Evocados Visuais/genética , Potenciais Evocados Visuais/fisiologia , Feminino , Proteínas Ligadas por GPI/genética , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Plasticidade Neuronal/genética , Fosfatidilinositóis/farmacologia , Receptores Nicotínicos/genética , Recuperação de Função Fisiológica/genética , Visão Monocular/genética , Visão Monocular/fisiologia , Acuidade Visual/genética
3.
Sci Rep ; 10(1): 7205, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350337

RESUMO

In birds, like in mammals, the hippocampus is particularly sensitive to exposure to novel environments, a function that is based on visual input. Chicks' eyes are placed laterally and their optic fibers project mainly to the contralateral brain hemispheres, with only little direct interhemispheric coupling. Thus, monocular occlusion has been frequently used in chicks to document functional specialization of the two hemispheres. However, we do not know whether monocular occlusion influences hippocampal activation. The aim of the present work was to fill this gap by directly testing this hypothesis. To induce hippocampal activation, chicks were exposed to a novel environment with their left or right eye occluded, or in conditions of binocular vision. Their hippocampal expression of c-Fos (neural activity marker) was compared to a baseline group that remained in a familiar environment. Interestingly, while the hippocampal activation in the two monocular groups was not different from the baseline, it was significantly higher in the binocular group exposed to the novel environment. This suggest that the representation of environmental novelty in the hippocampus of domestic chicks involves strong binocular integration.


Assuntos
Proteínas Aviárias/metabolismo , Hipocampo/fisiologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Percepção Espacial/fisiologia , Visão Monocular/fisiologia , Animais , Galinhas , Visão Binocular/fisiologia
4.
Invest Ophthalmol Vis Sci ; 61(4): 44, 2020 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-32343785

RESUMO

Purpose: To determine how visual cortex plasticity changes after monocular deprivation (MD) in mice and whether conventional protein kinase C gamma (cPKCγ) plays a role in visual cortex plasticity. Methods: cPKCγ membrane translocation levels were quantified by using immunoblotting to explore the effects of MD on cPKCγ activation. Electrophysiology was used to record field excitatory postsynaptic potential (fEPSP) amplitude with the goal of observing changes in visual cortex plasticity after MD. Immunoblotting was also used to determine the phosphorylation levels of GluR1 at Ser831. Light transmission was analyzed using electroretinography to examine the effects of MD and cPKCγ on mouse retinal function. Results: Membrane translocation levels of cPKCγ significantly increased in the contralateral visual cortex of MD mice compared to wild-type (WT) mice (P < 0.001). In the contralateral visual cortex, long-term potentiation (LTP) and the phosphorylation levels of GluR1 at Ser 831 were increased in cPKCγ+/+ mice after MD. Interestingly, these levels could be downregulated by cPKCγ knockout compared to cPKCγ+/++MD mice (P < 0.001). Compared to the right eyes of WT mice, the amplitudes of a-waves and b-waves declined in deprived right eyes of mice after MD (P < 0.001). There were no significant differences when comparing cPKCγ+/+ and cPKCγ-/- mice with MD. Conclusions: cPKCγ participates in the plasticity of the visual cortex after MD, which is characterized by increased LTP in the contralateral visual cortex, which may be a result of cPKCγ-mediated phosphorylation of GluR1 at Ser 831.


Assuntos
Plasticidade Neuronal , Proteína Quinase C/genética , Receptores de AMPA/genética , Privação Sensorial , Visão Monocular/fisiologia , Análise de Variância , Animais , Modelos Animais de Doenças , Eletrorretinografia , Feminino , Imunofluorescência , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação/genética , Proteína Quinase C-épsilon/genética , Distribuição Aleatória , Transmissão Sináptica , Córtex Visual/fisiologia , Vias Visuais/fisiologia
5.
Sci Rep ; 10(1): 4946, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-32188906

