Optic Radiation

The latter was used to study optic radiation by calculating water apparent diffusion coefficients (ADC). ADC values of optic radiations in patients were significantly higher than controls (P < 0.01). Visual pathway involvement is found consistently in FRDA, being previously underestimated, and we here document that it also involves the optic radiations.  

DT fiber tractography provides valuable information on the axonal density of postgeniculate fibers (optic radiation), and fMRI studies of patients with primary open-angle glaucoma (POAG) have demonstrated alterations involving the human visual cortex that are consistent with clinically documented losses of visual function.  

This study tests the hypothesis that a correlation exists between the microstructure of the optic radiation and visual performance in premature neonates. DTI fiber tracking methods were developed to delineate the optic radiations and segment the tract into anterior, middle, and posterior regions. Structural development and spatial heterogeneity in the delineated optic radiations were quantitatively assessed with diffusion tensor parameters including fractional anisotropy (FA), directionally averaged diffusivity (D(av)), parallel diffusivity (lambda(1)), and transverse diffusivity (lambda( perpendicular)). Regression analysis was used to examine the relationship between neonatal visual performance and the microstructure of the optic radiation. RESULTS: Fractional anisotropy within the optic radiation was observed to increase with GA (P < .0001). D(av), parallel diffusivity, and transverse diffusivity within the optic radiation each decreased with GA (P < .0003, P < .02, and P < .0001, respectively). The anterior segment of the optic radiation exhibited higher FA and lower D(av), parallel diffusivity, and transverse diffusivity (P < .005 each) than within the middle and posterior segments. optic radiation fractional anisotropy correlated significantly with scores from the visual fixation tracking assessment, independent of GA (P < .006). CONCLUSIONS: This study detected a significant link between the tissue architecture of the optic radiation and visual function in premature neonates..  

RESULTS: In 16 patients (three cavernomas, 13 gliomas), major white matter tracts (pyramidal tract, n = 14; optic radiation, n = 2) were visualized intraoperatively with a standard navigation system. CONCLUSION: Fiber tract data can be reliably integrated into a standard neuronavigation system, allowing for intraoperative visualization and localization of major white matter tracts such as the pyramidal tract or optic radiation..  

OBJECTIVE: Meyer's loop, the most vulnerable part of the optic radiations during approaches to the temporomedial region, extends to the tip of the temporal horn and is often encountered in epilepsy surgery. CONCLUSION: We have shown that there is a considerable risk of having visual field deficits after standard transsylvian selective amygdalohippocampectomy owing to the interruption of the anterior bundle of the optic radiation fibers, which most likely occurs while opening the temporal horn through the inferior limiting sulcus of the insula..  

As a risk factor for developing WS, we propose the clinical symptom of PDG with characteristic occipital AFA visible in the EEG, both of which represent damage to the occipital region including the optic radiation..  

RESULTS: Subjects with BD vs controls had significantly greater FA (t > 3.0, P optic radiation (increased longitudinal diffusivity), and right anterothalamic radiation (no significant diffusivity change). Among subjects with BD, significant negative correlations (P < .01) were found between age and FA in bilateral uncinate fasciculi and in the right anterothalamic radiation, as well as between medication load and FA in the left optic radiation. Decreased FA (P < .01) was observed in the left optic radiation and in the right anterothalamic radiation among subjects with BD taking vs those not taking mood stabilizers, as well as in the left optic radiation among depressed vs remitted subjects with BD.  

The cerebral peduncle, the middle cerebellum, and cingulum had the highest variation in FA, while fornix, optic radiation, and optic tract had the highest variation in ADC.  

Results: Subjects with diabetes had significantly lower mean fractional anisotropy than control subjects in the posterior corona radiata and the optic radiation (p<0.002).  

Objective: Using a fiber-dissection technique, our aim is to study the fiber bundles of the optic radiation. In the middle temporal gyrus approach, resection that is taken through the lateral wall of the temporal horn more than 55-60 mm behind the temporal pole may cross the optic radiation during their course here on the lateral wall. Conclusion: The presented fiber dissection study clarifies the relationship of optic radiation.  

Using diffusion tensor (DT) tractography, we quantified optic radiation (OR) structural changes in seven migraine patients with (MA) and eight without visual aura (MoA) and their relation to clinical manifestations and T2-visible burden.  

OBJECT: The aim of this study was to use diffusion tensor tractography (DTT) to define the 3D relationships of the uncinate fasciculus, anterior commissure, inferior occipitofrontal fasciculus, inferior thalamic peduncle, and optic radiation and to determine the positioning landmarks of these white matter tracts. On the inferior limiting sulcus, this point is the posterior limit of the optic radiation, and the temporal stem begins at the limen insulae and ends at the posteroinferior insular point. Most of the optic radiation crosses the postmedian two thirds of the temporal stem. CONCLUSIONS: On the inferior limiting sulcus, the posteroinferior insular point is a reliable landmark of the posterior limit of the optic radiations.  

OBJECTIVE: To study the fractional anisotropy (FA) and the architecture of the optic radiation fiber tracts of normal adults with magnetic resonance (MR) diffusion tensor imaging (DTI). FA and the mean diffusivity (MD) of the optic radiation were measured in the directional encoded color (DEC) maps. The architecture of the optic radiation fiber tracts were displayed with the software of diffusion tensor fiber tracking. RESULTS: In all subjects, the optic radiation could be readily identified in the DEC maps. No significant differences were found in the FA or MD value of the bilateral optic radiation (P>0.05). Diffusion tensor tractography (DTT) demonstrated that the 3 bundles of the optic radiation fibers were located in the lateral sagittal stratum, passing from the lateral geniculate body of the thalamus to the primary visual cortex. CONCLUSION: As a novel method to study the relationship between visual function and optic pathway, DTI and DTT can show the FA and architecture of the optic radiation..  

Both groups showed significant positive correlations of the NoGo-microstate duration with the white matter signal in the superior frontal region, the optic radiation, the posterior cingulate, and the inferolateral fascicle.  

The aims of this study are to investigate whether the integrity of corpus callosum (CC), cingulum, uncinate fasciculus (UF), optic radiation (OR) and corticospinal tract (CST) are damaged in patients with MR, and to determine the correlations between the integrity of these tracts and full scale intelligence quotient (FSIQ) in both patients and controls.  

Comparison of patients showing a RAPD vs those not showing a RAPD revealed that a region including the course of the optic radiation at its early beginning in the temporal white matter is commonly associated with a RAPD.  

The term blindsight, coined by Larry Weiskrantz, describes those discrimination abilities that can be elicited with visual stimuli restricted to the blindfield of a patient with occipital brain lesion or damaged optic radiation.  

