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Kang Y. H., Kim B. C., Park K. R., Yon J. Y., Kim H. J., Tak H. J., Piao Z., Kim M. K., Lee S. H. Visual pathway-related horizontal reference plane for three-dimensional craniofacial analysis Orthod Craniofac Res 2012; 15:245-254. © 2012 John Wiley & Sons A/S Structured Abstract Authors - Kang YH, Kim BC, Park KR, Yon JY, Kim HJ, Tak HJ, Piao Z, Kim MK, Lee SH Objectives - To construct three-dimensional (3D) horizontal reference planes based on visual pathway and to determine their stability and reliability by analyzing the structural patterns of normal and dysmorphology for 3D craniofacial analysis. Setting and Sample Population - Thirty-six subjects with maxillofacial dysmorphology and malocclusion, and eight normal controls. Materials and Methods Population - On the 3D computed tomographic images of the subjects, the visual pathway-based planes, including the orbital axis plane (OAP), visual axis plane (VAP), and the optical axis plane (OpAP), were constructed and evaluated. Results - The OAP, but not the VAP and OpAP, showed the ideal relationship between the midsagittal and posterior maxillary plane, and properly described the different patterns of maxillofacial dysmorphology with craniofacial plane 1 of Delaire's analysis and the occlusal plane. Conclusions - The proposed visual pathway-related horizontal reference planes, and in particular the OAP, seem to correctly express the visual axis and the position of the head in natural head position and can be used as a horizontal reference plane for the 3D analysis of craniofacial dysmorphology and anthropology. [ABSTRACT FROM AUTHOR]

Abstract: An electrophysiological study on the effect of aging on the visual pathway and various levels of visual information processing (primary cortex, associate visual motion processing cortex and cognitive cortical areas) was performed. We examined visual evoked potentials (VEPs) to pattern-reversal, motion-onset (translation and radial motion) and visual stimuli with a cognitive task (cognitive VEPs – P300 wave) at luminance of 17cd/m2. The most significant age-related change in a group of 150 healthy volunteers (15–85years of age) was the increase in the P300 wave latency (2ms per 1year of age). Delays of the motion-onset VEPs (0.47ms/year in translation and 0.46ms/year in radial motion) and the pattern-reversal VEPs (0.26ms/year) and the reductions of their amplitudes with increasing subject age (primarily in P300) were also found to be significant. The amplitude of the motion-onset VEPs to radial motion remained the most constant parameter with increasing age. Age-related changes were stronger in males. Our results indicate that cognitive VEPs, despite larger variability of their parameters, could be a useful criterion for an objective evaluation of the aging processes within the CNS. Possible differences in aging between the motion-processing system and the form-processing system within the visual pathway might be indicated by the more pronounced delay in the motion-onset VEPs and by their preserved size for radial motion (a biologically significant variant of motion) compared to the changes in pattern-reversal VEPs. [Copyright &y& Elsevier]

Abstract: Purpose: Altered metabolic activity has been identified as a potential contributing factor to the neurodegeneration associated with primary open angle glaucoma (POAG). Consequently, we sought to determine whether there is a relationship between the loss of visual function in human glaucoma and resting blood perfusion within primary visual cortex (V1). Methods: Arterial spin labeling (ASL) functional magnetic resonance imaging (fMRI) was conducted in 10 participants with POAG. Resting cerebral blood flow (CBF) was measured from dorsal and ventral V1. Behavioral measurements of visual function were obtained using standard automated perimetry (SAP), short-wavelength automated perimetry (SWAP), and frequency-doubling technology perimetry (FDT). Measurements of CBF were compared to differences in visual function for the superior and inferior hemifield. Results: Differences in CBF between ventral and dorsal V1 were correlated with differences in visual function for the superior versus inferior visual field. A statistical bootstrapping analysis indicated that the observed correlations between fMRI responses and measurements of visual function for SAP (r =0.49), SWAP (r =0.63), and FDT (r =0.43) were statistically significant (all p <0.05). Conclusions: Resting blood perfusion in human V1 is correlated with the loss of visual function in POAG. Altered CBF may be a contributing factor to glaucomatous optic neuropathy, or it may be an indication of post-retinal glaucomatous neurodegeneration caused by damage to the retinal ganglion cells. [Copyright &y& Elsevier]

Abstract: Mounting evidence implicates axonal transport defects, typified by the presence of axonal varicosities with aberrant accumulations of cargo, as an early event in Alzheimer''s disease (AD) pathogenesis. Work identifying amyloid precursor protein (APP) as a vesicular motor receptor for anterograde axonal transport further implicates axonal transport in AD. Manganese-enhanced MRI (MEMRI) detects axonal transport dynamics in preclinical studies. Here we pursue an understanding of the role of APP in axonal transport in the central nervous system by applying MEMRI to hippocampal circuitry and to the visual pathway in living mice homozygous for either wild type or a deletion in the APP gene (n=12 for each genotype). Following intra-ocular or stereotaxic hippocampal injection, we performed time-lapse MRI to detect Mn2+ transport. Three dimensional whole brain datasets were compared on a voxel-wise basis using within-group pair-wise analysis. Quantification of transport to structures connected to injection sites via axonal fiber tracts was also performed. Histology confirmed consistent placement of hippocampal injections and no observable difference in glial-response to the injections. APP−/− mice had significantly reduced transport from the hippocampus to the septal nuclei and amygdala after 7h and reduced transport to the contralateral hippocampus after 25h; axonal transport deficits in the APP−/− animals were also identified in the visual pathway. These data support a system-wide role for APP in axonal transport within the central nervous system and demonstrate the power of MEMRI for assessing neuronal circuitry involved in memory and learning. [Copyright &y& Elsevier]