RESUMO

Contrast sensitivity is mostly used as a tool for testing aspects of visual functions. Infantile nystagmus is a pathological phenomenon that affects the spatial-temporal visual functions due to spontaneous oscillating movements of the eyes. We examined the spatial-temporal aspects of nystagmus perception, aiming to investigate the mechanisms underlying the deterioration of their visual performance. We tested the monocular and binocular contrast sensitivity of nystagmus and normally sighted subjects by measuring contrast detection of a Gabor target with spatial frequencies slightly above the cutoff threshold of each subject (nystagmus ~3; controls = 9cpd; presentation times 60-480 ms). The dominant eye of nystagmus revealed large differences over the non-dominant eye, highlighting the superiority of the dominant over the non-dominant eye in nystagmus. In addition, binocular summation mechanism was impaired in majority of the nystagmus subjects. Furthermore, these differences are not attributed to differences in visual acuity. Moreover, the visual performance in nystagmus continue to improve for longer presentation time compared with controls and was longer in the poor eye. Since the results are not due to differences in eye movements and strabismus, we suggest that the differences are due to developmental impairment in the visual system during the critical period.


Assuntos
Movimentos Oculares , Nistagmo Congênito/fisiopatologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Percepção Visual , Adolescente , Adulto , Pré-Escolar , Sensibilidades de Contraste , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Acuidade Visual , Adulto Jovem
6.
J Vis ; 20(2): 6, 2020 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-32097484

RESUMO

We investigated the relationship between eyes receiving visual input of large field translating random dot motion and subsequent reflexive changes in running direction in mice. The animals were head-fixed running on a Styrofoam ball and the opto-locomotor reflex (OLR) was measured in response to 2 s of dots patterns moving horizontally to the left or right. We measured the OLR in conditions with both eyes open (binocular) and one eye closed (monocular). When we covered the right or left eye in the monocular condition, we found reflexive behavior to be delayed for a few hundred milliseconds to leftward or rightward motion, respectively. After this delay, the bias disappeared and reflexive behavior was similar to responses to motion under binocular conditions. These results might be explained by different contributions of subcortical and cortical visual motion processing pathways to the OLR. Furthermore, we found no evidence for nonlinear interactions between the two eyes, because the sum of the OLR of the two monocular conditions was equal in amplitude and temporal characteristics to the OLR under binocular conditions.


Assuntos
Locomoção/fisiologia , Percepção de Movimento/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Vias Visuais/fisiologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Reflexo Vestíbulo-Ocular/fisiologia
8.
Am J Ophthalmol ; 212: 105-115, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31765626

RESUMO

PURPOSE: We report the visual outcomes and patient satisfaction after bilateral implantation of a bifocal diffractive intraocular lens with monovision. DESIGN: Prospective, observational case series. METHODS: Twenty-one subjects underwent cataract surgery or refractive lens exchange with bilateral implantation of the ZMB00 intraocular lens, with the dominant eye and nondominant eye targeted for plano and -1.25 to -1.00 diopters, respectively. Postoperative assessments included visual acuity (VA) at various distances under photopic and mesopic conditions; defocus curve, contrast sensitivity, and stereopsis; and Visual Function Questionnaire-25 and supplementary questionnaire. RESULTS: Mean binocular uncorrected VA at distance, intermediate (67 cm), and near (30 cm) were -0.03 ± 0.06, 0.12 ± 0.18, and 0.11 ± 0.05, respectively. No eyes lost >1 line of corrected distance VA. Binocular intermediate VA was significantly better in the uncorrected condition (P = .004) whereas binocular distance VA was better in the distance-corrected condition (P = .014). Near VA was similar in both conditions (P > .05). Stereoacuity and contrast sensitivity were within normal limits. All subjects had a composite score of ≥90 for vision-targeted items in the National Eye Institute Visual Function Questionnaire-25. Halos, glare, and starbursts occurred in 52%, 29%, and 24% of subjects, respectively. All subjects reported a satisfaction score of ≥3.5 of 5 and required no spectacles postoperatively. No intraocular lens exchange was required. CONCLUSIONS: Monovision with bilateral bifocal multifocal intraocular lens was safe and provided satisfactory vision at various distances, with good stereopsis and contrast sensitivity. Complete spectacle independence and high satisfaction score were achieved. In comparison with bilateral emmetropic bifocal multifocal intraocular lens, it provided better vision at intermediate and at very near distances without inducing more dysphotopsia.


