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Investigative Ophthalmology & Visual... Aug 2023Human albinos have a low visual acuity. This is partially due to the presence of spontaneous erroneous eye movements called pendular nystagmus. This nystagmus is present...
PURPOSE
Human albinos have a low visual acuity. This is partially due to the presence of spontaneous erroneous eye movements called pendular nystagmus. This nystagmus is present in other albino vertebrates and has been hypothesized to be caused by aberrant wiring of retinal ganglion axons to the nucleus of the optic tract (NOT), a part of the accessory optic system involved in the optokinetic response to visual motion. The NOT in pigmented rodents is preferentially responsive to ipsiversive motion (i.e., motion in the contralateral visual field in the temporonasal direction). We compared the response to visual motion in the NOT of albino and pigmented mice to understand if motion coding and preference are impaired in the NOT of albino mice.
METHODS
We recorded neuronal spiking activity with Neuropixels probes in the visual cortex and NOT in C57BL/6JRj mice (pigmented) and DBA/1JRj mice with oculocutaneous albinism (albino).
RESULTS
We found that in pigmented mice, NOT is retinotopically organized, and neurons are direction tuned, whereas in albino mice, neuronal tuning is severely impaired. Neurons in the NOT of albino mice do not have a preference for ipsiversive movement. In contrast, neuronal tuning in visual cortex was preserved in albino mice and did not differ significantly from the tuning in pigmented mice.
CONCLUSIONS
We propose that excessive interhemispheric crossing of retinal projections in albinos may cause the disrupted left/right direction encoding we found in NOT. This, in turn, impairs the normal horizontal optokinetic reflex and leads to pendular albino nystagmus.
Topics: Animals; Mice; Albinism; Mice, Inbred C57BL; Mice, Inbred DBA; Nystagmus, Optokinetic; Nystagmus, Pathologic; Pretectal Region; Retinal Ganglion Cells; Visual Cortex; Visual Pathways
PubMed: 37548962
DOI: 10.1167/iovs.64.11.9 -
Nan Fang Yi Ke Da Xue Xue Bao = Journal... Jul 2023To improve the classical 4-vessel occlusion (4VO) model established by Pulsinelli and Brierley.
OBJECTIVE
To improve the classical 4-vessel occlusion (4VO) model established by Pulsinelli and Brierley.
METHODS
Thirty-two male SD rats were randomized into sham operation group, I4VO-Con10 group, I4VO-Int10 group and I4VO-Int15 group. The sham surgery group underwent exposure of the bilateral vertebral arteries and carotid arteries without occlusion to block blood flow. The I4VO-Con10 group experienced continuous ischemia by occluding the bilateral vertebral arteries and carotid arteries for 10 minutes followed by reperfusion for 24 hours. The I4VO-Int10 and I4VO-Int15 groups were subjected to intermittent ischemia. The I4VO- Int10 group underwent 5 minutes of ischemia, followed by 5 minutes of reperfusion and another 5 minutes of ischemia, and then reperfusion for 24 hours. The I4VO-Int15 group experienced 5 minutes of ischemia followed by two cycles of 5 minutes of reperfusion and 5 minutes of ischemia, and then reperfusion for 24 hours. The regional cerebral blood flow (rCBF) was monitored with laser Doppler scanning, and survival of the rats was observed. HE staining was used to observe hippocampal pathologies to determine the optimal method for modeling. Another 48 rats were randomized into 6 groups, including a sham operation group and 5 model groups established using the optimal method. The 5 I4VO model groups were further divided based on the reperfusion time points (1, 3, 7, 14, and 28 days) into I4VO-D1, I4VO-D3, I4VO-D7, I4VO- D14, and I4VO- D28 groups. Body weight changes and survival of the rats were recorded. HE staining was used to observe morphological changes in the hippocampal, retinal and optic tract tissues. The Y-maze test and light/dark box test were used to evaluate cognitive and visual functions of the rats in I4VO-D28 group.
RESULTS
Occlusion for 5 min for 3 times at the interval of 5 min was the optimal method for 4VO modeling. In the latter 48 rats, the body weight was significantly lower than that of the sham-operated rats at 1, 3, 7, 14 and 28 days after modeling without significant difference in survival rate among the groups. The rats with intermittent vessel occlusion exhibited progressive deterioration of hippocampal neuronal injury and neuronal loss. Cognitive impairment was observed in the rats in I4VO-D28 group, but no obvious ischemic injury of the retina or the optic tract was detected.