It is a well-known fact that the perceived brightness of any surface depends on the brightness of the surfaces that surround it. This phenomenon is termed as brightness induction. Isotropic arrays of multi-scale DoG (Difference of Gaussians) as well as cortical Oriented DoG (ODOG) and extensions thereof, like the Frequency-specific Locally Normalized ODOG (FLODOG) functions have been employed towards prediction of the direction of brightness induction in many brightness perception effects. But the neural basis of such spatial filters is seldom obvious. For instance, the visual information from retinal ganglion cells to such spatial filters, which have been generally speculated to appear at the early stage of cortical processing, are fed by at least three parallel channels viz. Parvocellular (P), Magnocellular (M) and Koniocellular (K) in the subcortical pathway, but the role of such pathways in brightness induction is generally not implicit. In this work, three different spatial filters based on an extended classical receptive field (ECRF) model of retinal ganglion cells, have been approximately related to the spatial contrast sensitivity functions of these three parallel channels. Based on our analysis involving different brightness perception effects, we propose that the M channel, with maximum conduction velocity, may have a special role for an initial sensorial perception. As a result, brightness assimilation may be the consequence of vision at a glance through the M pathway; contrast effect may be the consequence of a subsequent vision with scrutiny through the P channel; and the K pathway response may represent an intermediate situation resulting in ambiguity in brightness perception. The present work attempts to correlate this phenomenon of pathway selection with the complementary nature of these channels in terms of spatial frequency as well as contrast. [ABSTRACT FROM AUTHOR]

We assessed the effect of physical effort with increasing intensity on neural activity in the visual pathway in volleyball players (n = 10) and non-athletes (n = 10). Participants performed three 10-min tests of increasing intensity on a cycle ergometer. Each participant was assigned individual workloads below the lactate threshold (40% [Vdot]O2max), at the lactate threshold (65–75% [Vdot]O2max), and above the lactate threshold (80% [Vdot]O2max). Four recordings of visual evoked potentials were made: pre-exercise and immediately after each of the three subsequent tests. We assessed neural activity of the visual pathway by examining the amplitude and latency of the N75, P100, and N135 components of the visual evoked potentials waveform. Pre-exercise P100 wave latency was shorter (P < 0.05) in volleyball players than in non-athletes. In non-athletes, the latency of P100 following the first and second effort (40% and 65–75% [Vdot]O2max) was reduced compared with pre-exercise (P < 0.01). However, P100 latency increased and P100 amplitude decreased after the third test (80% [Vdot]O2max) in non-athletes. In contrast, no significant changes in the latency or amplitude of visual evoked potentials were observed in the athletes in the three tests. Neural conductivity in the visual pathway after exercise might be at least partially dependent on the individual's personal training adaptation status. [ABSTRACT FROM AUTHOR]

Purpose: To estimate prospectively late ocular manifestations in patients after aneurysmal subarachnoid hemorrhage (SAH) treated with aneurysm clipping. Methods: Forty-six patients (12 men and 34 women), 23-69 years of age, were included in this study. A conventional ophthalmological examination, visual evoked potentials (VEPs), and static perimetry were performed on all patients. The mean interval between the onset of SAH and the aforementioned examination was 1.9 ± 1.3 years (range 0.5-5 years). The following were compared between patients with affected and non-affected visual fields as well as between those with normal and abnormal VEPs: sex, age, time from SAH to surgery, Hunt and Hess scale, Glasgow Coma Scale, Glasgow Outcome Scale, grading of SAH according to the Fisher scale, and the size and site of aneurysm. Results: Visual field defects were found in 23 patients (50%). In all of these patients, both eyes were affected. The most frequent type of visual field defects were: constricted field (47.8%), multiple peripheral foci (26.1%), and superior field defect (17.4%). There was no significant relationship between the analyzed factors and the occurrence of visual field defects, although statistical significance was almost observed in respect to the Fisher scale ( p = 0.055). Deterioration in VEPs was observed in nine patients (19.6%). In the group of patients with abnormal VEPs, the time from onset of SAH to surgery was 2.6 ± 1.8 days, whereas in the group of patients with normal VEPs this time amounted to 6.4 ± 2.4 days ( p = 0.02). In patients with no changes in VEPs, the mean Fisher score was significantly higher than in the group with abnormal VEPs (2.8 ± 0.6 vs 2.0 ± 0.4 respectively, p = 0.04). Conclusion: Visual field defects and VEP deterioration are frequent late ocular manifestations of SAH treated with aneurysm clipping. Damage to the visual pathway correlates with the severity of SAH and timing of aneurysmal surgery. [ABSTRACT FROM AUTHOR]

Infantile nystagmus syndrome (INS; formerly called congenital nystagmus) is an ocular motor disorder characterized by several typical nystagmus waveforms. To date, restrictions inherent to human research and the absence of a handy animal model have impeded efforts to identify the underlying mechanism of INS. Displaying INS-like spontaneous eye oscillations, achiasmatic zebrafish belladonna ( bel) mutants may provide new insights into the mystery of INS. In this study, we demonstrate that these spontaneous eye oscillations match the diagnostic waveforms of INS. As a result, zebrafish bel mutants can be used as an animal model for the study of INS. In zebrafish bel mutants, visual pathway abnormalities may contribute to the spontaneous nystagmus via an inverted signal to the pretectal area. We hypothesized that human INS may also be linked to visual pathway abnormalities (possibly underdiagnosed in INS patients) in a similar way. [ABSTRACT FROM AUTHOR]

Abstract: Visual information is sent from the retina to central visual targets through the optic nerve formed of retinal ganglion cells’ (RGCs) axons. In rodents, the superior colliculus (SC) is the major site of termination of retinal axons, whilst in primates and felines, it is the lateral geniculate nucleus (LGN). Glaucoma is a progressive optic neuropathy characterized by RGC death. There is increasing evidence that neuronal changes occur both in retina and central visual targets in glaucoma and other neurodegenerative diseases such as Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS). Dendrites are fine neuronal processes which support postsynaptic contact elements and are responsible for receiving synaptic signals. The morphology of dendrites has a profound impact on integrating neuronal input to the central nervous system from peripheral targets. This review summarizes different dendritic changes that have been recorded in neurodegenerative processes including those occurring in development, ageing and diseases. The findings suggest dendritic pathology is an early sign in disease and underline the importance of synapto-dendritic structure, providing new insights into therapeutic strategies. [Copyright &y& Elsevier]

