RESUMEN
We investigated whether adaptation from implied motion (IM) is transferred to real motion using optokinetic nystagmus (OKN) in infants. Specifically, we examined whether viewing a series of images depicting motion shifted infants' OKN responses to the opposite direction of random dot kinematograms (RDKs). Each RDK was presented 10 times in a pre-test, followed by 10 trials of IM adaptation and test. During the pre-test, the signal dots of the RDK moved left or right. During IM adaptation, 10 randomly selected images depicting leftward (or rightward) IM were presented. In the test, the RDK was presented immediately after the last IM image. An observer, blinded to the motion direction, assessed the OKN direction. The number of matches in OKN responses for each RDK direction was calculated as the match ratio of OKN. We conducted a two-way mixed analysis of variance, with age group (5-6 months and 7-8 months) as the between-participant factor and adaptation (pre-test and test) as the within-participant factor. Only in 7-8 months the OKN responses were shifted in the opposite direction of RDK by viewing a series of images depicting motion, and these infants could detect both IM and RDK motion directions in the pre-test. Our results indicate that detecting the IM and RDK directions might induce direction-selective adaptation in 7-8 months.
Asunto(s)
Adaptación Fisiológica , Percepción de Movimiento , Nistagmo Optoquinético , Estimulación Luminosa , Humanos , Percepción de Movimiento/fisiología , Lactante , Estimulación Luminosa/métodos , Nistagmo Optoquinético/fisiología , Adaptación Fisiológica/fisiología , Masculino , FemeninoRESUMEN
Our previous studies have shown the benefit of intravitreal injection of a mesenchymal stem cell (MSC)- derived secretome to treat visual deficits in a mild traumatic brain injury (mTBI) mouse model. In this study, we have addressed whether MSC-derived extracellular vesicles (EV) overexpressing miR424, which particularly targets neuroinflammation, show similar benefits in the mTBI model. Adult C57BL/6 mice were subjected to a 50-psi air pulse on the left side, overlying the forebrain, resulting in mTBI. Sham-blast mice were controls. Within an hour of blast injury, 3 µl (â¼7.5 × 108 particles) of miR424-EVs, native-EVs, or saline was delivered intravitreally. One month later, retinal morphology was observed through optical coherence tomography (OCT); visual function was assessed using optokinetic nystagmus (OKN) and electroretinogram (ERG), followed by immunohistological analysis. A separate study in adult mice tested the dose-response of EVs for safety. Blast injury mice with saline showed decreased visual acuity compared with the sham group (0.30 ± 0.03 vs. 0.39 ± 0.01 c/d, p < 0.02), improved with miR424-EVs (0.39 ± 0.02 c/d, p < 0.01) but not native-EVs (0.33 ± 0.04 c/d, p > 0.05). Contrast sensitivity thresholds of blast mice receiving saline increased compared with the sham group (85.3 ± 5.9 vs. 19.9 ± 4.8, %, p < 0.001), rescued by miR424-EVs (23.6 ± 7.3 %, p < 0.001) and native-EVs (45.6 ± 10.7 %, p < 0.01). Blast injury decreased "b" wave amplitude compared to sham mice (94.6 ± 24.0 vs. 279.2 ± 25.3 µV, p < 0.001), improved with miR424-EVs (173.0 ± 27.2 µV, p < 0.03) and native-EVs (230.2 ± 37.2 µV, p < 0.01) with a similar decrease in a-wave amplitude in blast mice improved with both miR424-EVs and native-EVs. Immunohistology showed increased GFAP and IBA1 in blast mice with saline compared with sham (GFAP: 11.9 ± 1.49 vs. 9.1 ± 0.8, mean intensity/100,000 µm2 area, p < 0.03; IBA1: 36.08 ± 4.3 vs. 24.0 ± 1.54, mean intensity/100,000 µm2 area, p < 0.01), with no changes with native-EVs (GFAP: 12.6 ± 0.79, p > 0.05; IBA1: 32.8 ± 2.9, p > 0.05), and miR424-EV (GFAP: 13.14 ± 0.76, p > 0.05; IBA1: 31.4 ± 2.7, p > 0.05). Both native-EVs and miR424-EVs exhibited vitreous aggregation, as evidenced by particulates in the vitreous by OCT, and increased vascular structures, as evidenced by αSMA and CD31 immunostainings. The number of capillary lumens in the ganglion cell layer increased with increased particles in the eye, with native EVs showing the worst effects. In conclusion, our study highlights the promise of EV-based therapies for treating visual dysfunction caused by mTBI, with miR424-EVs showing particularly strong neuroprotective benefits. Both miR424-EVs and native-EVs provided similar protection, but issues with EV aggregation and astrogliosis or microglial/macrophage activation at the current dosage call for improved delivery methods and dosage adjustments. Future research should investigate the mechanisms behind EVs' effects and optimize miR424 delivery strategies to enhance therapeutic outcomes and reduce complications.
