Visual pathways

2012 ◽  
Author(s):  
Christopher Kennard ◽  
Sara Ajina
Keyword(s):  
Visual Processing ◽  
Optic Tract ◽  
Occipital Lobe ◽  
Optic Chiasm ◽  
Visual Disturbance ◽  
Visual Pathways ◽  
Ophthalmological Examination ◽  
Anatomy And Physiology ◽  
The Brain ◽  
Visual Disturbances

Visual disturbances may be caused by diseases of the optic disc, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiations, and occipital lobe of the brain, as well as other brain areas involved in complex visual processing.Diagnosis of disturbances of the visual pathways requires both knowledge of their anatomy and physiology, and the ability to carry out a thorough neuro-ophthalmological examination which should enable (1) documentation of the character and extent of the visual disturbance, and (2) topographic localization of the lesion, so that the relevant investigative techniques, such as radiological imaging, can be appropriately requested....

Visual pathways

2020 ◽  
pp. 5913-5922
Author(s):  
Sara Ajina ◽  
Christopher Kennard
Keyword(s):  
Visual Processing ◽  
Optic Tract ◽  
Occipital Lobe ◽  
Optic Chiasm ◽  
Visual Disturbance ◽  
Visual Pathways ◽  
Ophthalmological Examination ◽  
Anatomy And Physiology ◽  
Investigative Techniques ◽  
The Brain

This chapter investigates visual disturbances, which may be caused by diseases of the optic disc, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiations, and occipital lobe of the brain, as well as other brain areas involved in complex visual processing. Diagnosis of disturbances of the visual pathways requires both knowledge of their anatomy and physiology, and the ability to carry out a thorough neuro-ophthalmological examination which should enable (1) documentation of the character and extent of the visual disturbance, and (2) topographic localization of the lesion, so that the relevant investigative techniques, such as radiological imaging, can be appropriately requested.

Visual pathways

2010 ◽  
pp. 4851-4857
Author(s):  
Christopher Kennard ◽  
Sara Ajina
Keyword(s):  
Visual Processing ◽  
Optic Tract ◽  
Occipital Lobe ◽  
Optic Chiasm ◽  
Visual Disturbance ◽  
Visual Pathways ◽  
Ophthalmological Examination ◽  
Anatomy And Physiology ◽  
Investigative Techniques ◽  
The Brain

Visual disturbances may be caused by diseases of the optic disc, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiations, and occipital lobe of the brain, as well as other brain areas involved in complex visual processing. Diagnosis of disturbances of the visual pathways requires both knowledge of their anatomy and physiology, and the ability to carry out a thorough neuro-ophthalmological examination which should enable (1) documentation of the character and extent of the visual disturbance, and (2) topographic localization of the lesion, so that the relevant investigative techniques, such as radiological imaging, can be appropriately requested....

The Optic Chiasm of Australian Marsupials

1995 ◽  
Vol 43 (5) ◽  
pp. 467
Author(s):  
AM Harman
Keyword(s):  
Nervous System ◽  
Optic Nerve ◽  
Central Region ◽  
Optic Tract ◽  
Optic Chiasm ◽  
Lateral Part ◽  
Guidance Cues ◽  
Optic Axons ◽  
The Brain

The optic chiasm of mammals is the region of the nervous system in which optic axons have a choice of route, either they enter the optic tract on the same side of the brain or they cross the chiasm and enter the opposite optic tract. in eutherian (placental) mammals, axons approach the midline of the chiasm and then either continue across the chiasm or turn back to enter the tract on the same side of the brain. The midline of the chiasm provides guidance cues that repel uncrossed but not crossed axons. However, it has recently been shown that in a marsupial, the quokka wallaby, axons destined to stay on the same side of the brain remain in the lateral part of the optic nerve and chiasm and never approach the midline. The structure of the chiasm reflects this partitioning of axons with different routes by having a tripartite structure. The two lateral regions contain only uncrossed axons in rostral chiasmatic regions and the central region contains only crossed axons. Therefore, axons passing through the chiasm of this species must use guidance cues that differ from those of eutherian mammals. Here I show that the chiasms of species of both diprotodont and polyprotodont Australian marsupials have a similar tripartite structure and that uncrossed axons are confined to lateral regions. It seems likely, therefore, that the chiasm of marsupials has fundamental differences in structure and optic axon trajectory compared with that of eutherian mammals studied to date.