Motion detection is typically spared in blindsight, which results from damage to the striate cortex (area V1)of the brain that is sufficient to eliminate conscious visual awareness and severely reduce sensitivity to luminance contrast, especially for high spatial and low temporal frequencies. Here we show that the discrimina- tion of motion direction within cortically blind fields is not attributable to feature tracking (the detection of changes in position or shape), but is due instead to the detection of first- order motion energy (spatiotemporal changes in luminance). The key to this finding was a version of the line motion illusion entailing reverse-phi motion in which opposing motion directions are simultaneously cued by motion energy and changes in stimulus shape. In forced choice tests, a blindsighted test subject selected the direction cued by shape change when the stimulus was presented in his intact field, but reliably selected the direction cued by motion energy when the same stimulus was presented in his blind field, where relevant position information was either inaccessible or invalid. Motion energy has been characterized as objectless, so reliance on motion energy detection is consistent with impaired access to shape information in blindsight. The dissociation of motion direction by visual field (cortically blind vs. intact) provides evidence that two pathways from the retina to MT/V5 (the cortical area specialized for motion perception) are functionally distinct: the retinogeniculate pathway through V1 is specialized for feature-based motion perception, whereas the retinocollicular pathway, which bypasses V1, is specialized for detecting motion energy. [ABSTRACT FROM AUTHOR]

The anterior visual pathway (AVP) can be at risk during gamma knife surgery (GKS). There is no standardised published methodology for protecting the AVP. This paper suggests such an approach in relation to the treatment of meningiomas. There were 67 patients with a mean age of 48.8 years and a minimum follow-up of 25 months. A recent perimetry was available on the day of treatment. The visual pathway was outlined and the maximum radiation dose was recorded. In some cases a dose volume histogram (DVH) of the AVP was constructed to assess the volume receiving more than the desired maximum dose. The aim was a maximum dose between 8 and 10 Gy. A principle of sub-optimal dose planning was used to protect vision. Follow-up included new visual field examinations. Various anatomical locations place different parts of the AVP at risk. No patient suffered a deterioration of vision. In 21 (38.7%) patients there was an improvement in the visual field and in 7 (44%) associated diplopia improved. Vision could improve without corresponding tumour shrinkage. A standard measure of radiation toleration of the AVP could be the maximum dose within its volume, probably at least 10 Gy. Computerised perimetry should be available on the day of treatment and at follow-up. There is no need to have a distance between the tumour margin and the visual pathway. Sub-optimal dose-planning has been advantageous. Improvement in vision is not necessarily a consequence of tumour shrinkage. [ABSTRACT FROM AUTHOR]

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Abstract: The vagus nerve participates in the control and regulation of important autonomous functions, emotional tasks, and neural activity. Electrical vagus nerve stimulation (VNS) is an approved procedure for the treatment of refractory epilepsy in humans. VNS has also been shown to improve mood complaints and cognitive function in both human patients and animals. Thus, the purpose of this study was to analyse and describe the effects of VNS on the development and establishment of sensory habituation and electrographic activity of the visual pathway in freely moving cats. Six cats had implants placed in the optic chiasm (OC), lateral geniculate body (LGB), mesencephalic reticular formation (MRF), primary visual cortex (VC) of the left hemisphere, and left vagus nerve. Immediately after surgery, all cats presented anisocoria and relaxation of the left nictitant membrane. Also showed vegetative-type responses such as myosis, licking, and swallowing during VNS. Animals were then subjected to repeated luminous stimuli at intervals of 1 and 3s to cause habituation. The effect of VNS on the frequency and latency of the habituation episodes and the electrographic changes in the registered brain structures were analysed. Latency analysis showed that VNS delayed the first habituation episode. VNS had transitory effects on the neural activity of the primary visual pathway structures, which caused a small but measurable delay in the establishment of habituation. In conclusion, VNS interferes with the development and establishment of visual habituation, an elementary form of non-associative learning, in freely moving cats. [Copyright &y& Elsevier]

Hwa-Byung (HB) is a Korean culture-bound psychiatric syndrome caused by the suppression of anger. HB patients have various psychological and somatic symptoms, such as chest discomfort, a sensation of heat, and the sensation of having an epigastric mass. In this study, we measured brain activity in HB patients and healthy individuals in response to affective facial stimuli. Using functional magnetic resonance imaging (fMRI), the current study measured neural responses to neutral, sad, and angry facial stimuli in 12 healthy individuals and 12 patients with HB. In response to all types of facial stimuli, HB patients showed increased activations in the lingual gyrus and fusiform gyrus compared with healthy persons, but they showed relatively lower activation in the thalamus. We also found that patients with HB showed lower activity in response to the neutral condition in the right ACC than healthy controls. The current study indicates that the suppression of affect results in aberrant function of the brain regions of the visual pathway, and functional impairment in the ACC may contribute to the pathophysiology of HB. [ABSTRACT FROM AUTHOR]

Abstract: Linear and nonlinear systems analysis are tools that can be used to study communication systems like the visual system. The first step of systems analysis often is to test whether or not the system is linear. Retinal pathways are surprisingly linear, and some neurons in the visual cortex also emulate linear sensory transducers. We conclude that the retinal linearity depends on specialized ribbon synapses while cortical linearity is the result of balanced excitatory and inhibitory synaptic interactions. [Copyright &y& Elsevier]