Using diffusion tensor imaging, we measured water diffusion-related changes in the optic radiation contralateral to occipital lobe ablation in children with intractable epilepsy. Fiber bundles representing optic radiation were tracked. In the surgical group, fractional anisotropy values of optic radiation contralateral to the side of resection exhibited a significant positive partial correlation (r = 0.752, P = 0.019) with duration of time between surgery and diffusion tensor imaging acquisition, after controlling for age. After unilateral resection of the occipital lobe, the contralateral optic radiation undergoes significant changes in anisotropy.  

PURPOSE: To prospectively evaluate diffusion indexes of the corticospinal tract (CST), corpus callosum (CC), optic radiation (OR), and cingulum in patients with neuromyelitis optica (NMO) without visible lesions in the brain.  

One case was followed-up at 3 month of age, he developed normally, but delayed myelination was found on posterior limb of internal capsule and optic radiation without occipital and parietal cerebral atrophy.  

OBJECT: No definitive method of preventing visual field deficits after stereotactic radiosurgery for lesions near the optic radiation (OR) has been available so far.  

Planning, which was performed with the neuronavigator, was based on analysis of the location of the course of the main white matter tracts adjacent to the lesion (pyramidal tract, optic radiation and arcuate fasciculus). In the remaining 17 patients, the symptoms were related to involvement of the pyramidal tract, arcuate fasciculus or optic radiation.  

Moreover, with sufficiently small NIR detector-source distance, the contribution of the optic radiation propagated within the SAS to the total signal received is negligibly low, which gives a basis for estimation of the modulatory influence of blood circulation within the superficial skin layer on the total intensity of the backscattered radiation.  

INTRODUCTION: Temporal lobe resection for epilepsy involves a risk of damaging the anterior part of the optic radiation, Meyer's loop, causing a contralateral upper quadrant visual field defect. Diffusion tensor imaging and tractography were used to visualize the optic radiation.  

Apparent diffusion coefficient was higher in the severe injury group at the second MRI in the central and occipital white matter, and corona radiata; FA was lower in optic radiation compared to controls.  

We detected 9 circumscribed significant clusters (p< .01) with lower IC values in low performers than in high performers, with centers of gravity located in left and right superior temporal region, corpus callosum, left superior longitudinal fascicle, and left optic radiation.  

The purpose of the present study was to evaluate the influence of intracranial AVM on corticospinal tract and optic radiation tractography. Perinidal fractional anisotropy (FA) and number of voxels along the reconstructed corticospinal and optic radiation tracts were measured, and left-to-right asymmetry indices (AIs) for those values were quantified. RESULTS: In patients without hemorrhage, AI of optic radiation volume (P<.0001), AI of perinidal FA along corticospinal tract (P=.006), and optic radiation (P=.01) differed significantly between groups. In patients associated with hemorrhage, AI of corticospinal tract volume (P=.01), AI of perinidal FA along corticospinal tract (P=.04), and optic radiation (P=.004) differed significantly between groups. CONCLUSIONS: Corticospinal tract and optic radiation tractography were visualized in patients with AVM.  

The results showed that, relative to the SC, the EB exhibits significantly reduced WM volumes in the optic tract and optic radiation and significant GM losses in the early visual cortex. The reduction of WM volume in the optic radiation of the EB was found be modulated by both the age at blindness onset and the duration of blindness.  

MRI showed patchy lesions in the callosum, right optic radiation, both side thalamus (left > right), left cerebral peduncle, and spinal cord of cervical to the thoracal portion.  

Three dimensional visualization of the white matter fibers such as corticospinal (pyramidal) tract, optic radiation and arcuate fasciculus with relationship to brain tumors such as gliomas was extremely helpful for preoperative evaluation and intraoperative navigation.  

Mean FA, MD, and TD were recorded for regions of interest placed within the corpus callosum, corticospinal tract, putamen, optic radiation, and ventricular cerebral spinal fluid.  

MRI scan revealed multiple enhancing lesions involving the optic chiasm, left optic tract, right lateral geniculate body, and right optic radiation in the temporal lobe.  

We performed diffusion tensor imaging (DTI) with a clinical 1.5 T MR machine to visualize optic radiation. With patients who were clinically expected to show disorder of optic radiation, these visualizations were consistent with their pathologies. It was suggested that this new DTI technique is useful for estimating functional disorder of optic radiation..  

The lesion locations in congruent HH vs incongruent HH included occipital lobe in 47.9% vs 21.3%, occipital lobe and optic radiations in 8.3% vs 5.6%, optic radiations in 32.4% vs 50.6%, optic tract in 7.2% vs 16.3%, and other locations in 4.2% vs 6.3% (P < .0001). Although there was a trend toward more congruent HH for lesions of the posterior visual pathways (P < .001), 50% of optic tract lesions and 59% of optic radiation lesions produced congruent HH.  

RESULTS: Fractional anisotropy reductions in schizophrenia patients were confirmed in the left cingulum, anterior thalamic radiation, fronto-occipital and inferior longitudinal fasciculi, as well as bilaterally in the corpus callosum, anterior and posterior limbs of internal capsule, superior longitudinal fasciculus, optic radiation, and frontotemporal extrafascicular white matter. Anisotropy reductions were more extensive in patients with poor outcomes ("Kraepelinian"), particularly in the posterior corpus callosum, fronto-occipital fasciculus, left optic radiation and frontotemporal white matter.  

PURPOSE: To detect the abnormalities of the optic radiation (OR) in children with amblyopia by diffusion tensor imaging (DTI) and tractography.  

OBJECT: In this study, the authors used a fiber-dissection technique to describe the optic radiation. The optic radiation, also known as the Gratiolet radiation, extended from the lateral geniculate body to the calcarine fissure. The breadth of the optic radiations, one on each side of the brain, averaged 17 mm at the level of the inferior horn (range 15-18 mm). This tract could be divided into three main segments: the anterior or Meyer loop, the body, and the end of the optic radiation. The knowledge gained by studying this particular anatomy will help prevent injury to the optic radiations during neurosurgery..  

BACKGROUND AND PURPOSE: Knowing the exact location of the optic radiation preoperatively is important for surgery of the temporal lobe. We hypothesized that a greater number of motion-probing gradients (MPGs) would provide better results of diffusion tensor (DT) fiber tractography of the optic radiation. To test this hypothesis, this study evaluated differences in DT fiber tractography of the optic radiation under different MPG settings. Fibers penetrating both ROIs were considered as the optic radiation. RESULTS: The optic radiation was well visualized in full length by DT fiber tractography in 20 of 24 hemispheres (83%). CONCLUSION: DT fiber tractography can frequently depict almost the entire optic radiation. MPG number does not exert any significant effect on visualization of the optic radiation, and 6-directional MPG is thus sufficient for this purpose..  