Asunto(s)
Traumatismos por Explosión , Modelos Animales de Enfermedad , Electrorretinografía , Vesículas Extracelulares , Células Madre Mesenquimatosas , Ratones Endogámicos C57BL , MicroARNs , Tomografía de Coherencia Óptica , Animales , Vesículas Extracelulares/metabolismo , Ratones , MicroARNs/genética , Traumatismos por Explosión/terapia , Traumatismos por Explosión/fisiopatología , Traumatismos por Explosión/metabolismo , Traumatismos por Explosión/complicaciones , Células Madre Mesenquimatosas/metabolismo , Masculino , Nistagmo Optoquinético/fisiología , Inyecciones Intravítreas , Agudeza Visual/fisiología , Trastornos de la Visión/fisiopatología , Trastornos de la Visión/etiología , Trastornos de la Visión/terapia , Trasplante de Células Madre Mesenquimatosas/métodosRESUMEN
Eye-tracking techniques have gained widespread application in various fields including research on the visual system, neurosciences, psychology, and human-computer interaction, with emerging clinical implications. In this preliminary phase of our study, we introduce a pilot test of innovative virtual reality technology designed for tracking head and eye movements among healthy individuals. This tool was developed to assess the presence of mild traumatic brain injury (mTBI), given the frequent association of oculomotor function deficits with such injuries. Alongside eye-tracking, we also integrated fMRI due to the complementary nature of these techniques, offering insights into both neural activation patterns and behavioural responses, thereby providing a comprehensive understanding of oculomotor function. We used fMRI with tasks evaluating oculomotor functions: Smooth Pursuit (SP), Saccades, Anti-Saccades, and Optokinetic Nystagmus (OKN). Prior to the scanning, the testing with a system of VR goggles with integrated eye and head tracking was used where subjects performed the same tasks as those used in fMRI. 31 healthy adult controls (HCs) were tested with the purpose of identifying brain regions associated with these tasks and collecting preliminary norms for later comparison with concussed subjects. HCs' fMRI results showed following peak activation regions: SP-cuneus, superior parietal lobule, paracentral lobule, inferior parietal lobule (IPL), cerebellartonsil (CT); Saccades-middle frontal gyrus (MFG), postcentral gyrus, medial frontal gyrus; Anti-saccades-precuneus, IPL, MFG; OKN-middle temporal gyrus, ACC, postcentral gyrus, MFG, CT. These results demonstrated brain regions associated with the performance on oculomotor tasks in healthy controls and most of the highlighted areas are corresponding with those affected in concussion. This suggests that the involvement of brain areas susceptible to mTBI in implementing oculomotor evaluation, taken together with commonly reported oculomotor difficulties post-concussion, may lead to finding objective biomarkers using eye-tracking tasks.
Asunto(s)
Tecnología de Seguimiento Ocular , Imagen por Resonancia Magnética , Humanos , Imagen por Resonancia Magnética/métodos , Proyectos Piloto , Adulto , Masculino , Femenino , Movimientos Oculares/fisiología , Movimientos Sacádicos/fisiología , Adulto Joven , Seguimiento Ocular Uniforme/fisiología , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Encéfalo/fisiología , Persona de Mediana Edad , Nistagmo Optoquinético/fisiologíaRESUMEN
This case report presents a rare case of infantile nystagmus syndrome (INS) in which the direction of infantile nystagmus (IN) was vertical. A 66-year-old woman was referred to our department for investigation of abnormal eye movements. She showed a disordered field of view with a homonymous hemianopia in the lower left quadrant and vertical gaze-evoked nystagmus, but there were no other abnormal neurological findings. She did not complain of an oscillopsia. Imaging revealed that the cause of hemianopia was atrophy and low cerebral blood flow in the right occipital lobe. The vertical nystagmus became strong when attempting to fixate to stationary targets. A reversed optokinetic nystagmus response was observed in the vertical optokinetic nystagmus test. From these eye movements, we diagnosed her nystagmus as vertical IN. Patients with INS see everything by saccades. IN consists of the alternate appearance of saccades and preceding slow eye movements. For these eye movements, a wide visual field is necessary. In this case, vertical IN was caused by the wider vertical than horizontal visual field resulting from homonymous hemianopia. Therefore, the direction of IN is horizontal in most patients with INS because their horizontal visual field is the widest field.