A literature review was performed by content experts in neuro-ophthalmology and neuroradiology using a systematic English-language Medline search (1994–2008) limited to articles with relevance to neuro-ophthalmic and orbital imaging. The information covered in this review includes: (i) the basic mechanics, indications and contraindications for cranial and orbital computed tomography and magnetic resonance (MR) imaging; (ii) the utility and indications for intravenous contrast, (iii) the use of specific MR sequences; (iv) the techniques and ophthalmic indications for computed tomography/MR angiography and venography; and (v) the techniques and indications for functional MR imaging, positron emission tomography scanning and single photon emission computed tomography. Throughout the review accurate and timely communication with the neuroradiologist regarding the clinical findings and suspected location of lesions is emphasized so as to optimize the ordering and interpretation of imaging studies for the ophthalmologist. [ABSTRACT FROM AUTHOR]

The purpose of this study, on mice, was to determine whether memantine, a glutamate-receptor antagonist of the N-methyl-d-aspartate (NMDA) subtype, protects against neuronal degeneration in the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) after the induction of retinal damage by intravitreal injection of NMDA. NMDA (20 mM/2 μl) was injected into the vitreous body of the left eye in mice (day 0). To evaluate the neuroprotective effect of memantine, mice were assigned to one of two memantine-treated groups: receiving a daily administration of memantine at 30 mg/kg/day, p.o. either from day 0 (administered at 1 h before NMDA injection) to day 90 (pretreated group) or from day 7 to day 90 (post-treated group). The pretreated group exhibited significant suppression of the retinal damage induced by intravitreal injection of NMDA and significant prevention of transsynaptic neuronal degeneration in the dLGN and SC on the contralateral side. Although the mice of the post-treated group displayed no reversion of such retinal damage, they did exhibit protection against neuronal degeneration in the LGN and SC on the contralateral side. These data indicate that memantine can protect against transsynaptic neuronal degeneration in the murine brain (LGN and SC) even if treatment is begun after retinal ganglion cell (RGC) death has started. Memantine protects against the secondary neuronal degeneration in brain regions in the visual pathway that occurs after retinal damage in mice. [ABSTRACT FROM AUTHOR]

Signal detection psychophysical experiments were conducted to investigate the visual path of children with autism. Computer generated images with Gaussian noise were used. Simple signals, still and in motion were embedded in the background noise. The computer monitor was linearized to properly display the contrast changes. To our knowledge, this is the first time that experiments of this type have been done with observers with autism. Our results show that the visual capabilities of typically developed children were superior to those of the children with autism, and that the related problems of children with autism are sensation related only in a reduced proportion. There is no evidence that they are disabled in detecting simple visual stimuli, still and in motion. [ABSTRACT FROM AUTHOR]

Abstract: Chondroitin sulfate proteoglycans elicit a selective inhibition to neurite growth from ventrotemporal (VT) but not dorsonasal (DN) retina, potentiating the bilateral routing of axons in the mouse optic chiasm. We examined whether this selective response is mediated by a difference in protein kinase C (PKC) expression. Effects of suppressing PKC activity in explant preparations of embryonic day 14 retinae with inhibitor Gö6976 or Ro-32-0432 abolished the chondroitin sulfate inhibition to the VT neurites but had no effect to the DN neurites. Whether these responses rely on a difference in expression of PKC in the growth cones was examined using antibodies against six isozymes of PKC. Among these the α, βI and ɛ isozymes were expressed prominently in the retinal growth cones; whilst the βII, δ and γ isozymes were barely detected. Moreover, while the α and ɛ isozymes were abundant in the filopodial and lamellipodial processes, the βI isozyme was restricted largely in the core region of the growth cones. Despite these subtype specific localization, there was no significant difference in expression of any of these PKC isozymes between growth cones from VT and DN retina, indicating that the selective response to chondroitin sulfates is not likely generated by a regulation of PKC expression, but by expression of surface molecules that interact with chondroitin sulfate proteoglycans. [Copyright &y& Elsevier]

Abstract: The vertebrate nervous system has been shown to contain high concentrations of intracellular calcium-binding proteins, each of them with a restricted expression pattern in specific brain regions and specific neuronal subpopulations. Using immunohistochemical staining techniques, we analyzed the expression pattern of calbindin, calretinin and parvalbumin in visual brain areas of a songbird species, the zebra finch (Taeniopyga guttata). Here we show that the analyzed proteins are expressed in a complementary fashion within different brain substructures generally corresponding to functional subpathways of the avian visual system. In detail, calbindin is expressed in the brain structures that belong to the thalamofugal pathway, whereas parvalbumin-positive neurons are found in the brain structures that are part of the tectofugal visual pathway. Originally, the expression of calcium-binding proteins has been associated with specific morphological or neurochemical criteria of neurons. Our results suggest that their expression pattern also indicates a functional segregation of brain substructures linked to vision in the zebra finch brain. As the selective labeling of functional streams has also been shown for the visual system in mammalian species, function-selective expression of calcium-binding proteins might be a general feature of vertebrates. [Copyright &y& Elsevier]

Abstract: In this study, axial (λ ||) and radial (λ ⊥) diffusivities derived from diffusion tensor imaging (DTI) were used to evaluate white matter injury in brains of mice affected by experimental autoimmune encephalomyelitis (EAE). Sixteen female C57BL/6 mice were immunized with amino acids 35–55 of myelin oligodendrocyte glycoprotein (MOG35–55). Three months after immunization, optic nerve and tract were severely affected with 19% and 18% decrease in λ || respectively, suggesting the presence of axonal injury. In addition, a 156% and 86% increase in λ ⊥ was observed in optic nerve and tract respectively, suggestive of myelin injury. After in vivo DTI, mice were perfusion fixed and immunohistochemistry for the identification of myelin basic protein (MBP) and phosphorylated neurofilament (pNF) was performed to verify the presence of axonal and myelin injury. The present study demonstrated that the visual pathway is selectively affected in MOG35–55 induced murine EAE and these injuries are non-invasively detectable using λ || and λ ⊥. [Copyright &y& Elsevier]