He demonstrated a sequence of closure of the cranial sutures, and he identified and named the optic radiation.  

Genes influenced individual differences in left and right superior occipitofrontal fascicle (heritability up to 0.79 and 0.77), corpus callosum (0.82, 0.80), optic radiation (0.69, 0.79), corticospinal tract (0.78, 0.79), medial frontal cortex (0.78, 0.83), superior frontal cortex (0.76, 0.80), superior temporal cortex (0.80, 0.77), left occipital cortex (0.85), left postcentral cortex (0.83), left posterior cingulate cortex (0.83), right parahippocampal cortex (0.69), and amygdala (0.80, 0.55).  

MR images showed lesions of the optic radiation, but primary visual cortical areas were intact.  

Region of interest (ROI) analysis of MD and FA was also performed in WM regions connected with the spinal white matter tracts or optic nerve (including medulla oblongata, cerebral peduncle, internal capsule, and optic radiation), in corpus callosum without direct connection with them, and in some GM regions.  

Tumor involvement of the following structures was associated with incomplete resection: corpus callosum, corticospinal tract, insular lobe, middle cerebral artery, motor cortex, optic radiation, visual cortex, and basal ganglia (P < .05 for all).  

The purposes of this study were to examine the microsurgical anatomy of the atrium of the lateral ventricle and the optic radiation and to define the differences in the exposure obtained by various surgical approaches. The relationship between the optic radiation and the atrium was studied using the white matter fiber dissection technique. RESULTS: The medial and inferior walls of the atrium were free from optic radiation fibers.  

RESULTS: In 16 patients (three cavernomas, 13 gliomas), major white matter tracts (pyramidal tract, n = 14; optic radiation, n = 2) were visualized intraoperatively with a standard navigation system. CONCLUSION: Fiber tract data can be reliably integrated into a standard neuronavigation system, allowing for intraoperative visualization and localization of major white matter tracts such as the pyramidal tract or optic radiation..  

The lesion was occipital in 14 (12.5%) patients, associated with optic radiation in 26 (23.2%) and the optic tract in 12 (10.7%), and multiple in 60 (53.6%).  

The areas were localized to the frontal gyral white matter, temporal gyral white matter, optic radiation, and others (corpus callosum, septum pellucidum, fasciculus subcallosus, and external capsule), with a greater distribution in the gyral white matter.  

By now it remains unknown, in how far the absence of afferent input in blindness affects also the organization of the optic radiation. Using diffusion tensor imaging (DTI), the non-invasive evaluation of large fiber tracts including the optic radiation has become possible. There was no axonal degeneration of the optic radiation in late onset acquired blindness.  

OBJECTIVE: To evaluate of the role of magnetic resonance (MR) tractography on the optic radiation with a 3-T MR unit in the surgery of cerebral arteriovenous malformation (AVM) in and around the visual pathway. All of the patients underwent 3-T tractography of optic radiation (OR) and neuro-ophthalmologic evaluation.  

However, this was not the case in a patient with a hemianopic visual field loss (quadrantanopia) as a result of damage to the optic radiation.  

The arcuate fibers, cingulum, superior and inferior longitudinal fasciculus, corticospinal tract, external capsule, optic radiation, and corpus callosum were all involved by intracranial tumors.  

CONCLUSION: Transsylvian and subtemporal approaches can reduce possible harm to parenchyma and optic radiation, whereas approaches to the temporal horn through the superior and middle temporal gyri will induce damage to parenchyma and optic radiation..  

We used this method in attempts to visualize the optic radiation and to examine the clinical applicability of this technique. We constructed 3 diopters fiber trajectories by tracking the direction of the fastest diffusion from the lateral geniculate nucleus, and then selected tracts on the basis of anatomical knowledge of the optic radiation. RESULTS: Our method successfully reconstructed the macroscopic 3 diopters architecture of the three major groups of optic radiation in all subjects. DT-MRI scanning required 7 minutes; preliminary images of the optic radiation could be obtained in approximately 20 minutes. CONCLUSIONS: Fiber-tracking enabled us to obtain information quickly on the 3 diopters course of the optic radiation in vivo. The finding that the fiber-tracking method underestimates the anterior extent of the optic radiations could prove to be an important limitation in the utility of this technique for preoperative planning.  

Location of the PAROI agrees with the angle of the upper loop of the optic radiation. The localization of the hyperechoic band supports the hypothesis that it represents part of the optic radiation.  

OBJECTIVE: This study examined the relationship of the optic radiation to the landmarks important in temporal lobe surgery. METHODS: The optic radiation was dissected by applying Klingler's fiber dissection technique to 20 formalin-fixed human hemispheres. The anterior edge of the optic radiation was located an average of 25 mm (range, 22-30 mm) behind the temporal pole. The optic radiation extended an average of 5 mm (range, 3-6 mm) anterior to the hippocampus head and 22 mm (range, 20-25 mm) anterior to the anterior edge of the lateral geniculate body. The optic radiation also extended an average of 2 mm (range, 1-3 mm) anterior to the tip of the temporal horn. The relationships of the optic radiation to important surgical landmarks are discussed. CONCLUSION: The optic radiation reached the anterior tip of the temporal horn. Resections that extend through the roof of the temporal horn more than 3 cm behind the temporal pole cross the anterior loop of the optic radiation..  

DTI maps suggest recovery of the optic radiation in the vicinity of the lesion. optic radiations in the injured hemisphere are more prominent in DTI at 20 months of age than in DTI at 12 months of age.  

A superior homonymous quadrantanopia is a well recognized complication of anterior temporal lobe resection and occurs because of disruption of the Meyer loop, the anterior part of the optic radiation. The authors used diffusion tensor imaging tractography to visualize the optic radiation before and after surgery, demonstrating the disruption of Meyer loop in a patient who developed a quadrantanopia. Preoperative imaging of the optic radiation will be useful in predicting visual field defects following temporal lobe resection..  

CRT was found to be significantly correlated with FA in projection and association pathways supporting visuospatial attention including the right optic radiation, right posterior thalamus, and right medial precuneus WM.  

OBJECT: The aim of this study was to define an anteromedial approach to the temporal horn via a transsylvian approach to avoid injury to the optic radiation fibers as well as the uncinate fasciculus. This route was compared with standard surgical approaches to the temporal horn, and their relationship to the optic radiation and uncinate fasciculus was reviewed. The dissection was continued until the optic radiation was encountered. Particular attention was paid to the relationship of the uncinate fasciculus with the optic radiation. An anteromedial transsylvian approach was defined to enter the temporal horn without injuring the optic radiation or the uncinate fasciculus. CONCLUSIONS: A transsylvian anteromedial approach through the pyriform cortex at the level of the anterior and superior surface of the uncus enables a safe entry into the temporal horn without injury to the optic radiation fibers or the main part of the uncinate fasciculus..  