Assuntos
Lentes Intraoculares Multifocais , Presbiopia/cirurgia , Visão Monocular/fisiologia , Idoso , Catarata/fisiopatologia , Catarata/psicologia , Extração de Catarata/psicologia , Feminino , Humanos , Implante de Lente Intraocular/psicologia , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Cuidados Pós-Operatórios , Presbiopia/fisiopatologia , Presbiopia/psicologia , Estudos Prospectivos , Refração Ocular/fisiologia , Resultado do Tratamento , Acuidade Visual/fisiologia
9.
J Neurosci ; 40(3): 585-604, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31767678

RESUMO

Study of the neural deficits caused by mismatched binocular vision in early childhood has predominantly focused on circuits in the primary visual cortex (V1). Recent evidence has revealed that neurons in mouse dorsolateral geniculate nucleus (dLGN) can undergo rapid ocular dominance plasticity following monocular deprivation (MD). It remains unclear, however, whether the long-lasting deficits attributed to MD during the critical period originate in the thalamus. Using in vivo two-photon Ca2+ imaging of dLGN afferents in superficial layers of V1 in female and male mice, we demonstrate that 14 d MD during the critical period leads to a chronic loss of binocular dLGN inputs while sparing response strength and spatial acuity. Importantly, MD leads to profoundly mismatched visual tuning properties in remaining binocular dLGN afferents. Furthermore, MD impairs binocular modulation, reducing facilitation of responses of both binocular and monocular dLGN inputs during binocular viewing. As predicted by our findings in thalamic inputs, Ca2+ imaging from V1 neurons revealed spared spatial acuity but impaired binocularity in L4 neurons. V1 L2/3 neurons in contrast displayed deficits in both binocularity and spatial acuity. Our data demonstrate that critical-period MD produces long-lasting disruptions in binocular integration beginning in early binocular circuits in dLGN, whereas spatial acuity deficits first arise from circuits further downstream in V1. Our findings indicate that the development of normal binocular vision and spatial acuity depend upon experience-dependent refinement of distinct stages in the mammalian visual system.SIGNIFICANCE STATEMENT Abnormal binocular vision and reduced acuity are hallmarks of amblyopia, a disorder that affects 2%-5% of the population. It is widely thought that the neural deficits underlying amblyopia begin in the circuits of primary visual cortex. Using in vivo two-photon calcium imaging of thalamocortical axons in mice, we show that depriving one eye of input during a critical period in development chronically impairs binocular integration in thalamic inputs to primary visual cortex. In contrast, visual acuity is spared in thalamic inputs. These findings shed new light on the role for developmental mechanisms in the thalamus in establishing binocular vision and may have critical implications for amblyopia.


Assuntos
Privação Sensorial/fisiologia , Tálamo/crescimento & desenvolvimento , Tálamo/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Visão Ocular/fisiologia , Ambliopia/fisiopatologia , Animais , Mapeamento Encefálico , Feminino , Corpos Geniculados/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estimulação Luminosa , Percepção Espacial , Acuidade Visual/fisiologia , Córtex Visual/fisiologia
10.
Biomed Res Int ; 2019: 3867138, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31815133