Purpose: Growing axons express a number of proteins associated with axonal growth which are thought to be critical for regeneration and sprouting. Whether these proteins are expressed during injury-induced axonal remodeling is tested in this paper. Methods: The posterior half of the adult goldfish tectum was removed leaving the anterior half intact. This causes optic fibers from nasal retina, which project to posterior tectum, to displace temporal fibers from the anterior remnant and form a compressed retinotopic projection of the entire retina onto the anterior tectum. Immunohistochemistry using an antibody shown here to recognize growing and regenerating fibers in goldfish was used to monitor optic fibers. Results: As expected, surgery induced reactivity in the axotomized nasal axons peaking at 1 month which returned to normal at 2 months when compression was completed. Unexpectedly, axons from temporal retina showed no detectable reactivity even though they were induced to grow anteriorly by the invading nasal fibers. Conclusions: Extensive axonal remodeling and synaptic rearrangement can occur without reentering the growth state associated with axonal growth and regeneration. [ABSTRACT FROM AUTHOR]

The purpose of the study was to examine the brain and the visual pathway of patients with non-arteritic anterior ischaemic optic neuropathy (NAION) by using conventional MRI (cMRI) and volumetric magnetisation transfer imaging (MTI). Thirty NAION patients, aged 67.5 +/- 8.14 years, and 28 age- and gender-matched controls were studied. MTI was used to measure the magnetisation transfer ratio (MTR) of the chiasm and for MTR histograms of the brain. The presence of areas of white matter hyperintensity (WMH) was evaluated on fluid-attenuated inversion recovery (FLAIR) images. Area of the optic nerves (ONs) and volume of the chiasm were assessed, as were coronal short-tau inversion recovery (STIR) and MTI images, respectively. More areas of WMH were observed in patients (total 419; mean 14.4; SD 19) than in controls (total 127; mean 4.7; SD 5.7), P < 0.001. Area (in square millimetres) of the affected ONs, volume(in cubic millimetres) and MTR (in percent) of the chiasm (10.7 +/- 4.6), (75.8 +/- 20.2), (56.4 +/- 6.5), respectively, were lower in patients than in controls (13.6 +/- 4.3), (158.2 +/- 75.3) (62.1 +/- 6.2), respectively, P < 0.05. Mean MTR of brain histograms was lower in patients (53.0 +/- 8.0) than in controls (58.0 +/- 5.6), P < 0.05. NAION is characterised by decreased ON and chiasmatic size. The low MTR of the chiasm and brain associated with increased areas of WMH may be suggestive of demyelination and axonal damage due to generalised cerebral vascular disease. [ABSTRACT FROM AUTHOR]

The data presented in this article was collected after reviewing clinical findings gathered from using various anxiety control methods on apprehensive patients. We examined clinical applications of the eye movement (EM) component of Eye Movement Desensitization (EMD) on fearful dental patients who have histories of traumatic dental experiences. We also used Bi-Digital O-Ring Test (BDORT) to select the proper dosage of sedative to minimize the adverse side effects. For patients who did not respond well to EM, we used BDORT to select the proper sedative medication and its dosage. In certain difficult cases, we supplemented these techniques with acupuncture to augment the sedative effects. Findings were based on the clinical impressions and assessments of both the patients and the operating team. Results showed that EM, although effective in enabling patients to undergo non-invasive dental procedures such as clinical examination and simple prophylaxis, had only limited beneficial effect with invasive procedures such as extraction, drilling, and injections, etc. We also found that BDORT greatly reduced adverse side effects of sedatives such as hypertension, hypotension, hypoxia, tachycardia, bradycardia, nausea, and vomiting. For most apprehensive patients, we found that EMD and acupuncture combined with BDORT predetermined dosage for the submucosal sedation enabled these patients to undergo the complete dental treatment. The authors try to explain the mechanism of BDORT and EM in terms of visual awareness (or consciousness) and preferred patterns, where neurons in the brain respond to the actions and/or direction of movement. The authors believe that BDORT and EM could have better results if the persons performing BDORT have visual awareness and are focused on the task; whereas in EM, the patient's eye on the therapist's hand movements. A more focused approach via visual pathway will result in more favorable results in EM. Likewise, performing BDORT absentmindedly could lead to false results if visual awareness (or consciousness) is absent. "Preferred pattern" will arouse neurons in the brain to cause conscientiousness, and performing BDORT with 'open eyes' arouse the necessary visual awareness that is necessary for the successful performance of BDORT tasks. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the nonlinear characteristics of visual evoked potentials (VEPs), and their correlation with the visual responses on parvocellular and magnocellular pathways. First and second-order kernels of the VEPs elicited by several checkerboard patterns were estimated, and their relations to the visual pathway responses were investigated.Methods: VEPs elicited by checkerboard pattern (0.5, 1.0, 2.0 and 4.0 c/d) alternating based on pseudorandom binary sequence were measured, and their binary kernels were calculated. First and second-order binary kernels were compared with amplitudes of the steady-state VEPs (S-VEPs) to pattern reversal stimulation with a constant temporal frequency (4, 8, 12, 16, and 32 Hz).Results: Positive peak latencies at 150 ms (P150) of second-order first and second slices were correlated with S-VEP amplitude for higher temporal frequencies, indicating that the first and second slices reflect the response of the magnocellular. However, for second and third slices, their amplitudes were partially correlated with 4-16 Hz S-VEP, and this indicated that the second slice contains both magno- and parvocellular pathway responses. P150 latencies of third slices were correlated with S-VEP for lower temporal frequencies, indicating that third slice reflects the response of the parvocellular pathway.Conclusions: The lower slices of second-order binary kernels reflect the response of the magnocellular pathway and the higher slices reflect those on the parvocellular pathway in the human visual system of VEPs. [ABSTRACT FROM AUTHOR]