The aim of this study was to combine the information of the visual evoked potentials (VEPs) and the anatomic navigation of the optic radiation by diffusion tensor imaging-based tractography for functional monitoring of the visual pathway. Diffusion tensor imaging-based tractography of the optic radiation was performed by selecting appropriate regions of interest and by fractional anisotropy. In Patient 2, the results of optic radiation tractography were imported to a neuronavigation system to better understand the spatial relationships between the lesions and the visual pathway (functional neuronavigation). RESULTS: In Patient 1, the lesion did not seem to be attached to the optic radiation, and VEP profiles remained stable during resection. In Patient 2, who had a lesion adjacent to the posterior horn of the lateral ventricle, VEPs suddenly diminished when resection reached the optic radiation as illustrated on the neuronavigation system.  

The pyramidal tract, corpus callosum and optic radiation were reconstructed and the exact location of a lesion with respect to these tracts was observed to design a reasonable surgical plan for preserving vital tracts while maximizing tumor resection. optic radiation was involved in three cases, all were type I with reduction of displacement.  

dilation and cupping of the optic nerve disc combined in all cases with affection of postgenicular visual paths (of optic radiation and/or striatal cortex) verified by neuroradiology, was most frequently (80.3%) encountered in children with PL.  

The MR imaging studies revealed that the eyeballs, optic nerves, optic chiasm, optic tracts and optic radiation were absent.  

This study investigated in vivo the optic radiations in patients affected by optic neuritis using fast marching tractography (FMT), a diffusion magnetic resonance imaging (MRI) fiber tracking method, and group mapping techniques, which allow statistical comparisons between subjects. The FMT algorithm was used to generate voxel-scale connectivity (VSC) maps in the optic radiations in each subject in native space. Group maps of the left and right optic radiations were created in the patient and control group in a standardized reference frame using statistical parametric mapping (SPM99). The reconstructed optic radiations in the patient group were localized more laterally in the posterior part of the tracts and more inferiorly than in the control group. These findings suggest that the group mapping techniques might be used to assess changes in the optic radiations in patients after an episode of optic neuritis.  

BACKGROUND AND PURPOSE: Visual defect due to optic radiation injury is a complication of temporal lobectomy for temporal epilepsy. To investigate whether diffusion tensor imaging can delineate the changes in optic radiations after lobectomy, we evaluated parameters on tensor images for optic radiations and correlated them with visual defect. We evaluated signals on T2-weighted images and parameters of tensor images, including fractional anisotropy (FA) and apparent diffusion coefficient (ADC), for the optic radiation in both the operated and intact side. RESULTS: On T2-weighted images, high signals in optic radiations were seen in four cases, occurring more than 4 weeks after surgery. The mean operated-to-intact side FA ratio in the optic radiation decreased according to severity of visual defect (group A, 0.88; group B, 0.89; group C, 0.73). CONCLUSION: optic radiation showed a decreased FA value in cases after temporal lobectomy. The FA value can be used for evaluating Wallerian degeneration of optic radiation even in the early stages after surgery..  

Although there are potential risks of damaging association fibers, optic radiation, the transverse gyrus of Heschl, and the parietal lobe, a thorough understanding of the topographical anatomy and careful dissection techniques can avoid morbidity.  

In this paper we report our experience with diffusion-weighted imaging (DWI) for optic radiation (OR) visualization during resection of tumors.  

Corpus callosum, fornix, anterior limb of the internal capsule, superior frontal gyrus, para-hippocampal gyrus, optic radiation and chiasma showed significant WMd reduction in nmTBI when compared to control subjects. In addition, we observed WMd reduction in the optic chiasma and in the optic radiations; this finding may reflect transneural degeneration along the visual pathway.  

The layer nearest to the origin of the optic radiation contained the smallest cells, and projected not only to V1, V2 and V3, but also, weakly, to the occipitotemporal area (OT, which is similar to primate middle temporal area) and the occipitoparietal area (OP, a "third tier" area located near the dorsal midline).  

PET with (11)C-flumazenyl revealed a reduction of (11)C-uptake in the demyelinated optic radiation, and only a slight reduction of (11)C-uptake in the primary visual cortex.  

In all four cases the central optic radiation was damaged between the lateral geniculate nucleus and the primary visual cortex.  

OBJECT: The aim of this anatomical study was to define more fully the three-dimensional (3D) relationships between the optic radiations and the temporal horn and superficial anatomy of the temporal lobe by using the Klingler white matter fiber dissection technique. Special attention was given to the optic radiation and to the sagittal stratum of which the optic radiation is a part. The trajectories of fibers in the optic radiation were specifically studied in relation to the lateral, medial, superior, and inferior walls of the temporal horn as well as to the superficial anatomy of the temporal lobe. In three of the hemispheres coronal sections were made so that the relationship between the optic radiation and the temporal horn could be studied more fully. 1) The optic radiation covered the entire lateral aspect of the temporal horn as it extends to the occipital horn. 2) The anterior tip of the temporal horn was covered by the anterior optic radiation along its lateral half. 3) The entire medial wall of the temporal horn was free from optic radiation fibers, except at the level at which these fibers arise from the lateral geniculate body to ascend over the roof of the temporal horn. 4) The superior wall of the temporal horn was covered by optic radiation fibers. 5) The entire inferior wall of the temporal horn was free from optic radiation fibers anterior to the level of the lateral geniculate body. CONCLUSIONS: Fiber dissections of the temporal lobe and horn demonstrated the complex 3D relationships between the optic radiations and the temporal horn and superficial anatomy of the temporal lobe. Based on the results of this study, the authors define two anatomical surgical trajectories to the temporal horn that would avoid the optic radiations. Lateral approaches to the temporal horn through the superior and middle gyri, based on the authors' findings, would traverse the optic radiations..  

An insight is gained into the three-dimensional course of the anterior loop of the optic radiation, the temporal stem, the anterior commissure, and the ansa peduncularis.  

Up to 17 degrees, it corresponds to striate projection of the "optic radiation" whilst more in periphery, there was paradoxical lateralisation of higher amplitude and shorter latency.  

It is most likely that both the optic radiation close to its termination in the dorsal parts of V1 and back-projecting fibers from V2 and V3 back to V1 generate phosphenes and scotomas..  

OBJECTIVE: Three-dimensional anisotropy contrast (3-DAC) magnetic resonance imaging and magnetoencephalography (MEG) of visually evoked magnetic fields (VEFs) were used to accurately localize the optic radiation and primary visual cortex before surgery for an occipital tumor. 3-DAC imaging showed that the right optic radiation was located along the superior and lateral surfaces of the lesion. CONCLUSION: Combined 3-DAC imaging and MEG can provide essential information about the optic radiation and primary visual cortex for planning the surgical treatment of occipital lobe tumors..  