CONCLUSION
The improved 4VO model can successfully mimic the main pathological processes of global cerebral ischemia-reperfusion injury without causing visual impairment in rats.
Topics: Rats; Male; Animals; Rats, Sprague-Dawley; Brain Ischemia; Cerebral Infarction; Reperfusion Injury; Body Weight
PubMed: 37488802
DOI: 10.12122/j.issn.1673-4254.2023.07.16 -
International Journal of Molecular... Feb 2024We recently identified PKN1 as a developmentally active gatekeeper of the transcription factor neuronal differentiation-2 (NeuroD2) in several brain areas. Since NeuroD2...
We recently identified PKN1 as a developmentally active gatekeeper of the transcription factor neuronal differentiation-2 (NeuroD2) in several brain areas. Since NeuroD2 plays an important role in amacrine cell (AC) and retinal ganglion cell (RGC) type formation, we aimed to study the expression of NeuroD2 in the postnatal retina of WT and animals, with a particular focus on these two cell types. We show that PKN1 is broadly expressed in the retina and that the gross retinal structure is not different between both genotypes. Postnatal retinal NeuroD2 levels were elevated upon knockout, with retinae showing more NeuroD2 cells in the lower portion of the inner nuclear layer. Accordingly, immunohistochemical analysis revealed an increased amount of AC in postnatal and adult retinae. There were no differences in horizontal cell, bipolar cell, glial cell and RGC numbers, nor defective axon guidance to the optic chiasm or tract upon knockout. Interestingly, we did, however, see a specific reduction in SMI-32 α-RGC in retinae. These results suggest that PKN1 is important for retinal cell type formation and validate PKN1 for future studies focusing on AC and α-RGC specification and development.
Topics: Animals; Retina; Retinal Ganglion Cells; Amacrine Cells; Optic Chiasm; Transcription Factors
PubMed: 38474095
DOI: 10.3390/ijms25052848 -
Frontiers in Aging Neuroscience 2024The aim of our study was to examine the alterations in microstructure in patients with coronary artery disease (CAD) and cognitive impairment (CI) using diffusion...
OBJECT
The aim of our study was to examine the alterations in microstructure in patients with coronary artery disease (CAD) and cognitive impairment (CI) using diffusion kurtosis imaging (DKI). Additionally, we aimed to investigate the potential correlation between DKI parameters and cognitive function.
MATERIALS AND METHODS
A total of 28 CAD patients and 30 healthy controls (HC) were prospectively enrolled in our study. All participants underwent routine and diffusion sequences of head imaging. DKE software was utilized to generate various diffusion kurtosis imaging parameters (DKI), including kurtosis fractional anisotropy (KFA), mean kurtosis (MK), axial kurtosis (AK), radial kurtosis (RK), fractional anisotropy (FA), and mean diffusivity (MD). Nonparametric tests were conducted using tract-based spatial statistics (TBSS) to compare the parameter values between the two groups. The parameter values of the significantly different fiber tracts were extracted and correlated with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores.
RESULTS
Compared to the HC group, patients with coronary artery disease exhibited significant reductions in FA values in the bilateral Superior corona radiata, bilateral Anterior corona radiata, bilateral Posterior corona radiata, corpus callosum, left Posterior thalamic radiation, right Posterior limb of internal capsule, Anterior limb of internal capsule, and Cerebral peduncle, as well as in the left Superior longitudinal fasciculus. Additionally, KFA values decreased in the bilateral Anterior corona radiata, bilateral Anterior limb of internal capsule, and Genu of the corpus callosum. The MK values decreased in the right Posterior corona radiata, Retrolenticular part of the internal capsule, Posterior thalamic radiation (including optic radiation), Superior longitudinal fasciculus, and left Posterior thalamic radiation (including optic radiation). Moreover, the RK values decreased in the bilateral Retrolenticular part of the internal capsule, right Posterior thalamic radiation (including optic radiation), and Superior longitudinal fasciculus, as well as in the left Superior longitudinal fasciculus and Posterior thalamic radiation (including optic radiation) ( < 0.01, TFCE corrected), while no significant differences were observed in other parameter values ( > 0.01, TFCE corrected). The FA values of the right posterior limb of the internal capsule ( = 0.610, = 0.001) and the right cerebral peduncle ( = 0.622, < 0.001) were positively correlated with MMSE scores. Additionally, a significant correlation between kurtosis and diffusion coefficient parameters (FA and KFA) was observed.