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Hemianopsia , Nistagmo Congénito , Campos Visuales , Humanos , Femenino , Anciano , Hemianopsia/fisiopatología , Hemianopsia/etiología , Nistagmo Congénito/fisiopatología , Campos Visuales/fisiología , Imagen por Resonancia Magnética , Lóbulo Occipital/fisiopatología , Lóbulo Occipital/diagnóstico por imagen , Nistagmo Optoquinético/fisiología , Movimientos Sacádicos/fisiología , Atrofia , Nistagmo Patológico/fisiopatologíaRESUMEN
BACKGROUND: Multiple system atrophy (MSA) is a neurodegenerative disease that progresses rapidly and has a poor prognosis. This study aimed to assess the value of video oculomotor evaluation (VOE) in the differential diagnosis of MSA and Parkinson's disease (PD). METHODS: In total, 28 patients with MSA, 31 patients with PD, and 30 age- and sex-matched healthy controls (HC) were screened and included in this study. The evaluation consisted of a gaze-holding test, smooth pursuit eye movement (SPEM), random saccade, and optokinetic nystagmus (OKN). RESULTS: The MSA and PD groups had more abnormalities and decreased SPEM gain than the HC group (64.29%, 35.48%, 10%, p < .001). The SPEM gain in the MSA group was significantly lower than that in the PD group at specific frequencies. Patients with MSA and PD showed prolonged latencies in all saccade directions compared with those with HC. However, the two diseases had no significant differences in the saccade parameters. The OKN gain gradually decreased from the HC to the PD and the MSA groups (p < .05). Compared with the PD group, the gain in the MSA group was further decreased in the OKN test at 30°/s (Left, p = .010; Right p = .016). Receiver operating characteristic curves showed that the combination of oculomotor parameters with age and course of disease could aid in the differential diagnosis of patients with MSA and PD, with a sensitivity of 89.29% and a specificity of 70.97%. CONCLUSIONS: The combination of oculomotor parameters and clinical data may aid in the differential diagnosis of MSA and PD. Furthermore, VOE is vital in the identification of neurodegenerative diseases.
Asunto(s)
Atrofia de Múltiples Sistemas , Enfermedad de Parkinson , Movimientos Sacádicos , Humanos , Atrofia de Múltiples Sistemas/diagnóstico , Atrofia de Múltiples Sistemas/fisiopatología , Enfermedad de Parkinson/diagnóstico , Enfermedad de Parkinson/fisiopatología , Masculino , Diagnóstico Diferencial , Femenino , Persona de Mediana Edad , Anciano , Movimientos Sacádicos/fisiología , Grabación en Video , Nistagmo Optoquinético/fisiología , Seguimiento Ocular Uniforme/fisiologíaRESUMEN
OBJECTIVES: To analyse the effectiveness of optokinetic stimulation (OKS) for improving symptoms and function in patients with vestibular and balance disorders. METHODS: PubMed (MEDLINE), SCOPUS, Web of Science (WOS), CINAHL Complete, and PEDro databases were searched to identify randomized controlled trials (RCTs) that included patients with vestibular and balance disorders and compared the effects of OKS versus other interventions or no intervention on subjective or objective functional outcomes. Data were analysed by the standardized mean difference (SMD) and its 95% confidence interval. RESULTS: A total of 10 studies were selected including 468 patients, 177 of whom received OKS. There were no significant differences in scores on the Dizziness Handicap Inventory (DHI) (SMD = 0.02; 95% CI - 0.18 to 0.23; p = 0.83) or the visual analogue scale (VAS) for vertigo (SMD = 0.16; 95% CI - 1.25 to 1.58; p = 0.82). However, there were statistically significant differences in the timed up and go (TUG) test, with a large effect (SMD = - 1.13; 95% CI -2 to - 0.28; p = 0.009), and in the sensory organization test (SOT), with a medium effect (SMD = - 0.7; 95% CI - 1.21 to - 0.19; p = 0.007). Subgroup analysis showed significant effects of OKS on VAS (p = 0.017), TUG (p = 0.009) and SOT (p = 0.001) only in patients with balance disorders without vestibular disease (p > 0.05). CONCLUSIONS: OKS may improve dizziness intensity measured with VAS or dynamic balance measured whit TUG and SOT in patients with balance disorders not due to vestibular disease. The quality of the evidence was low or very low due to the small number of included studies. PROSPERO REGISTRY NUMBER: CRD42023445024.