In controls, we found left-higher-than-right anisotropic asymmetry in the anterior part of the corpus callosum, cingulum bundle, the optic radiation, and the superior cerebellar peduncle, and right-higher-than-left anisotropic asymmetry in the anterior limb of the internal capsule and the anterior limb's prefrontal regions, in the uncinate fasciculus, and in the superior longitudinal fasciculus.  

In the first step, voxels within large fiber tracts-such as corticofugal tracts (e.g., corticospinal tract) and the optic radiation-were segmented by starting the region-growing algorithm in the corpus callosum (CC) and erasing this major structure from the data set.  

Regions of interest were designated in frontal lobe, corona radiata, optic radiation, thalamus, pons, cerebellar vermis, and vitreous body. The SIR of the corona radiata and the optic radiation decreased significantly with GA (P < 0.05); after 34 weeks of gestation, they decreased sharply.  

As of now, it remains unknown, in how far this disorder also affects the organization of the optic radiation. Using diffusion-tensor imaging (DTI), the non-invasive evaluation of large fiber tracts including the optic radiation has become possible. One might presume, that, in order for the optic radiation to fully develop, an afferent input to the lateral geniculate body is necessarry..  

BACKGROUND AND PURPOSE: The MR anatomy of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop of the optic radiation, which traverse the temporal stem, is not well known.  

It was for the first time, that an expansion of the optic-nerve disk excavation was described in patients with the above syndrome; such expansion was conditioned by trans-synaptic neuron degeneration induced by lesions to optic radiation in view of prenatal of encephaloplastic processes. The changing brain white substance as projected by optic radiation was detected in all children by computer and magnetic resonance tomography.  

Involvement of the optic radiations is rare. DESIGN: This paper describes seven patients with NF-1 with gliomas involving the pregeniculate optic pathway in addition to the optic radiations. Patients with involvement of pregeniculate optic pathway and the optic radiations were identified. The other five had radiographic involvement of the optic radiations but did not undergo biopsy. CONCLUSIONS: Optic pathway gliomas in NF-1 may rarely involve the optic radiations. optic radiation involvement may signal a more aggressive optic pathway glioma in patients with neurofibromatosis-1..  

Whereas the trichromatic coefficients of the corticospinal tract greatly diminished between 6 and 12 hours after apparent brain death, the coefficients of the corpus callosum and the optic radiation decreased in less time, that is, between 1 and 6 hours.  

The functional activation in the intact hemisphere correlated clearly with the fiber tract of the optic radiation visualized with DTI. DTI confirmed the absence of the optic radiation in the damaged left hemisphere.  

A 17-year-old patient with a symptomatic cavernoma of the optic radiation underwent surgery supported by functional magnetic resonance imaging (fMRI), diffusion weighted magnetic resonance imaging (DWI) and navigated 3D-ultrasound. The optic radiation was delineated by means of DWI. The diffusion weigthed images were used for 3-dimensional reconstruction of the optic radiation. This is the first report of the combined use of fMRI, fiber tract imaging and 3D-ultrasound for the safe resection of an optic radiation lesion..  

This gender-related effect is noticeable in all brain areas but is most significant in the superior temporal gyrus, Heschl's gyrus, the adjacent white matter regions in the temporal stem and the knee of the optic radiation, the thalamus, and the posterior cingulate. Asymmetry decreases with age in the optic radiation, precentral gyrus, and angular gyrus.  

Our results suggest that in addition to the indirect connections of the occipito-temporal projection system: (i) a major associative connection between the occipital and anterior temporal lobe is provided by a fibre bundle whose origin, course and termination are consistent with classical descriptions of the ILF in man and with monkey visual anatomy; (ii) the tractography-defined ILF is structurally distinct from fibres of the optic radiation and from U-shaped fibres connecting adjacent gyri; (iii) it arises in extrastriate visual 'association' areas; and (iv) it projects to lateral and medial anterior temporal regions.  

CONCLUSION: Combined with the stereotactic navigation system, the ITS approach provides the least invasive amygdalohippocampectomy that preserves optic radiation.  

RESULTS: The main white matter fiber pathways, in particular the superior longitudinal fascicle, corpus callosum, tapetum, optic radiation, and internal capsule, were more clearly and easily identified on the superposed image than on the spin-echo T2-weighted image.  

Region-of interest measurements were performed at the following anatomic structures and represent gray-gray and white-white differentiations, respectively: globus pallidus externa versus globus pallidus interna, and optic radiation versus surrounding white matter.  

The first electrophysiological study of the human lateral geniculate nucleus (LGN), optic radiation, striate, and extrastriate visual areas is presented in the context of presurgical evaluation of three epileptic patients (Patients 1, 2, and 3). For Patient 1, electrode anatomical registration, structural magnetic resonance imaging, and electrophysiological responses confirmed the location of two contacts in the geniculate body and one in the optic radiation. Moreover, steady state visual-evoked potentials evoked by the unperceived but commonly experienced video-screen flicker were recorded in the LGN, optic radiation, and V1/V2 visual areas.  

CT and MRI of the brain showed a tumour deep in the right hemisphere near the thalamus and involving the optic radiation.  

The subtemporal approach should be selected for removal of these structures, and it does not interrupt the temporal stem and optic radiation.  

His brain MRI demonstrated infarction at the right anterior choroidal artery area, including right thalamus, caudate tail and optic radiation.  

OBJECTIVE: Transcortical approaches to the inferior horn often result in quadrant hemianopsia attributable to the injury to the optic radiation.  

The tracts that were visualized included the following: the arcuate fasciculus; superior and inferior longitudinal fasciculus; uncinate fasciculus; cingulum; external and extreme capsule; internal capsule; corona radiata; auditory and optic radiation; anterior commissure; corpus callosum; pyramidal tract; gracile and cuneatus fasciculus; medial longitudinal fasciculus; rubrospinal, tectospinal, central tegmental, and dorsal trigeminothalamic tract; superior, inferior, and middle cerebellar peduncle; pallidonigral and strionigral fibers; and root fibers of the oculomotor and trigeminal nerve.  

Magnetic resonance imaging (MRI) documented severe posterior lesions with wallerian degeneration of the optic radiation.  

Geniculate body and optic radiation were not involved by tumour diffusion.  

The optic radiation at the level of the trigone of the lateral ventricle was particularly frequently and severely affected. We conclude that the visual pathways are affected in a high proportion of patients with fatal closed head injury, nerve fibres in the optic radiations being particularly vulnerable.  