Abstract: The lateral forebrain of zebra finches that comprises parts of the lateral nidopallium and parts of the lateral mesopallium is supposed to be involved in the storage and processing of visual information acquired by an early learning process called sexual imprinting. This information is later used to select an appropriate sexual partner for courtship behavior. Being involved in such a complicated behavioral task, the lateral nidopallium should be an integrative area receiving input from many other regions of the brain. Our experiments indeed show that the lateral nidopallium receives input from a variety of telencephalic regions including the primary and secondary areas of both visual pathways, the globus pallidus, the caudolateral nidopallium functionally comparable to the prefrontal cortex, the caudomedial nidopallium involved in song perception and storage of song-related memories, and some parts of the arcopallium. There are also a number of thalamic, mesencephalic, and brainstem efferents including the catecholaminergic locus coeruleus and the unspecific activating reticular formation. The spatial distribution of afferents suggests a compartmentalization of the lateral nidopallium into several subdivisions. Based on its connections, the lateral nidopallium should be considered as an area of higher order processing of visual information coming from the tectofugal and the thalamofugal visual pathways. Other sensory modalities and also motivational factors from a variety of brain areas are also integrated here. These findings support the idea of an involvement of the lateral nidopallium in imprinting and the control of courtship behavior. [Copyright &y& Elsevier]

We have determined whether chondroitin sulphate (CS) glycosaminoglycans are sufficient to direct a selective inhibition of neurite growth from ventral temporal (VT) but not from dorsal nasal (DN) retina in mouse embryos; this may underlie the formation of axon divergence in the optic chiasm. Explants from the retinal region of embryonic day-14 mouse were grown on a laminin–polylysine substrate near to a circular spot coated with CS. In control cultures, in which no CS was added to the spot, both VT and DN retinal neurites grew extensively into the coated territory. When presented with spots coated with 10 mg/ml CS, neurite growth from the VT retina into the CS territory was dramatically reduced but that from the DN retina was not significantly affected. The selective inhibition to VT neurites was completely abolished by treatment with chondroitinase ABC, indicating a specific contribution of CS glycosaminoglycan in this regionally specific behaviour. This differential behaviour was not observed in explants presented with a lower or higher concentration of CS or in explants grown on substrate coated with a different laminin concentration. Thus, a critical ratio of CS to laminin seems to be essential to induce this differential behaviour in retinal neurites towards contact with CS. Furthermore, this behavior was not observed in explants cultured directly on a CS-rich substrate, suggesting that contact with growth-promoting molecules is necessary for the selective responses of retinal neurites during subsequent contact with CS. We concluded that CS glycosaminoglycan is sufficient to drive selective inhibition of VT but not DN neurites and that, together with a critical combination of growth-promoting factors, it may control the axon divergence process at the mouse optic chiasm. [ABSTRACT FROM AUTHOR]

Abstract: By injecting a single 60μg dose of corticosterone into the eggs of domestic chicks on day 18 of incubation, we have shown that elevated levels of this hormone affect the development of asymmetry in the visual projections from the thalamus to the Wulst regions in the left and right hemispheres of the forebrain. In vehicle-treated (control) embryos this visual pathway develops asymmetry in response to light stimulation during the final stages of incubation, when the embryo is oriented so that its left eye is occluded by its body and its right eye can be stimulated by light entering through the egg shell. Pre-hatching exposure to light leads to more projections from the left side of the thalamus to the right Wulst than from the right side of the thalamus to the left Wulst, as confirmed here by injection of the tracers Fluorogold and Rhodamine into the left and right Wulst followed by counting the number of labelled cell bodies in the thalamus (asymmetry greater in males than females). The chicks injected with corticosterone pre-hatching did not develop any group bias for asymmetry in response to light exposure before hatching. They were random with respect to presence/absence of lateralization and, when present, the lateralization was not as strong as in the controls and its direction was random. The corticosterone-treated group had fewer projections from the left side of the thalamus to the right Wulst than did the controls. The results are considered with respect to maternal deposits of the hormone in the yolk and pre-hatching stress of the embryo. [Copyright &y& Elsevier]

We have investigated whether the two major brain chondroitin sulfate (CS) proteoglycans (PGs), phosphacan and neurocan, are expressed in patterns that correlate to the axon order changes in the mouse retinofugal pathway. Expression of these proteoglycans was examined by polyclonal antibodies against phosphacan and N- and C-terminal fragments of neurocan. In E13–E15 mouse embryos, when most optic axons grow in the chiasm and the optic tract, phosphacan and neurocan were observed in the inner regions of the retina. In the chiasm and the tract, phosphacan but not neurocan was expressed prominently at the midline and in the deep parts of the tract. Both proteoglycans were observed on the chiasmatic neurons, which have been shown to regulate axon divergence at the chiasmatic midline and the chronotopic fiber ordering in the tract, but phosphacan appeared to be the predominant form that persists to later developmental stages. Intense staining of both proteoglycans was also observed in a strip of glial-like elements in lateral regions of the chiasm, partitioning axons in the stalk from those in the tract. We conclude that phosphacan but not neurocan is likely the major carrier of the CS glycosaminoglycans that play crucial functions in axon divergence and age-related axon ordering in the mouse optic pathway. Furthermore, localization of these carrier proteins in the optic pathway raises a possibility that these two proteoglycans regulate axon growth and patterning not only through the sulfated sugars but also by interactions of the protein parts with guidance molecules on the optic axons. [Copyright &y& Elsevier]