Asunto(s)
Equilibrio Postural , Enfermedades Vestibulares , Humanos , Equilibrio Postural/fisiología , Enfermedades Vestibulares/terapia , Nistagmo Optoquinético/fisiología , Mareo/terapia , Mareo/etiología , Resultado del TratamientoRESUMEN
The study of behavioral responses to visual stimuli is a key component of understanding visual system function. One notable response is the optokinetic reflex (OKR), a highly conserved innate behavior necessary for image stabilization on the retina. The OKR provides a robust readout of image tracking ability and has been extensively studied to understand visual system circuitry and function in animals from different genetic backgrounds. The OKR consists of two phases: a slow tracking phase as the eye follows a stimulus to the edge of the visual plane and a compensatory fast phase saccade that resets the position of the eye in the orbit. Previous methods of tracking gain quantification, although reliable, are labor intensive and can be subjective or arbitrarily derived. To obtain more rapid and reproducible quantification of eye tracking ability, we have developed a novel semi-automated analysis program, PyOKR, that allows for quantification of two-dimensional eye tracking motion in response to any directional stimulus, in addition to being adaptable to any type of video-oculography equipment. This method provides automated filtering, selection of slow tracking phases, modeling of vertical and horizontal eye vectors, quantification of eye movement gains relative to stimulus speed, and organization of resultant data into a usable spreadsheet for statistical and graphical comparisons. This quantitative and streamlined analysis pipeline, readily accessible via PyPI import, provides a fast and direct measurement of OKR responses, thereby facilitating the study of visual behavioral responses.
Asunto(s)
Tecnología de Seguimiento Ocular , Animales , Nistagmo Optoquinético/fisiología , Movimientos Oculares/fisiologíaRESUMEN
Optokinetic nystagmus (OKN) is a reflexive eye movement in response to movement of the viewer's visual environment that consists of a slow phase eye movement in the direction of the stimulus followed by a quick phase in the opposite direction. When tested at the bedside, the slow phases represent smooth pursuit, while the quick phases represent saccades. Normally, OKN is conjugate and symmetric (horizontally and vertically). Abnormalities in the optokinetic response can provide diagnostic and localising value. We describe six clinical scenarios where OKN testing is most useful for the practising neurologist.
Asunto(s)
Nistagmo Optoquinético , Humanos , Nistagmo Optoquinético/fisiologíaRESUMEN
Purpose: Assessing visual attention and alertness is of great importance in visual and cognitive neuroscience, providing objective measures valuable for both researchers and clinicians. This study investigates how the optokinetic response differs between levels of visual attention in healthy adults while controlling for alertness. Methods: Twelve healthy subjects (8 men and 4 women; mean age = 33 ± 9.36) with intact gaze-stability, visual acuity, and binocularity were recruited. Subjects viewed a rotating visual scene provoking torsional optokinetic nystagmus (OKN) while wearing a video eye tracker in a seated head-fixed position. Tasks requiring focused, neutral, and divided visual attention were issued to each subject and the OKN was recorded. Pupil sizes were monitored as a proxy for alertness. Results: Pupil dilation was increased for both focused and divided visual attention. The number of nystagmus beats was highest for the focused condition and lowest for the divided attentional task. OKN gain was increased during both focused and divided attention. The distribution of nystagmus beats over time showed that only focused attention produced a reliable adaptation of the OKN. Conclusions: Results consequently indicate that OKN frequency is adaptive to a viewer's level of visual attention, whereas OKN gain is influenced by alertness levels. This pattern offers insight into the neural processes integrating visual input with reflexive motor responses. For example, it contextualizes why attention to visual stimuli can cause dizziness, as the OKN frequency reflects activity of the velocity storage mechanism. Additionally, the OKN could offer a possible venue for differentiating between visual attention and alertness during psychometric testing.