Thus, a common time-table could be established: At 1 month, myelin is visible on both T1w and T2w in the medulla oblongata, tegmentum pontis, cerebellar peduncles and vermis, quadrigeminal plate, decussation of superior cerebellar peduncles, thalamus, posterior limb of internal capsule, optic radiation, corona radiata.  

The mechanism of visual loss is likely to be a combination of ischaemic optic atrophy associated with a steal phenomenon and direct compression of the right optic radiation..  

In a longitudinal analysis of 50 infants followed for more than 5 sessions of weekly recordings, we found that the individual rapid decrease in the N1a latency, which may reflect the initiation of myelination in the optic radiation, most frequently occurs at around 37 weeks PMA, regardless of PNA.  

A negative signal change was found in the primary visual cortex including the lingual and fusiform gyri (BA 18/17) and the occipital white matter containing the optic radiation contralateral to the stimulated hemisphere.  

Periventricular leukomalacia affecting the optic radiation has now become the principal cause of visual impairment and dysfunction in children born prematurely.  

RESULTS: An age-dependent gradual increase in signal intensity was observed in optic radiation on the T1-weighted SE images, indicating progression of white matter myelination.  

Myelination in the cerebral corticospinal tract, optic radiation, and corpus callosum was observed in three cases of classic PMD with PLP duplication.  

In this paper, we present population maps of the optic radiation and the lateral geniculate body as a first example of this mapping strategy. A more than twofold variability of size in the interhemispheric extension of the optic radiation and the lateral geniculate body is found even after normalization of absolute brain size.  

It is well known that a lesion in the optic radiation or striate cortex leads to blind visual regions in the retinotopically corresponding portion of the visual field.  

spastic CP (involvement of motor tracts), mental retardation (bilateral extensive white matter reduction or cerebellar atrophy) and severe visual impairment (severe optic radiation involvement).  

We used the new technique of MR tractography to demonstrate the effects of temporal lobectomy on the optic radiation. RESULTS: In the patient with hemianopia, a significant reduction of diffusion anisotropy (greater than mean+/-2 SD) consistent with wallerian degeneration was demonstrated in the optic radiation on the side of the temporal lobectomy, extending from the temporal to the occipital lobe. In the other patient with standard en bloc resection but clinically no hemianopia, the optic radiation was only marginally affected. In the third patient (amygdalocorticectomy), the diffusion anisotropy was within the normal range in the expected position of the optic radiation. CONCLUSIONS: Our findings show that MR tractography may be a useful tool to demonstrate wallerian degeneration in the optic radiation after temporal lobectomy in patients with hemianopia.  

BACKGROUND AND PURPOSE: Although abnormal hyperintensities are frequently observed at or around the optic radiation in elderly subjects, no previous reports have mentioned the clinical significance and pathologic changes of these hyperintensities. We evaluated the hyperintensity patterns of the optic radiation and its surrounding structures on T2-weighted MR images and compared these findings with pathologic observations and visual field measurements. METHODS: High-resolution coronal T2-weighted MR images of 102 consecutive patients (51-84 years old) were evaluated retrospectively for the presence and morphology of hyperintensities of the optic radiation (204 sides) and its surrounding structures. The histopathologic changes of the optic radiation and its surrounding structures were evaluated and correlated with the MR findings. RESULTS: Hyperintensities of the optic radiation or its surrounding structures or both were observed on 125 sides (93%) of 67 patients (61%), and linear/laminar hyperintensity of the optic radiation and the tapetum was the characteristic finding. Eleven (44%) of 25 pathologic specimens exhibited pallor of three anatomic layers (the external sagittal stratum or the optic radiation, the internal sagittal stratum, and the tapetum). No subjects with hyperintensity of the optic radiation had visual field abnormalities. CONCLUSION: Linear/laminar hyperintensity of the optic radiation and tapetum on T2-weighted images is common in elderly subjects, and may reflect differences in the internal structures and in the water content of three anatomic structures.  

One patient had only cafe-au-lait spots, while the other patient had severe manifestations of NF1 in form of kyphoscoliosis, requiring multiple laminectomies, vertiginous attacks and optic radiation glioma seen on MRI.  

Repetitive activation of the optic radiation also evoked both GABA(A) and GABA(B) receptor-mediated inhibitory postsynaptic potentials.  

Activated regions had lower FA than optic radiation white matter, supporting the hypothesis that most BOLD signal change occurs within the relatively isotropic cortical grey matter.  

The results show that only one subject with a lesion in the optic radiation had blindsight in two discrete areas of the affected visual field. Spared optic radiation fibers of the main (primary) geniculo-striate visual pathway were most likely to account for this finding..  

BACKGROUND/AIMS: Periventricular leucomalacia (PVL) is a lesion in the immature brain involving the optic radiation.  

RESULTS: Ten of 18 children had periventricular leukomalacia affecting the optic radiation, six had other lesions or malformations in the posterior visual pathways/cortex, but no child had visually impairing retinopathy of prematurity.  

The optic radiation, comprising the external sagittal stratum, appeared as an intermediate to slightly high-intensity layer on T2-weighted images and a low-intensity layer on T1-weighted images as did the corticospinal tract in the posterior internal capsule..  

Neuroradiologic superposition of cerebral lesions detected by computed tomography (CT) or magnetic resonance imaging (MRI) showed that nearly all patients who perceived their scotomata had lesions involving the primary visual cortex or the perigeniculate region, whereas those who received no scotoma had lesions centered within the optic radiation.  

Following severe cranio-cerebral trauma that affected the optic radiation, patient FS suffers from an incomplete macula-splitting hemianopia.  

At 37 weeks an initiation of myelination in the optic radiation has been demonstrated in post-mortem studies.  

This loss was related neither to inadvertent injury of cortical areas neighboring MT nor to incidental optic radiation damage.  

Expression of PLP was first detected in the pallidothalamic fibers and globus pallidus at 20 weeks; it then extended to the striatum at 28 weeks, pericentral gyri and optic radiation at 35 weeks, and acoustic radiation at 40 weeks.  

This unusual form of optic nerve hypoplasia most likely results from transsynaptic degeneration of optic axons caused by the primary bilateral lesion in the optic radiation..  

A general delay in the myelination-particularly in the myelination of the optic radiation-was a common finding and until now has not been described in children with CVI routinely.  

In the LGN and LIP, double-stained neurons were scarce, but in the fibre capsule of these nuclei, as well as in the optic radiation (OR) and white matter underlying area 17, both double-stained PV + CR or CR + CB and separate populations of PV-ir, CB-ir and CR-ir neurons and fibres were observed.  

RESULTS: Nonparametric analysis of variance showed that T1 decreases with age in the genu, frontal white matter, caudate, putamen, anterior thalamus, pulvinar nucleus, optic radiation, cortical gray matter (all P < .0001), and occipital white matter.  