The nucleus rotundus (ROT) is a major relay station in the tectofugal pathway of the avian visual system. In this study, some quantitative features of ROT in developing chicks were analysed using new stereological methods. Total neuron number (N) and mean volume (V) of ROT were estimated by the optical fractionator method and by the Cavalieri principle, respectively. Neuronal density of neurons in ROT was calculated from these data. The eyes of the chick embryo are not normally stimulated by light until days E19/20. Therefore in this study, chicks at three developmental stages were investigated: on the 17th embryonic day (E17), that is before light stimulation of the visual system, at the time of hatch (0-day, stimulated by light) and 10 days after hatch (10-day). The results showed that N was reduced by 27% between E17 and 0-day, and 7.8% between 0- and 10-day while neuronal density was reduced by 15% and 32% over the same periods. It is concluded that the reduction of neuronal density during the pre-hatch period may be due to neuron loss, whereas the post-hatch decrease of neuronal density may be the result of an increase in ROT total volume. Cell loss was more prominent in the pre-hatch than in the post-hatch period. Estimates of neuronal density in the developing ROT are not useful indicators of developmental status, since they do not relate to total neuron number. [Copyright &y& Elsevier]

The distribution of AMPA-type glutamate receptor (GluR) subunits was studied in the Edinger–Westphal nucleus (EW) of chicks and pigeons. GluR1, GluR2, GluR3 and GluR4 subunits appeared to be present in EW neurons of both species, but interspecific differences were observed in the abundance of the different types of subunits found in EW neurons. Of particular note, GluR2 immunoreactivity was present in the vast majority (ca. 80%) of neurons of pigeon EW but was found in only a small fraction (ca. 15%) of chick EW neurons. Scarcity of the GluR2 subunit in chick EW was confirmed by in situ hybridization. Because of the tendency for parvalbumin to be localized to neurons that are selectively deficient in GluR2, we also studied the localization of parvalbumin, as well as other calcium-binding proteins, in EW of chick and pigeon. Parvalbumin was found in more than 50% of chick EW neurons but was not detected in pigeon EW neurons. Our results suggest that there are major glutamatergic inputs to EW neurons in both pigeons and chicks. Furthermore, there are likely to be more AMPA-type calcium-permeable glutamate receptors in EW neurons of chick than in pigeon, since it is known that the subtype containing the edited GluR2 subunit is not calcium permeable. [Copyright &y& Elsevier]

Visual pathways of a new mutant of chicken (GSN/1) with hereditary visual impairment were ophthalmologically, electrophysiologically, and histopathologically examined. Clinically, GSN/1 chickens drooped and had decreased locomotor activity. As an indicator of visual acuity, the spatial frequency characteristics of GSN/1 chickens showed poor scores at high frequency. No abnormal findings were observed ophthalmoscopically in the fundus of them. The amplitudes of a and b waves of the electroretinogram in GSN/1 chickens revealed no abnormal findings for xenon flash stimuli with different intensities. However, responses of the visual evoked potential in GSN/1 chickens were insensitive to xenon flash stimuli. Histologically, the retina of GSN/1 chickens was slightly hypoplastic and the retinal ganglion cells decreased in number, although there were no degenerative or reactive changes. The optic tectum, especially the stratum opticum and the stratum griseum et fibrosum superficiale were hypoplastic and contained reduced numbers of optic nerve fibers. The sublayers of the stratum griseum et fibrosum superficiale were disorganized, in which axons of the optic nerve were distributed irregularly. These findings suggest that visual impairment observed in the new mutant GSN/1 chicken may be related to developmental defects in the visual pathways, especially in the optic tectum. [ABSTRACT FROM AUTHOR]

The significance of glycogenosomes (glycogen bodies), frequently seen in peripheral neurites of aging rats, is unknown and their occurrence elsewhere in nervous tissue is poorly documented. During the course of another study these bodies were observed by light microscopy in the visual pathways of aging rats where they have not previously been noted, and this report documents their occurrence, localisation and changes in density with age. Using the periodic acid-Schiff stain, small brightly red-staining bodies, digested by diastase and containing β-glycogen particles, were seen in increasing numbers in the neuropil of the superior colliculi in brain sections from animals of ¶5 months of age onwards. From 1 year until more than ¶2 years of age they steadily became more numerous in the outer one third of the superior colliculus, but remained small, rarely exceeding 4 μm. They were also found at later times in small numbers lying singly in the optic tract, the optic chiasm and optic nerves, although rarely in lateral geniculate nuclei. Similar bodies were also found to accumulate with age in the retinal photoreceptor cell layer. Changes in their densities and size with age in both regions have been documented and it is suggested that, while their occurrence in retinal photoreceptor cells may be due to sustained light damage leading to mitochondrial oxidative stress, it is difficult to implicate this mechanism for their occurrence in retino-tectal nerve fibres. The role of physical trauma, suggested for the presence of these bodies in aging peripheral axons, can be excluded and they appear not to be related to polyglucosan bodies. [ABSTRACT FROM AUTHOR]

Intravesical Bacillus Calmette-Guérin (BCG) administration was used to treat bladder carcinoma in a woman in her 60s. Severe bilateral non-granulomatous anterior uveitis and gross papillitis developed subsequently. The severe BCG-induced bilateral uveitis and papillitis were treated with high dose oral corticosteroids, with topical steroids and cycloplegics. Resolution of her ocular symptoms and signs eventuated. On lumbar puncture, no evidence of systemic spread of the BCG was found. Visual acuity returned to 6/9 in each eye with subsequent resolution of papillitis. Repeat cystoscopy demonstrated no evidence of recurrent bladder tumour.Hypersensitivity reactions are well recognised with Tubercle bacilli While both hypersensitivity reactions and dissemination of BCG throughout the body have been previously documented, the literature demonstrates that this case is the first example in which papillitis and bilateral uveitis were the prominent ophthalmological features., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