Asunto(s)
Adaptación Fisiológica/fisiología , Atención/fisiología , Concienciación/fisiología , Nistagmo Optoquinético/fisiología , Reflejo/fisiología , Percepción Visual/fisiología , Adulto , Femenino , Humanos , Masculino , Valores de ReferenciaRESUMEN
OBJECTIVE: Visual-vestibular mismatch patients experience persistent postural and perceptual dizziness. Previous studies have shown the benefit of vestibular rehabilitation for visual desensitisation using gaze stabilisation exercises and optokinetic stimulation. This study assessed the benefit of customised vestibular rehabilitation with visual desensitisation and virtual reality based therapy rehabilitation in the management of patients with persistent postural-perceptual dizziness. METHODS: This retrospective study included 100 patients with Situational Characteristic Questionnaire scores of more than 0.9. All patients received virtual reality based therapy along with usual vestibular rehabilitation using gaze stabilisation exercises with a plain background followed by graded visual stimulation and optokinetic digital video disc stimulation. Patients' symptoms were assessed before and after vestibular rehabilitation using the Situational Characteristic Questionnaire, Generalised Anxiety Disorder Assessment-7, Nijmegen Questionnaire and Dizziness Handicap Inventory. RESULTS: There were statistically significant improvements in Situational Characteristic Questionnaire scores, Nijmegen Questionnaire scores and Dizziness Handicap Inventory total score. However, there was a statistically insignificant difference in Generalised Anxiety Disorder Assessment-7 scores. There was a significant positive correlation between post-rehabilitation Situational Characteristic Questionnaire scores and other questionnaire results. CONCLUSION: Incorporating virtual reality based therapy with customised vestibular rehabilitation exercises results in significant improvement in persistent postural-perceptual dizziness related symptoms.
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Vértigo Posicional Paroxístico Benigno/diagnóstico , Vértigo Posicional Paroxístico Benigno/rehabilitación , Enfermedades Vestibulares/fisiopatología , Realidad Virtual , Adulto , Vértigo Posicional Paroxístico Benigno/psicología , Terapia por Ejercicio/métodos , Femenino , Fijación Ocular/fisiología , Humanos , Masculino , Persona de Mediana Edad , Nistagmo Optoquinético/fisiología , Estimulación Luminosa/métodos , Propiocepción/fisiología , Estudios Retrospectivos , Autoinforme/estadística & datos numéricos , Encuestas y CuestionariosRESUMEN
Many animals have large visual fields, and sensory circuits may sample those regions of visual space most relevant to behaviours such as gaze stabilisation and hunting. Despite this, relatively small displays are often used in vision neuroscience. To sample stimulus locations across most of the visual field, we built a spherical stimulus arena with 14,848 independently controllable LEDs. We measured the optokinetic response gain of immobilised zebrafish larvae to stimuli of different steradian size and visual field locations. We find that the two eyes are less yoked than previously thought and that spatial frequency tuning is similar across visual field positions. However, zebrafish react most strongly to lateral, nearly equatorial stimuli, consistent with previously reported spatial densities of red, green, and blue photoreceptors. Upside-down experiments suggest further extra-retinal processing. Our results demonstrate that motion vision circuits in zebrafish are anisotropic, and preferentially monitor areas with putative behavioural relevance.
Asunto(s)
Nistagmo Optoquinético/fisiología , Estimulación Luminosa/métodos , Retina/fisiología , Campos Visuales/fisiología , Animales , Femenino , Humanos , Larva/fisiología , Larva/efectos de la radiación , Ratones , Ratones Transgénicos , Nistagmo Optoquinético/efectos de la radiación , Retina/efectos de la radiación , Campos Visuales/efectos de la radiación , Pez CebraRESUMEN
Purpose: To test the hypothesis that acutely correcting a sustained presence of outer retina free radicals measured in vivo in 24-month-old mice corrects their reduced visual performance. Methods: Male C57BL/6J mice two and 24 months old were noninvasively evaluated for unremitted production of paramagnetic free radicals based on whether 1/T1 in retinal laminae are reduced after acute antioxidant administration (QUEnch-assiSTed [QUEST] magnetic resonance imaging [MRI]). Superoxide production was measured in freshly excised retina (lucigenin assay). Combining acute antioxidant administration with optical coherence tomography (i.e., QUEST OCT) tested for excessive free radical-induced shrinkage of the subretinal space volume. Combining antioxidant administration with optokinetic tracking tested for a contribution of uncontrolled free radical production to cone-based visual performance declines. Results: At two months, antioxidants had no effect on 1/T1 in vivo in any retinal layer. At 24 months, antioxidants reduced 1/T1 only in superior outer retina. No age-related change in retinal superoxide production was measured ex vivo, suggesting that free radical species other than superoxide contributed to the positive QUEST MRI signal at 24 months. Also, subretinal space volume did not show evidence for age-related shrinkage and was unresponsive to antioxidants. Finally, visual performance declined with age and was not restored by antioxidants that were effective per QUEST MRI. Conclusions: An ongoing uncontrolled production of outer retina free radicals as measured in vivo in 24 mo C57BL/6J mice appears to be insufficient to explain reductions in visual performance.