CONCLUSION
CAD patients showed radial shrinkage and complexity of brain white matter microstructure. Whole-brain white matter analysis based on TBSS DKI can objectively reflect the characteristics of white matter damage in CAD patients, providing a basis for the auxiliary diagnosis of CAD with CI.
PubMed: 38425783
DOI: 10.3389/fnagi.2024.1301826 -
Child's Nervous System : ChNS :... Apr 2024Intracranial teratoma represents a rare neoplasm, occurring predominantly during childhood. Characteristic symptoms depend on the location but are mainly hydrocephalus,... (Review)
Review
BACKGROUND
Intracranial teratoma represents a rare neoplasm, occurring predominantly during childhood. Characteristic symptoms depend on the location but are mainly hydrocephalus, visual disturbances, hypopituitarism, and diabetes insipidus. Initial diagnosis can be challenging due to similar radiological features in both teratomas and other lesions such as craniopharyngiomas. Gross total resection is recommended if feasible and associated with a good prognosis.
CASE DESCRIPTION
A 10-year-old girl presented with newly diagnosed growth retardation, fatigue, cephalgia and bilateral hemianopia. Further laboratory analysis confirmed central hypothyroidism and hypercortisolism. Cranial magnetic resonance imaging showed a cystic space-occupying lesion in the sellar and suprasellar compartment with compression of the optic chiasm without hydrocephalus present, suspicious of craniopharyngioma. Subsequently, an endonasal endoscopic transsphenoidal near-total tumor resection with decompression of the optic chiasm was performed. During postoperative recovery the patient developed transient diabetes insipidus, the bilateral hemianopia remained unchanged. The patient could be discharged in a stable condition, while hormone replacement for multiple pituitary hormone deficiency was required. Surprisingly, histopathology revealed conspicuous areas of skin with formation of hairs and squamous epithelia, compatible with a mature teratoma.
CONCLUSIONS
We present an extremely rare case of pediatric sellar teratoma originating from the pituitary gland and a review of literature focusing on the variation in presentation and treatment. Sellar teratomas are often mistaken for craniopharyngioma due to their similar radiographic appearances. However, the primary goal of treatment for both pathologies is to decompress eloquent surrounding structures such as the optic tract, and if applicable, resolution of hydrocephalus while avoiding damage to the pituitary stalk and especially the hypothalamic structures. If feasible, the aim of surgery should be gross total resection.
Topics: Female; Humans; Child; Craniopharyngioma; Hemianopsia; Pituitary Neoplasms; Hypopituitarism; Diabetes Insipidus; Central Nervous System Neoplasms; Teratoma; Hydrocephalus
PubMed: 38276973
DOI: 10.1007/s00381-024-06296-w -
Frontiers in Neuroanatomy 2024The amygdala is a noticeable bilateral structure in the medial temporal lobe and it is composed of at least 13 different nuclei and cortical areas, subdivided into the...
INTRODUCTION
The amygdala is a noticeable bilateral structure in the medial temporal lobe and it is composed of at least 13 different nuclei and cortical areas, subdivided into the deep nuclei, the superficial nuclei, and the remaining nuclei which contain the central nucleus (CeA). CeA mediates the behavioral and physiological responses associated with fear and anxiety through pituitary-adrenal responses by modulating the liberation of the hypothalamic Corticotropin Releasing Factor/Hormone.
METHODS
Five dolphins of three different species, belonging to the family Delphinidae (three striped dolphins, one common dolphin, and one Atlantic spotted dolphin), were used for this study. For a precise overview of the CeA's structure, thionine staining and the immunoperoxidase method using calbindin D-28k were employed.
RESULTS
CeA extended mainly dorsal to the lateral nucleus and ventral to the striatum. It was medial to the internal capsule and lateral to the optic tract and the medial nucleus of the amygdala.
DISCUSSION
The dolphin amygdaloid complex resembles that of primates, including the subdivision, volume, and location of the CeA.
PubMed: 38899230
DOI: 10.3389/fnana.2024.1382036 -
Frontiers in Neuroscience 2023Multiple sclerosis (MS) is a chronic inflammatory demyelinating and degenerative disease of the central nervous system which, when it begins before the age of 18, is...
INTRODUCTION
Multiple sclerosis (MS) is a chronic inflammatory demyelinating and degenerative disease of the central nervous system which, when it begins before the age of 18, is defined as paediatric MS. Most common clinical presentations include long tract involvement, brainstem/cerebellum syndromes, optic neuritis and acute disseminated encephalomyelitis. Paediatric-onset MS typically has a more inflammatory-active course and a higher lesion burden in imaging studies, but an extensive post-relapse recovery, with a slower long-term disability progression. The first demyelinating clinical attack occurs before 10 years old in less than 1% of patients, and, in this special population, the condition has particularities in clinical presentation, differential diagnosis, diagnostic assessment, current treatment options and outcome.