RESUMO

Analysis of visually guided tracking movements is an important component of understanding human visuomotor control system. The aim of our study was to investigate the effects of different target speeds and different circular tracking planes, which provide different visual feedback of depth information, on temporal and spatial tracking accuracy. In this study, we analyze motor control characteristic of circular tracking movements during monocular vision in three-dimensional space using a virtual reality system. Three parameters in polar coordinates were analyzed: ΔR, the difference in the distance from the fixed pole; Δθ, the difference in the position angle; and Δω, the difference in the angular velocity. We compare the accuracy of visually guided circular tracking movements during monocular vision in two conditions: (1) movement in the frontal plane relative to the subject that requires less depth information and (2) movement in the sagittal plane relative to the subject that requires more depth information. We also examine differences in motor control at four different target speeds. The results show that depth information affects both spatial and temporal accuracy of circular tracking movement, whereas target speed only affects temporal accuracy of circular tracking movement. This suggests that different strategies of feedforward and feedback controls are performed in the tracking of movements.


Assuntos
Movimentos Oculares/fisiologia , Desempenho Psicomotor/fisiologia , Visão Monocular/fisiologia , Adulto , Fenômenos Biomecânicos , Retroalimentação , Humanos , Masculino , Realidade Virtual , Adulto Jovem
11.
PLoS One ; 14(12): e0226308, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31841526

RESUMO

We performed two experiments to investigate how monocular vision and a monocular generalized reduction in vision (MRV) impact driving performance during racing. A total of 75 visually normal students or professional racing drivers, were recruited for the two experiments. Driving performance was evaluated under three visual conditions: normal vision, simulated monocularity and simulated monocular reduction in vision. During the driving scenario, the drivers had to detect and react to the sudden intrusion of an opponent's racing car into their trajectory when entering a turn. Generalized Linear Mixed Models (GLMMs) and ANOVA were then used to explore how monocular vision and monocular reduction in vision affect drivers' performance (crash and reaction time) while confronting them with critical situations. The results show that drivers under monocular condition are from 2.1 (95% CI 1.11-4.11, p = .024) to 6.5 (95% CI 3.91-11.13; p = .0001) times more likely to collide with target vehicles compared with their baseline (binocular) condition, depending on the driving situation. Furthermore, there was an average increase in reaction time from 64 ms (p = .029) to 126 ms (p = .015) under monocular condition, depending on the critical driving situation configuration. This study objectively demonstrates that monocularity has a significant impact on driving performance and safety during car racing, whereas performance under monocular reduction in vision conditions is less affected.


Assuntos
Condução de Veículo , Tempo de Reação/fisiologia , Visão Monocular/fisiologia , Acuidade Visual/fisiologia , Aceleração , Acidentes de Trânsito , Adolescente , Adulto , Desempenho Atlético/fisiologia , Feminino , França , Humanos , Masculino , Esportes/fisiologia , Transtornos da Visão/fisiopatologia , Visão Binocular/fisiologia , Testes de Campo Visual , Campos Visuais/fisiologia , Adulto Jovem
12.
Vis Neurosci ; 36: E012, 2019 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-31718727

RESUMO

In primates and carnivores, the main laminae of the dorsal lateral geniculate nucleus (LGN) receive monocular excitatory input in an eye-alternating fashion. There is also evidence that nondominant eye stimulation can reduce responses to dominant eye stimulation and that a subset of LGN cells in the koniocellular (K) layers receives convergent binocular excitatory input from both eyes. What is not known is how the two eye inputs summate in the K layers of LGN. Here, we aimed to answer this question by making extracellular array electrode recordings targeted to K layers in the marmoset (Callithrix jacchus) LGN, as visual stimuli (flashed 200 ms temporal square-wave pulses or drifting gratings) were presented to each eye independently or to both eyes simultaneously. We found that when the flashed stimulus was presented to both eyes, compared to the dominant eye, the peak firing rate of most cells (61%, 14/23) was reduced. The remainder showed response facilitation (17%) or partial summation (22%). A greater degree of facilitation was seen when the total number of spikes across the stimulus time window (200 ms) rather than peak firing rates was measured. A similar pattern of results was seen for contrast-varying gratings and for small numbers of parvocellular (n = 12) and magnocellular (n = 3) cells recorded. Our findings show that binocular summation in the marmoset LGN is weak and predominantly sublinear in nature.