Asunto(s)
Antioxidantes/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Radicales Libres/metabolismo , Azul de Metileno/uso terapéutico , Ácido Tióctico/uso terapéutico , Trastornos de la Visión/tratamiento farmacológico , Acridinas/metabolismo , Factores de Edad , Animales , Inyecciones Intraperitoneales , Imagen por Resonancia Magnética , Masculino , Ratones , Ratones Endogámicos C57BL , Nistagmo Optoquinético/fisiología , Retina/diagnóstico por imagen , Retina/enzimología , Superóxidos/metabolismo , Tomografía de Coherencia Óptica , Trastornos de la Visión/diagnóstico por imagen , Trastornos de la Visión/metabolismo , Trastornos de la Visión/fisiopatologíaRESUMEN
Purpose: To describe the derivation of photoreceptor precursor cells from human embryonic stem cells by coculture with RPE cells. Methods: Human embryonic stem cells were induced to differentiate into neural precursor cells and then cocultured with RPE cells to obtain cells showing retinal photoreceptor features. Immunofluorescent staining, reverse transcription-PCR (RT-PCR), and microarray analysis were performed to identify photoreceptor markers, and a cGMP assay was used for in vitro functional analysis. After subretinal injection in rat animal models, retinal function was determined with electroretinography and optokinetic response detection, and immunofluorescent staining was performed to assess the survival of the injected cells. Results: Cocultured cells were positive for rhodopsin, red and blue opsin, recoverin, and phosphodiesterase 6 beta on immunofluorescent staining and RT-PCR. Serial detection of stem cell-, neural precursor-, and photoreceptor-specific markers was noted in each stage of differentiation with microarray analysis. Increased cGMP hydrolysis in light-exposed conditions compared to that in dark conditions was observed. After the subretinal injection in the rats, preservation of optokinetic responses was noted up to 20 weeks, while electroretinographic response decreased. Survival of the injected cells was confirmed with positive immunofluorescence staining of human markers at 8 weeks. Conclusions: Cells showed photoreceptor-specific features when stem cell-derived neurogenic precursors were cocultured with RPE cells.
Asunto(s)
Células Madre Embrionarias Humanas/citología , Células Fotorreceptoras/citología , Epitelio Pigmentado de la Retina/citología , Células Madre/citología , Biomarcadores/metabolismo , Diferenciación Celular/fisiología , Técnicas de Cocultivo , Electrorretinografía , Proteínas del Ojo/metabolismo , Células Madre Embrionarias Humanas/metabolismo , Humanos , Nistagmo Optoquinético/fisiología , Células Fotorreceptoras/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Epitelio Pigmentado de la Retina/metabolismo , Células Madre/metabolismoRESUMEN
When two visual patterns moving in opposite directions are superimposed on the same depth plane, they appear to have two transparent surfaces moving independently (transparent motion). Additionally, the direction of the slow phase of optokinetic nystagmus (OKN) corresponds to the direction of motion that dominates the perceptual appearance. This study examines whether pupil changes correspond to the luminance of the dominated objects related to the transition of the slow-phase direction in OKN following objects. Stimuli consisted of two random dot patterns of different luminance that moved in opposite directions. The results showed that pupil size changed in accordance with the luminance of the pattern in the slow phase of OKN immediately after OKN transition. This suggests that pupil size is modulated with OKN in transparent motion.
Asunto(s)
Percepción de Movimiento , Nistagmo Optoquinético/fisiología , Pupila/efectos de los fármacos , HumanosRESUMEN
We consider a cerebellar ring network for the optokinetic response (OKR), and investigate the effect of diverse recoding of granule (GR) cells on OKR by varying the connection probability pc from Golgi to GR cells. For an optimal value of pc∗(=0.06), individual GR cells exhibit diverse spiking patterns which are in-phase, anti-phase, or complex out-of-phase with respect to their population-averaged firing activity. Then, these diversely-recoded signals via parallel fibers (PFs) from GR cells are effectively depressed by the error-teaching signals via climbing fibers from the inferior olive which are also in-phase ones. Synaptic weights at in-phase PF-Purkinje cell (PC) synapses of active GR cells are strongly depressed via strong long-term depression (LTD), while those at anti-phase and complex out-of-phase PF-PC synapses are weakly depressed through weak LTD. This kind of "effective" depression (i.e., strong/weak LTD) at the PF-PC synapses causes a big modulation in firings of PCs, which then exert effective inhibitory coordination on the vestibular nucleus (VN) neuron (which evokes OKR). For the firing of the VN neuron, the learning gain degree Lg, corresponding to the modulation gain ratio, increases with increasing the learning cycle, and it saturates at about the 300th cycle. By varying pc from pc∗, we find that a plot of saturated learning gain degree Lg∗ versus pc forms a bell-shaped curve with a peak at pc∗ (where the diversity degree in spiking patterns of GR cells is also maximum). Consequently, the more diverse in recoding of GR cells, the more effective in motor learning for the OKR adaptation.