CLINICAL CASES
We present the cases of four Caucasian children (2 girls) diagnosed with relapsing-remitting MS before the age of ten, with a mean age at the time of the first relapse of 7.4 ± 2.4 years. Clinical presentation included optic neuritis, myelitis, brainstem syndrome, and acute disseminated encephalomyelitis. Baseline MRI identified several lesions, frequently large and ill-defined. Two patients were included in clinical trials and two patients remain in clinical and imaging surveillance.
CONCLUSION
Diagnosis of MS before the age of 10 years is rare, but it has significant long-term physical and cognitive consequences, as well as a substantial impact on the current and future quality of life of the child and family. Early and correct diagnosis is essential. Prospective, randomized, large cohort studies are needed to assess the efficacy and safety of disease-modifying treatments in children under the age of ten.
PubMed: 38174051
DOI: 10.3389/fnins.2023.1297171 -
Radiology Case Reports Aug 2023Glioma has been previously known as the most common adult brain tumor. Glioma of the optic pathway is predominated by low-grade neoplasms. High-grade glioma in adults is...
Glioma has been previously known as the most common adult brain tumor. Glioma of the optic pathway is predominated by low-grade neoplasms. High-grade glioma in adults is extremely rare. In this study, we present the case of a 46-year-old male patient who developed glioblastoma of the optic chiasm extending along the optic tract. This study aims to discuss several common differential diagnoses of nontumor diffuse lesions in the optic pathway and their clinical symptoms and magnetic resonance imaging findings, which could help navigate management.
PubMed: 37273722
DOI: 10.1016/j.radcr.2023.05.010 -
BioRxiv : the Preprint Server For... Jan 2024Traumatic brain injuries (TBI) present a major public health challenge, demanding an in-depth understanding of age-specific signs and vulnerabilities. Aging not only...
Traumatic brain injuries (TBI) present a major public health challenge, demanding an in-depth understanding of age-specific signs and vulnerabilities. Aging not only significantly influences brain function and plasticity but also elevates the risk of hospitalizations and death following repetitive mild traumatic brain injuries (rmTBIs). In this study, we investigate the impact of age on brain network changes and white matter properties following rmTBI employing a multi-modal approach that integrates resting-state functional magnetic resonance imaging (rsfMRI), graph theory analysis, diffusion tensor imaging (DTI), and Neurite Orientation Dispersion and Density Imaging (NODDI). Utilizing the CHIMERA model, we conducted rmTBIs or sham (control) procedures on young (2.5-3 months old) and aged (22-month-old) male and female mice to model high risk groups. Functional and structural imaging unveiled age-related reductions in communication efficiency between brain regions, while injuries induced opposing effects on the small-world index across age groups, influencing network segregation. Functional connectivity analysis also identified alterations in 79 out of 148 brain regions by age, treatment (sham vs. rmTBI), or their interaction. Injuries exerted pronounced effects on sensory integration areas, including insular and motor cortices. Age-related disruptions in white matter integrity were observed, indicating alterations in various diffusion directions (mean, radial, axial diffusivity, fractional anisotropy) and density neurite properties (dispersion index, intracellular and isotropic volume fraction). Inflammation, assessed through Iba-1 and GFAP markers, correlated with higher dispersion in the optic tract, suggesting a neuroinflammatory response in aged animals. These findings provide a comprehensive understanding of the intricate interplay between age, injuries, and brain connectivity, shedding light on the long-term consequences of rmTBIs.
PubMed: 38328104
DOI: 10.1101/2024.01.25.577316 -
Cureus Jan 2024We present a case of an adult patient experiencing progressive visual loss. An initial presentation was concerning for neuromyelitis optica with optic chiasm...
We present a case of an adult patient experiencing progressive visual loss. An initial presentation was concerning for neuromyelitis optica with optic chiasm involvement. However, persistent contrast enhancement observed in follow-up brain and orbit images raised suspicion for optic tract malignant neoplasm. Histopathological evolution of optic nerve biopsy confirmed the diagnosis of an optic chiasm glioma. The patient was then referred to oncology for chemotherapy.
PubMed: 38313959
DOI: 10.7759/cureus.51614