Other venous convergences such as those related to the optic radiation in the para-atrial area were also found.  

Four patients had medial occipital lesions that spared the putative motion area in lateral occipitotemporal cortex and the optic radiations proximal to this site. The other six had lesions involving this area or the proximal optic radiations.  

Magnetic resonance imaging disclosed a rare form of hemimegalencephaly characterized by hypoplasia of an optic radiation within the enlarged, dysgenetic cerebral hemisphere. CONCLUSION: The spectrum of oculocerebral dysgenesis in the linear nevus sebaceous syndrome can be expanded to include peripapillary staphyloma and atypical hemimegalencephaly with hypoplasia of an optic radiation..  

Five patients had medial occipital lesions that spared the putative motion area in lateral occipitotemporal cortex and the optic radiations and other white matter tracts proximal to this site. The other 5 had lesions involving this area or the proximal optic radiations. No patient in either group discriminated motion direction in signal/noise RDCs at a level better than chance, and the performance of those with lesions restricted to medial occipital lobe did not differ from those with lateral occipital or optic radiation lesions.  

Least-squares regression analysis shows that T1 varied as a function of age in pulvinar nucleus (R2 = 56%), anterior thalamus (R2 = 51%), caudate (R2 = 50%), frontal white matter (R2 = 47%), optic radiation (R2 = 39%), putamen (R2 = 36%), genu (R2 = 22%), occipital white matter (R2 = 20%) (all p < 0.0001), and cortical gray matter (R2 = 53%) (p < 0.001).  

Although high intensity lesions were observed in the right occipital and temporal lobes, especially around the optic radiation, on T2-weighted brain MRI before the start of intrathecal interferon-alpha (IFN-alpha) therapy, they had disappeared at about two months after the treatment.  

RESULTS: In the optic radiation, diffusional anisotropy was observed in neonates < 1 month old, whereas signal intensity became high after 1 month old.  

The distribution of neurons and fibers immunoreactive (ir) to the three calcium-binding proteins parvalbumin (PV), calbindin D-28k (CB), and calretinin (CR) was studied in the human lateral geniculate nucleus (LGN), lateral inferior pulvinar, and optic radiation, and related to that in the visual cortex. In the optic radiation both PV- and CR-immunoreactive neurons, puncta, and fibers were present. There were hardly any CB-ir puncta or fibers in the laminae, interlaminar zones, geniculate capsule, or optic radiation.  

The severity of ventricular dilatation, the degree and extent of white matter reduction, optic radiation involvement, and the thinning of the posterior corpus callosum correlated significantly with the Full Scale and Performance IQ: no correlation was observed between the Verbal IQ and any of the MRI features analyzed.  

PURPOSE: To determine whether a hyperintense layer adjacent to the lateral ventricle on T2-weighted MR images represents the optic radiation. The MR images in a patient with cerebral infarction involving the lateral geniculate body were also reviewed to evaluate wallerian degeneration of the optic radiation. RESULTS: The external sagittal stratum, composed of the optic radiation, showed a pale layer in specimens stained by Bodian's method. CONCLUSIONS: The hyperintense layer on T2-weighted images represents the external sagittal stratum, or optic radiation.  

Myelination of the pons, cerebellum, thalamus, internal capsules, optic radiation, centrum semiovale and cerebral white matter was separately assessed.  

T2-weighted MRI showed a high signal intensity lesion in the occipital white matter along the optic radiation.  

In the lateral geniculate nucleus, senile plaques were encountered more often in parvocellular than in magnocellular layers, in the interlaminar zones, in the optic radiation and in the adjacent pre-geniculate nucleus.  

Lesions of these patients were concentrated along the optic radiation and spared the primary visual cortex.  

The response steadily increased in amplitude through the optic radiation, lamina A and lamina A1.  

Both foveal and peripheral phosphenes had identical stimulation depths, implying a subcortical stimulation site, possibly in the optic radiation fibers adjacent to the posterior tip of the lateral ventricles.  

In MRI of postmortem brain, T1WI and T 2WI was able to clearly show the myelination process of brainstem, basal ganglia, internal capsule and optic radiation in a 2 months-old-boy.  

The results indicate that in both types of migraine there is a common underlying pathogenetic mechanism and the affected retrochiasmatic optic radiation has an increased response to sensory input modulation..  

Homonymous visual field defects are rare in patients with MS and are usually caused by large lesions in the white matter of the posterior optic radiations and visual cortex. The postulate of Holmes and others, early this century, that optic radiation lesions could produce quadrantic defects has recently been questioned.  

The advantages of this method are clear orientation to the mesial temporal structures, easy access to the posteromesial part of the temporal lobe, and preservation of functionally important structures, such as the lateral temporal speech area, optic radiation, and temporal stem.  

On MRI, both patients exhibited diffuse involvement of the cerebral white matter, excluding the internal capsule and optic radiation.  

MRI revealed that myelinated fibers were localized in brainstem, cerebellum, internal capsule, optic radiation and proximal corona radiata in case 1, while myelinated fibers were almost absent in case 2-4.  

Stimulation of the mesencephalic reticular formation facilitates responses in the visual cortex elicited from the optic radiation.  

Follow up MRI 15 months after onset of CVI in one patient showed marked atrophy of the occipital cortex, hyperintensities of the cortical white matter and no visible optic radiation.  

Thirty Sprague-Dawley rats were exposed to optic radiation of 404 nm with a retinal dose of 110kJ/m2.  

Myelination of the centrum semiovale and optic radiation could be seen in T1WI in the newborn up to 3 months old, and in T2WI at 3-5 months old.  

The corpus geniculatum laterale and the retrogeniculate optic radiation had a normal appearance on MRI in all patients. Therefore we conclude that normal myelination of the optic radiation, as it can be grossly assessed by MRI, can take place even with absent or greatly reduced visual sensory input..  

MRI allows a detailed anatomical assessment and an evaluation of the myelination, including the optic radiation. In children with Leber congenital retinal amaurosis we have observed a normal myelination of the optic radiation.  

In the circumscribed, long-standing, clinically absolute visual field defects of three patients with vascular lesions that involved the optic radiation and visual cortex, forced-choice discrimination between coloured stimuli was tested.  

Magnetic resonance imaging revealed asymptomatic lesions in white matter regions corresponding with the optic radiations in 20 of 28 patients (71%) with clinically isolated optic neuritis.  

Then myelination is observed in the striatum, and precentral and postcentral gyri at 35 weeks, and the anterior internal capsule and optic radiation at 37 weeks.  

optic radiation induced as a result of mechanic activation of venous blood in a TPA-2 triboluminometer, was measured in patients with cancer of the gastric cardia and esophagus, and in healthy subjects.  