Assuntos
Callithrix/fisiologia , Fenômenos Eletrofisiológicos/fisiologia , Corpos Geniculados/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Animais , Estimulação Luminosa
13.
Invest Ophthalmol Vis Sci ; 60(14): 4858-4864, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31747686

RESUMO

Purpose: We investigate temporal synchrony within one eye and between both eyes in adults with amblyopia. Methods: Eight adult amblyopes (range, 19.88-27.81 years old; median, 22.86 years old) and 12 age-matched adults with normal vision (range, 21.2-50.30 years old; median, 23.78 years old) participated in the experiment. We showed two pairs of Gaussian blobs flickering at 1 Hz as visual stimuli, one pair with the same temporal phase modulation (i.e., the reference) and another pair with a distinct temporal phase (i.e., the signal). We employed the constant stimuli method to measure the minimum degree of temporal phase (temporal synchrony threshold), at which participants were able to discriminate the signal pair under binocular, monocular, and dichoptic viewing configurations. Results: The temporal synchrony threshold was different across the six configurations (P = 0.001). There was also an interaction between the configuration and the group (P = 0.004). The synchrony threshold was significantly higher in amblyopes than in controls under the configurations where two pairs of blobs were presented to the amblyopic eye (136.52 ± 50.19 vs. 97.08 ± 22.02 ms, P = 0.027) and where the paired blobs were presented to different eyes (163.15 ± 80.85 vs. 111.61 ± 22.46 ms, P = 0.049). The visual deficits in these two configurations were significantly correlated (r = 0.824, P = 0.012). Conclusions: The threshold for detecting temporal asynchrony increased when the stimuli were presented only to the amblyopic eye and when they were dichoptically presented to the amblyopic and fellow eyes.


Assuntos
Ambliopia/fisiopatologia , Transtornos da Percepção/fisiopatologia , Limiar Sensorial/fisiologia , Visão Binocular/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Percepção de Movimento/fisiologia , Percepção Espacial/fisiologia , Análise Espaço-Temporal , Visão Monocular/fisiologia , Acuidade Visual/fisiologia , Adulto Jovem
14.
Neural Plast ; 2019: 2564018, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31565045

RESUMO

Monocular deprivation (MD) during the critical period (CP) has enduring effects on visual acuity and the functioning of the visual cortex (V1). This experience-dependent plasticity has become a model for studying the mechanisms, especially glutamatergic and GABAergic receptors, that regulate amblyopia. Less is known, however, about treatment-induced changes to those receptors and if those changes differentiate treatments that support the recovery of acuity versus persistent acuity deficits. Here, we use an animal model to explore the effects of 3 visual treatments started during the CP (n = 24, 10 male and 14 female): binocular vision (BV) that promotes good acuity versus reverse occlusion (RO) and binocular deprivation (BD) that causes persistent acuity deficits. We measured the recovery of a collection of glutamatergic and GABAergic receptor subunits in the V1 and modeled recovery of kinetics for NMDAR and GABAAR. There was a complex pattern of protein changes that prompted us to develop an unbiased data-driven approach for these high-dimensional data analyses to identify plasticity features and construct plasticity phenotypes. Cluster analysis of the plasticity phenotypes suggests that BV supports adaptive plasticity while RO and BD promote a maladaptive pattern. The RO plasticity phenotype appeared more similar to adults with a high expression of GluA2, and the BD phenotypes were dominated by GABAA α1, highlighting that multiple plasticity phenotypes can underlie persistent poor acuity. After 2-4 days of BV, the plasticity phenotypes resembled normals, but only one feature, the GluN2A:GluA2 balance, returned to normal levels. Perhaps, balancing Hebbian (GluN2A) and homeostatic (GluA2) mechanisms is necessary for the recovery of vision.