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Cerebelo/citología , Cerebelo/fisiología , Red Nerviosa/fisiología , Plasticidad Neuronal/fisiología , Nistagmo Optoquinético/fisiología , Adaptación Fisiológica/fisiología , Animales , Depresión Sináptica a Largo Plazo/fisiología , Células de Purkinje/fisiología , Sinapsis/fisiologíaRESUMEN
OBJECTIVE: Dyslexia is the most common learning disorder that affects 5-10% of school aged children. Eye movement abnormalities and visual processing deficits have been reported in some of dyslexic children. Objective of this study is to compare the eye-movement patterns of Iranian dyslexic children with those of non-dyslexic children as they perform the oculomotor tests and to explore the relationship between their eye-movement patterns and their reading ability. METHODS: Binocular eye movements were recorded by oculomotor subtype of videonystagmography (VNG) testing on 30 dyslexic children and 20 non-dyslexic age-matched children (aged 8-12) in both genders. Dyslexic children were diagnosed with DSM-V scale by experts in reading disorder centers. Gain of the pursuit and optokinetic tests and the latency, accuracy and velocity of the saccade test were measured in both groups of dyslexic and non-dyslexic children. The independent samples t-test, Chi-square test and linear regression test in SPSS v. 21 were used to analyze behavioral and eye-movement parameters. RESULTS: Compared to the non-dyslexic group, dyslexic children presented lower gain in pursuit and optokinetic tests, and increased latency with decreased accuracy in saccade test. All behavioral and eye-movement parameters without saccade velocity differed significantly among two groups. CONCLUSION: The atypical eye movement patterns observed in dyslexic children suggests a deficiency in the visual information processing and an immaturity of brain structures responsible for oculomotor skills.
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Dislexia/fisiopatología , Movimientos Oculares/fisiología , Estudios de Casos y Controles , Niño , Medidas del Movimiento Ocular , Femenino , Humanos , Irán , Masculino , Nistagmo Optoquinético/fisiología , Movimientos Sacádicos/fisiologíaRESUMEN
The vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) work synergistically to stabilize gaze in response to head movements. We previously demonstrated that a 14-day visuo-vestibular mismatch (VVM) protocol applied in freely behaving mice decreased the VOR gain. Here, we show for the first time that the OKR gain is also reduced and report on the recovery dynamics of both VOR and OKR after the end of the VVM protocol. Using sinusoidally-modulated stimulations, the decreases in VOR and OKR were found to be frequency-selective with larger reductions for frequencies < 0.5 Hz. Constant-velocity OKR stimulation tests demonstrated that the persistent components of the OKR were not modified while the transient, initial responses were. To identify the signals driving VOR and OKR reductions, we compared the responses of mice exposed to a high-contrast and no-contrast VVM. Despite being more robust in the high-contrast conditions, reductions were largely comparable and recovered with a similar time course. An analysis that directly compared VOR and OKR responses revealed that, alterations in the VOR were of significantly larger amplitude with significantly slower dynamics of recovery. Our findings are evidence for a frequency-selective influence of visual signals in the tuning of gaze stabilizing reflexes in normal mice.
Asunto(s)
Movimientos Oculares/fisiología , Percepción de Movimiento/fisiología , Nistagmo Optoquinético/fisiología , Fenómenos Fisiológicos Oculares , Reflejo Vestibuloocular/fisiología , Vestíbulo del Laberinto/fisiología , Animales , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
Purpose: Although zebrafish rods begin to develop as early as 2 days postfertilization (dpf), they are not deemed anatomically mature and functional until 15 to 21 dpf. A recent study detected a small electroretinogram (ERG) from rods in a cone mutant called no optokinetic response f (nof) at 5 dpf, suggesting that young rods are functional. Whether they can mediate behavioral responses in larvae is unknown. Methods: We first confirmed rod function by measuring nof ERGs under photopic and scotopic illumination at 6 dpf. We evaluated the role of rods in visual behaviors using two different assays: the visual-motor response (VMR) and optokinetic response (OKR). We measured responses from wild-type (WT) larvae and nof mutants under photopic and scotopic illuminations at 6 dpf. Results: Nof mutants lacked a photopic ERG. However, after prolonged dark adaptation, they displayed scotopic ERGs. Compared with WT larvae, the nof mutants displayed reduced VMRs. The VMR difference during light onset gradually diminished with decreased illumination and became nearly identical at lower light intensities. Additionally, light-adapted nof mutants did not display an OKR, whereas dark-adapted nof mutants displayed scotopic OKRs. Conclusions: Because the nof mutants lacked a photopic ERG but displayed scotopic ERGs after dark adaptation, the mutants clearly had functional rods. WT larvae and the nof mutants displayed comparable scotopic light-On VMRs and scotopic OKRs after dark adaptation, suggesting that these responses were driven primarily by rods. Together, these observations indicate that rods contribute to zebrafish visual behaviors as early as 6 dpf.