Extracellular field potential recording to electrical stimulation of the optic radiation was performed in slices of cerebral cortex maintained in vitro.  

The electromagnetic spectrum is subdivided into individual sections and includes: Static and low-frequency electric and magnetic fields including technical applications of energy with mains frequency, radio frequency fields, microwaves and optic radiation (infrared, visible light, ultraviolet radiation including laser).  

Myelination was graded in two specified sites, optic radiation and corpus callosum, based on the stages of normal term babies and healthy premature infants.  

The first child had hydrocephalus with an enhancing mass at the hypothalamus which followed the optic radiation to include the lateral geniculate body and medial temporal lobe.  

The suppression of spontaneous activity was accompanied by a reduction of the antidromic excitability, assessed by stimulating LGN axons within the cortex or optic radiation.  

Associated fibers: superior occipito-frontal fasciculus, superior longitudinal fasciculus, ucinate fasciculus, cingulum bundle, optic radiation fornix and mammillothalamic tract..  

Cerebral lesions confined to the internal capsule, cerebral peduncle and optic radiation in the adult onset ALD including AMN and symptomatic heterozygote, have not been reported and this confinement may indicate an early stage of the disease..  

A three-dimensional, computer-aided reconstruction of the intracranial parts of the visual system, optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiation and striate area on the basis of anatomical serial cuts is presented in this paper.  

Up to now little involvement of the afferent visual pathway (optic nerve and optic radiation and visual cortex) in HIV infection has been apparent.  

Such observations could be accounted for by divergence in the optic radiation. To explore the hypothesis of fibre divergence, we made small knife cuts in the distal optic radiation of macaca fascicularis.  

The fiber arrangement of the optic radiation was investigated in fourteen adult cats.  

Except for the optic radiation and the corpus callosum which was remarkably modified, the optic tract, chiasm, nerve and retina were morphologically and histologically normal.  

Hypoperfusion in the cerebellar hemisphere contralateral to supratentorial lesions, the overlying cerebral cortex ipsilateral to subcortical lesions, the thalamus ipsilateral to cortical lesions, and the visual cortex distant to optic radiation lesions was demonstrated using SPECT with 123I-IMP.  

SPECT demonstrated a reduction in blood flow in the cerebellar hemisphere contralateral to the cerebral infarct, the cortex ipsilateral to the subcortical infarct, the visual cortex distal to the optic radiation lesion, and the thalamus ipsilateral to the cortical infarct.  

The most prominent difference with respect to quadrantanopsias resulting from lesions of the optic radiation is the high degree of congruity, especially in the central portion of the field.  

Two categories of fibres are present in the white matter of the temporal lobe: projection fibres (acoustic radiation, optic radiation, temporo-pontine tract, temporo-thalamic fasciculus) and association fibres (cingulum, anterior longitudinal, uncinate, superior occipitofrontal, superior longitudinal fasciculi).  

T2 time constants were measured within the caudate nucleus, putamen, globus pallidus, cortical gray matter, subcortical white matter, and optic radiation.  

Discharge evoked by optic radiation stimulation was facilitated by conditioning stimulation (6 pulses over 24 msec) of the locus coeruleus (LC), whereas no consistent effect was exerted on resting discharge.  

Optic fibers then spread across the chiasm, the nasal quadrant splits, taking up positions in the rostral and caudal margins of the optic radiation.  

Degeneration of the optic radiation, posterior half of the corpus callosum, thalamus, cerebellar white matter, and gracile tract in high cervical segments were also observed.  

Increased signals from the optic chiasm to optic radiation were found in 5 cases.  

Hemianopsia of vascular origin can be caused by diseases in the carotid circulation (optic tract, proximal third of the optic radiation), as well as in the vertebrobasilar arterial system (middle and distal thirds of the optic tract, striate area/calcarina).  

In homonymous defects, consideration of further simple anatomic features of the visual pathway, namely the knee of Wilbrand and that portion of the optic radiation which extends anteriorly to the temporal lobes and which represents the inferior retinal halves with characteristic defects, also enables lesions in the visual pathway to be localized more accurately..  

Homonymous hemianopsia may be caused by tumors in the region of the optic tract, the lateral geniculate body, the optic radiation, and the visual cortex.  

Damage to the optic radiation during surgery in the temporal lobe results in more or less severe visual field defects. In the present study, the optic radiation was represented by either Klingler's fibre dissection technique or by consecutive frontal sections respectively in 25 formalin-fixed human hemispheres.  

Latencies were long compared to those obtained after stimulation of the optic radiation.  

Finally, latencies to electrical stimulation of the optic chiasm or the optic radiation were significantly longer in strabismic cats.  

The plaques were periventricular or in the optic radiation.  

Here we use intracellular recording techniques to show that LTP can be induced by high frequency stimulation of the optic radiation in slices of the visual cortex of adult rats.  

Auditory pathway disease was characterized as involvement of the lateral lemniscus and medial geniculate body, and visual pathway disease was characterized by lateral geniculate body, Meyer loop, and optic radiation involvement.  

the optic radiation), the cranial extension of the posterior cerebral infarctions and the splenial as well as thalamic lesions.  

In the visual cortex the loss of the r1 response reveals more clearly than is normally possible an r2 response, the response of the X optic radiation fibres.  

Abnormal signal, probably signifying tumor spread into the optic radiation, was detected on T2-weighted images in one case.  

Midsagittal inversion recovery (IR) images demonstrated that the corpus callosum was completely intact, and coronal IR images revealed involvement of the lingual gyrus, fusiform gyrus, forceps major, inferior longitudinal fascicle, and optic radiation in the dominant cerebral hemisphere in both cases.  

Pairs of injections of different neuroanatomical tracers--peroxidase-conjugated wheat-germ agglutinin (WGA) and [ 3H]proline--were made into the lateral geniculate nucleus (LGN) of the cat, and the course of the labeled fibers in the optic radiation was reconstructed. When the two injections were widely separated in the rostrocaudal dimension of the LGN (i.e., one in the representation of the lower quadrant of the visual field and one in the upper quadrant), the two sets of labeled fibers also remained separated in the long (roughly rostrocaudal) axis of the optic radiation. This crossing is the basis of the topological inversion in the optic radiation deduced previously by Connolly and Van Essen (J. The WGA injections also labeled the corticogeniculate fibers by retrograde transport; these fibers traveled in a separate pathway medial to the optic radiation..  

and the optic radiation, not from the optic tract, superior colliculus or other surrounding structures.  

There is a normal mediolateral gradient of cell sizes and some signs of a laminar differentiation, cells next to the optic tract being morphologically distinguishable from cells near the optic radiation, but no cell-free interlaminar zones are formed.  

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