Assuntos
Ambliopia/fisiopatologia , Plasticidade Neuronal/fisiologia , Receptores de GABA-A/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Córtex Visual/fisiopatologia , Ambliopia/metabolismo , Ambliopia/terapia , Animais , Gatos , Modelos Animais de Doenças , Feminino , Masculino , Neurônios/metabolismo , Fenótipo , Privação Sensorial/fisiologia , Acuidade Visual/fisiologia , Córtex Visual/metabolismo
15.
Proc Natl Acad Sci U S A ; 116(43): 21812-21820, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31591211

RESUMO

The developing brain can respond quickly to altered sensory experience by circuit reorganization. During a critical period in early life, neurons in the primary visual cortex rapidly lose responsiveness to an occluded eye and come to respond better to the open eye. While physiological and some of the molecular mechanisms of this process have been characterized, its structural basis, except for the well-known changes in the thalamocortical projection, remains obscure. To elucidate the relationship between synaptic remodeling and functional changes during this experience-dependent process, we used 2-photon microscopy to image synaptic structures of sparsely labeled layer 2/3 neurons in the binocular zone of mouse primary visual cortex. Anatomical changes at presynaptic and postsynaptic sites in mice undergoing monocular visual deprivation (MD) were compared to those in control mice with normal visual experience. We found that postsynaptic spines remodeled quickly in response to MD, with neurons more strongly dominated by the deprived eye losing more spines. These postsynaptic changes parallel changes in visual responses during MD and their recovery after restoration of binocular vision. In control animals with normal visual experience, the formation of presynaptic boutons increased during the critical period and then declined. MD affected bouton formation, but with a delay, blocking it after 3 d. These findings reveal intracortical anatomical changes in cellular layers of the cortex that can account for rapid activity-dependent plasticity.


Assuntos
Ambliopia/fisiopatologia , Plasticidade Neuronal/fisiologia , Córtex Visual/embriologia , Vias Visuais/embriologia , Animais , Camundongos , Camundongos Endogâmicos C57BL , Terminações Pré-Sinápticas/fisiologia , Privação Sensorial/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Córtex Visual/fisiologia
16.
J. optom. (Internet) ; 12(3): 192-197, jul.-sept. 2019. tab, graf
Artigo em Inglês | IBECS | ID: ibc-185370

RESUMO

Purpose: Visual evoked potentials (VEPs) provide important diagnostic information related to the functional integrity of the visual pathways. The aim of this study was to establish normative values of different components of pattern reversal VEPs on Iranian normal adult subjects. Methods: Monocular and binocular pattern reversal VEPs were recorded on 59 healthy participants (22.55 ± 3.79 years old) using the Roland RETI system for two check sizes of 15 and 60 min of arc. The measured VEP components were the latencies of N75, P100, N135 and amplitude of N75-P100. Results: Repeated measures ANOVA showed that viewing eye condition has a significant impact on the amplitude of N75-P100 (P < 0.001, F = 13.89). Also, the effect of check size on the latencies of N75, P100, N135, amplitude of N75-P100 (P ≤ 0.010), as well as the intraocular difference of P100 latency and amplitude N75-P100 (P = 0.007) was significant. More specifically, the amplitude of N75-P100 in both check sizes significantly differed between gender groups (P < 0.023). Conclusion: According to the results of this study, VEPs components are affected by the stimulus size, monocular and binocular recording conditions and gender. Therefore, it is necessary to determine the normative values of VEPs in each population, so that the results could be used in clinical studies