Asunto(s)
Células Fotorreceptoras Retinianas Bastones/fisiología , Visión Ocular/fisiología , Pez Cebra/fisiología , Animales , Visión de Colores/fisiología , Electrorretinografía , Técnicas de Genotipaje , Larva , Visión Nocturna/fisiología , Nistagmo Optoquinético/fisiologíaRESUMEN
Purpose: The immune-privileged environment and complex organization of retinal tissue support the retina's essential role in visual function, yet confound inquiries into cell-specific inflammatory effects that lead to dysfunction and degeneration. Caveolin-1 (Cav1) is an integral membrane protein expressed in several retinal cell types and is implicated in immune regulation. However, whether Cav1 promotes or inhibits inflammatory processes in the retina (as well as in other tissues) remains unclear. Previously, we showed that global-Cav1 depletion resulted in reduced retinal inflammatory cytokine production but paradoxically elevated retinal immune cell infiltration. We hypothesized that these disparate responses are the result of differential cell-specific Cav1 functions in the retina. Methods: We used Cre/lox technology to deplete Cav1 specifically in the neural retinal (NR) compartment to clarify the role NR-specific Cav1 (NR-Cav1) in the retinal immune response to intravitreal inflammatory challenge induced by activation of Toll-like receptor-4 (TLR4). We used multiplex protein suspension array and flow cytometry to evaluate innate immune activation. Additionally, we used bioinformatics assessment of differentially expressed membrane-associated proteins to infer relationships between NR-Cav1 and immune response pathways. Results: NR-Cav1 depletion, which primarily affects Müller glia Cav1 expression, significantly altered immune response pathway regulators, decreased retinal inflammatory cytokine production, and reduced retinal immune cell infiltration in response to LPS-stimulated inflammatory induction. Conclusions: Cav1 expression in the NR compartment promotes the innate TLR4-mediated retinal tissue immune response. Additionally, we have identified novel potential immune modulators differentially expressed with NR-Cav1 depletion. This study further clarifies the role of NR-Cav1 in retinal inflammation.
Asunto(s)
Caveolina 1/fisiología , Inflamación/inducido químicamente , Lipopolisacáridos/toxicidad , Retina/metabolismo , Retinitis/inducido químicamente , Animales , Western Blotting , Caveolina 1/deficiencia , Citocinas/metabolismo , Sinergismo Farmacológico , Electrorretinografía , Citometría de Flujo , Inmunohistoquímica , Inflamación/metabolismo , Inflamación/patología , Inyecciones Intravítreas , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Microscopía Confocal , Nistagmo Optoquinético/fisiología , Proteómica , Retinitis/metabolismo , Retinitis/patología , Salmonella typhimurium , Receptor Toll-Like 4/metabolismoRESUMEN
Vertical vergence is generally associated with one of three mechanisms: vestibular activation during a head tilt, induced by vertical visual disparity, or as a by-product of ocular torsion. However, vertical vergence can also be induced by seemingly unrelated visual conditions, such as optokinetic rotations. This study aims to investigate the effect of vision on this latter form of vertical vergence. Eight subjects (4m/4f) viewed a visual scene in head erect position in two different viewing conditions (monocular and binocular). The scene, containing white lines angled at 45° against a black background, was projected at an eye-screen distance of 2 m, and rotated 28° at an acceleration of 56°/s2. Eye movements were recorded using a Chronos Eye-Tracker, and eye occlusions were carried out by placing an infrared-translucent cover in front of the left eye during monocular viewing. Results revealed vergence amplitudes during binocular viewing to be significantly lower than those seen for monocular conditions (p = 0.003), while torsion remained unaffected. This indicates that vertical vergence to optokinetic stimulation, though visually induced, is visually suppressed during binocular viewing. Considering that vertical vergence is generally viewed as a vestibular signal, the findings may reflect a visually induced activation of a vestibular pathway.