True isolated sixth nerve palsy as the initial presentation of multiple sclerosis (MS) is rare. MS is a chronic inflammatory, immune-mediated disease of the central nervous system. This is the most common cause of neurological disability in young adults. Common symptoms include acute episodes of muscle weakness, altered sensation, balance and gait disturbances, visual loss and bladder dysfunction.Diagnosis of MS is supported with the incidence of symptomatic clinical episodes with subsequent cross-sectional imaging to confirm radiological lesions that are disseminated in space and time.In the following report, we discuss the case of a woman in her 30s who presented to ophthalmology with a sixth nerve palsy in the absence of ocular or systemic disease. This is the first presentation of MS, a rare clinical event., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To examine systematically how prechiasmal, chiasmal, and postchiasmal lesions along the visual pathway affect the respective pupillary responses to specific local monochromatic stimuli., Methods: Chromatic pupil campimetry (CPC) was performed in three patient groups (10 subjects with status after anterior ischemic optic neuropathy, 6 with chiasmal lesions, and 12 with optic tract or occipital lobe lesions (tumor, ischemia)) using red, low-intensity red, and blue local stimuli within the central 30° visual field. Affected areas - as determined by visual field defects revealed using conventional static perimetry - were compared with non-affected areas. Outcome parameters were the relative maximal constriction amplitude (relMCA) and the latency to constriction onset of the pupillary responses., Results: A statistically significant relMCA reduction was observed in the affected areas of postchiasmal lesions with red (p = 0.004) and low-intensity red stimulation (p = 0.001). RelMCA reduction in the affected areas seemed more pronounced for low-intensity red stimulation (46.5% mean reduction compared to non-affected areas; 36% for red stimulation), however statistically not significant. In prechiasmal lesions, a statistically significant latency prolongation could be demonstrated in the affected areas with low-intensity red stimulation (p = 0.015)., Conclusion: Our results indicate that the choice of stimulus characteristics is relevant in detecting defects in the pupillary pathway of impairment along the visual pathway, favoring red stimuli of low intensity over blue stimuli. Such knowledge opens the door for further fundamental research in pupillary pathways and is important for future clinical application of pupillography in neuro-ophthalmologic patients., (© 2021. The Author(s).)

We report a case of a man in his 50s who developed open-angle glaucoma following neodymium-doped yttrium aluminium garnet (YAG) laser vitreolysis. Despite attempts to control the pressure with topical medication and selective laser trabeculoplasty (SLT), surgical intervention using a Baerveldt glaucoma valve (BGV) was needed after which the intraocular pressure was controlled successfully. This rare but serious complication highlights the fact that in certain cases long-term monitoring of intraocular pressure is necessary following laser vitreolysis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

We have studied brain connectivity using a biologically inspired in silico model of the visual pathway consisting of the lateral geniculate nucleus (LGN) of the thalamus, and layers 4 and 6 of the primary visual cortex. The connectivity parameters in the model are informed by the existing anatomical parameters from mammals and rodents. In the base state, the LGN and layer 6 populations in the model oscillate with dominant alpha frequency, while the layer 4 oscillates in the theta band. By changing intra-cortical hyperparameters, specifically inhibition from layer 6 to layer 4, we demonstrate a transition to alpha mode for all the populations. Furthermore, by increasing the feedforward connectivities in the thalamo-cortico-thalamic loop, we could transition into the beta band for all the populations. On looking closely, we observed that the origin of this beta band is in the layer 6 (infragranular layers); lesioning the thalamic feedback from layer 6 removed the beta from the LGN and the layer 4. This agrees with existing physiological studies where it is shown that beta rhythm is generated in the infragranular layers. Lastly, we present a case study to demonstrate a neurological condition in the model. By changing connectivities in the network, we could simulate the condition of significant ( P < 0.001) decrease in beta band power and a simultaneous increase in the theta band power, similar to that observed in Schizophrenia patients. Overall, we have shown that the connectivity changes in a simple visual thalamocortical in silico model can simulate state changes in the brain corresponding to both health and disease conditions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sasi and Sen Bhattacharya.)

A man in his 20s presented to the neurosurgery department 2 years ago with headache and blurred vision. He was diagnosed to have a suprasellar mass on neuroimaging. Best-corrected visual acuity in the right eye was 6/36 and that in the left eye was 6/60. Automated visual fields showed a temporal hemianopia in the right eye and an advanced field defect in the left eye. His hormonal profile was normal, and he underwent partial excision of suprasellar tumour, which was a histopathologically proven paraganglioma (PGL). Subsequently, the patient underwent radiotherapy and his vision and visual fields showed improvement. Follow-up examination 3 years later showed a left retinal capillary hemangioblastoma (RCH), which was treated with green laser photocoagulation, resulting in complete sclerosis. This case is unique because of the extremely rare coexistence of a sellar PGL and RCH, which to our knowledge has not been reported so far., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Competing interests: None declared.

Glaucoma is a group of ophthalmologic conditions characterized by progressive retinal ganglion cell death, optic nerve degeneration, and irreversible vision loss. While intraocular pressure is the only clinically modifiable risk factor, glaucoma may continue to progress at controlled intraocular pressure, indicating other major factors in contributing to the disease mechanisms. Recent studies demonstrated the feasibility of advanced diffusion magnetic resonance imaging (dMRI) in visualizing the microstructural integrity of the visual system, opening new possibilities for non-invasive characterization of glaucomatous brain changes for guiding earlier and targeted intervention besides intraocular pressure lowering. In this review, we discuss dMRI methods currently used in visual system investigations, focusing on the eye, optic nerve, optic tract, subcortical visual brain nuclei, optic radiations, and visual cortex. We evaluate how conventional diffusion tensor imaging, higher-order diffusion kurtosis imaging, and other extended dMRI techniques can assess the neuronal and glial integrity of the visual system in both humans and experimental animal models of glaucoma, among other optic neuropathies or neurodegenerative diseases. We also compare the pros and cons of these methods against other imaging modalities. A growing body of dMRI research indicates that this modality holds promise in characterizing early glaucomatous changes in the visual system, determining the disease severity, and identifying potential neurotherapeutic targets, offering more options to slow glaucoma progression and to reduce the prevalence of this world's leading cause of irreversible but preventable blindness.