Objetivo: Los potenciales evocados visuales (PEV) aportan información diagnóstica importante relacionada con la integridad funcional de las vías visuales. El objetivo de este estudio fue establecer los valores normativos de los diferentes componentes de la reversión del patrón de PEV en adultos normales iraníes. Métodos: Se registraron los valores de reversión monocular y binocular del patrón de PEV en 59 participantes sanos (22,55 ± 3,79 años), utilizando el sistema Roland RETI para dos tamaños de comprobación de 15 y 60 min de arco. Los componentes medidos de PEV fueron las latencias de N75, P100, N135 y la amplitud de N75-P100. Resultados: La repetición de las medidas ANOVA reflejó que la situación del ojo de visión tiene un impacto significativo sobre la amplitud de N75-P100 (P < 0,001, F = 13,89). De igual modo, el efecto del tamaño de la comprobación de las latencias de N75, P100, N 135, la amplitud de N75-P100 (P ≤ 0,010), así como la diferencia intraocular de la latencia de P100 y la amplitud de N75-P100 (P = 0,007) fue significativo. Más específicamente, la amplitud de N75-P100 en ambos tamaños de comprobación difirió considerablemente entre los grupos de sexos (P < 0,023). Conclusión: Con arreglo a los resultados de este estudio, los componentes de los PEV se ven afectados por el tamaño del estímulo, las situaciones del registro monocular y binocular, y el sexo. Por tanto, es necesario determinar los valores normativos de los PEV en cada población, para poder utilizar los resultados en estudios clínicos


Assuntos
Humanos , Masculino , Feminino , Adolescente , Adulto Jovem , Adulto , Potenciais Evocados Visuais/fisiologia , Visão Binocular/fisiologia , Vias Visuais/fisiologia , Análise de Variância , Irã (Geográfico) , Tempo de Reação , Valores de Referência , Visão Monocular/fisiologia
17.
Curr Biol ; 29(15): 2586-2592.e4, 2019 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-31353183

RESUMO

Monovision is a common prescription lens correction for presbyopia [1]. Each eye is corrected for a different distance, causing one image to be blurrier than the other. Millions of people have monovision corrections, but little is known about how interocular blur differences affect motion perception. Here, we report that blur differences cause a previously unknown motion illusion that makes people dramatically misperceive the distance and three-dimensional direction of moving objects. The effect occurs because the blurry and sharp images are processed at different speeds. For moving objects, the mismatch in processing speed causes a neural disparity, which results in the misperceptions. A variant of a 100-year-old stereo-motion phenomenon called the Pulfrich effect [2], the illusion poses an apparent paradox: blur reduces contrast, and contrast reductions are known to cause neural processing delays [3-6], but our results indicate that blurry images are processed milliseconds more quickly. We resolve the paradox with known properties of the early visual system, show that the misperceptions can be severe enough to impact public safety, and demonstrate that the misperceptions can be eliminated with novel combinations of non-invasive ophthalmic interventions. The fact that substantial perceptual errors are caused by millisecond differences in processing speed highlights the exquisite temporal calibration required for accurate perceptual estimation. The motion illusion-the reverse Pulfrich effect-and the paradigm we use to measure it should help reveal how optical and image properties impact temporal processing, an important but understudied issue in vision and visual neuroscience.


Assuntos
Percepção de Profundidade , Ilusões , Percepção de Movimento , Presbiopia/terapia , Visão Monocular/fisiologia , Adulto , Feminino , Humanos , Masculino , Movimento (Física) , Adulto Jovem
18.
Prog Brain Res ; 249: 227-234, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31325982

RESUMO

Acquired pendular nystagmus (APN) often occurs in association with the disorders affecting the visual system, such as multiple sclerosis (MS). The proposed mechanisms of APN in MS have been a delayed conduction of the visual information for ocular stabilization and unstable neural integrator for feedback controls. We determined the effects of visual inputs on the nystagmus intensity and the effects of saccades on phase shift of the nystagmus in a patient with monocular pendular nystagmus from MS. In this patient, (1) during binocular viewing in the light, the nystagmus was observed only in the eye with more severe visual loss, (2) the nystagmus disappeared in darkness, (3) monocular viewing with either eye markedly suppressed the nystagmus, (4) the nystagmus decreased when the visual inputs became less asymmetric between the eyes, and (5) saccades resulted in a phase shift of the nystagmus. From these results, we propose that the difference in the visual inputs between the eyes is responsible for monocular APN by disturbing visual integration and increasing instability of the feedback.


Assuntos
Modelos Neurológicos , Esclerose Múltipla Recidivante-Remitente/fisiopatologia , Nistagmo Patológico/fisiopatologia , Neurite Óptica/fisiopatologia , Transtornos da Visão/fisiopatologia , Feminino , Humanos , Pessoa de Meia-Idade , Esclerose Múltipla Recidivante-Remitente/complicações , Nistagmo Patológico/etiologia , Neurite Óptica/complicações , Movimentos Sacádicos/fisiologia , Transtornos da Visão/etiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia
19.
PLoS One ; 14(7): e0218529, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31295259

RESUMO

Binocular rivalry (BR) is a dynamic visual illusion that provides insight into the cortical mechanisms of visual awareness, stimulus selection, and object identification. When dissimilar binocular images cannot be fused, perception switches every few seconds between the left and right eye images. The speed at which individuals switch between alternatives is a stable, partially heritable trait. In order to isolate the monocular and binocular processes that determine the speed of rivalry, we presented stimuli tagged with a different flicker frequency in each eye and applied stimulus-phase locked MEG source imaging. We hypothesized that the strength of the evoked fundamental or intermodulation frequencies would vary when comparing Fast and Slow Switchers. Ten subjects reported perceptual alternations, with mean dominance durations between 1.2-4.0 sec. During BR, event-related monocular input in V1, and broadly in higher-tier ventral temporal cortex, waxed and waned with the periods of left or right eye dominance/suppression. In addition, we show that Slow Switchers produce greater evoked intermodulation frequency responses in a cortical network composed of V1, lateral occipital, posterior STS, retrosplenial & superior parietal cortices. Importantly, these dominance durations were not predictable from the brain responses to either of the fundamental tagging frequencies in isolation, nor from any responses to a pattern rivalry control condition, or a non-rivalrous control. The novel cortical network isolated, which overlaps with the default-mode network, may contain neurons that compute the level of endogenous monocular difference, and monitor accumulation of this conflict over extended periods of time. These findings are the first to relate the speed of rivalry across observers to the 'efficient coding' theory of computing binocular differences that may apply to binocular vision generally.


Assuntos
Córtex Cerebral/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa
20.
Neuron ; 103(1): 118-132.e7, 2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31147153

RESUMO

Animals use global image motion cues to actively stabilize their position by compensatory movements. Neurons in the zebrafish pretectum distinguish different optic flow patterns, e.g., rotation and translation, to drive appropriate behaviors. Combining functional imaging and morphological reconstruction of single cells, we revealed critical neuroanatomical features of this sensorimotor transformation. Terminals of direction-selective retinal ganglion cells (DS-RGCs) are located within the pretectal retinal arborization field 5 (AF5), where they meet dendrites of pretectal neurons with simple tuning to monocular optic flow. Translation-selective neurons, which respond selectively to optic flow in the same direction for both eyes, are intermingled with these simple cells but do not receive inputs from DS-RGCs. Mutually exclusive populations of pretectal projection neurons innervate either the reticular formation or the cerebellum, which in turn control motor responses. We posit that local computations in a defined pretectal circuit transform optic flow signals into neural commands driving optomotor behavior. VIDEO ABSTRACT.


Assuntos
Fluxo Óptico/fisiologia , Vias Visuais/citologia , Animais , Cerebelo/citologia , Cerebelo/fisiologia , Dendritos/fisiologia , Neurópilo/fisiologia , Neurópilo/ultraestrutura , Terminações Pré-Sinápticas/fisiologia , Formação Reticular/citologia , Formação Reticular/fisiologia , Células Ganglionares da Retina/fisiologia , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Vias Visuais/anatomia & histologia , Peixe-Zebra/fisiologia
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