scholarly journals Visual Disturbance Caused by a Nail Gun-Induced Penetrating Brain Injury

2021 ◽  
Vol 34 (3) ◽  
pp. 203-207
Author(s):  
Jin Bong Ye ◽  
Young Hoon Sul ◽  
Se Heon Kim ◽  
Jin Young Lee ◽  
Jin Suk Lee ◽  
...  
Keyword(s):  
Brain Injury ◽  
Parietal Lobe ◽  
Superior Sagittal Sinus ◽  
Occipital Lobe ◽  
Visual Disturbance ◽  
Neurological Deficits ◽  
Penetrating Brain Injury ◽  
Sagittal Sinus ◽  
Neurologically Intact ◽  
The Brain

Penetrating brain injury caused by a nail gun is an uncommon clinical scenario reported in the literature. A 36-year-old male presented with a nail that had penetrated through the occipital bone. He was alert and neurologically intact except for visual disturbance. Computed tomography (CT) of the brain showed the nail lodged at the occipital lobe and the parietal lobe, with minimal intracerebral hemorrhage. The nail was placed in the occipital lobe close to the superior sagittal sinus. We removed the nail with craniotomy since the entrance of the nail was close to the superior sagittal sinus. There were no newly developed neurological deficits postoperatively. Immediate postoperative CT showed no newly developed lesions. The patient recovered well without any significant complications. Two weeks postoperatively, magnetic resonance imaging showed no remarkable lesions. The visual disturbance was followed up at the outpatient department. To summarize, we report a rare case of penetrating head injury by a nail gun and discuss relevant aspects of the clinical management.

scholarly journals Regression after subtotal resection of an optic pathway glioma in an adult without adjuvant therapy: case report

2019 ◽  
Vol 130 (6) ◽  
pp. 2005-2008
Author(s):  
Eveline Teresa Hidalgo ◽  
Michelle W. McQuinn ◽  
Jeffrey H. Wisoff
Keyword(s):  
Adjuvant Therapy ◽  
Optic Tract ◽  
Optic Chiasm ◽  
Optic Pathway Glioma ◽  
Subtotal Resection ◽  
Optic Pathway ◽  
Ophthalmological Examination ◽  
Homonymous Hemianopsia ◽  
Juvenile Pilocytic Astrocytoma ◽  
Personality Changes

Optic pathway gliomas (OPGs) are relatively common and benign lesions in children; however, in adults these lesions are nearly always malignant and hold a very poor prognosis. In this report the authors present the case of an adult patient with a benign OPG who underwent subtotal resection without adjuvant therapy and has had no tumor progression for more than 20 years. A 50-year-old woman presented with a 2-year history of personality changes, weight gain, and a few months of visual disturbances. Ophthalmological evaluation showed incomplete right homonymous hemianopsia. MRI demonstrated a 2.5 × 2.5 × 2.5–cm enhancing left-sided lesion involving the hypothalamus with extension into the suprasellar cistern, extending along the left optic tract and anterior to the level of the optic chiasm. A biopsy procedure revealed a juvenile pilocytic astrocytoma. A subtotal resection of approximately 80% of the tumor was performed. Postoperatively, the patient experienced complete resolution of her personality changes, and her weight decreased back to baseline. Ophthalmological examination showed increased right homonymous hemianopsia. In the years following her surgery, there was a spontaneous decrease in tumor size without adjuvant therapy. The patient continues to have an excellent quality of life despite a visual field defect, and no further tumor growth has been observed.

scholarly journals Anatomic study of the arterial vascularization of the brain base of paca (Cuniculus paca)

2020 ◽  
Vol 40 (9) ◽  
pp. 733-737
Author(s):  
Tais H.C. Sasahara ◽  
Vitória F.N.P. Fontes ◽  
Débora O. Garcia ◽  
Daniel W. Rocha ◽  
Fabrício S. Oliveira ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Basilar Artery ◽  
Cerebral Arteries ◽  
Optic Tract ◽  
Optic Chiasm ◽  
Arterial System ◽  
Medial Branch ◽  
Vertebrobasilar System ◽  
The Right ◽  
The Brain

ABSTRACT: Paca (Cuniculus paca Linnaeus, 1766), rodent belong to the Cuniculidae family, has encouraged numerous scientific researches and for this reason could be an experimental model in both human and veterinary areas. And recently, the economic exploitation of the meat cuts, has being direct implication in its zootechnical importance. However, no anatomical descriptions regarding the vascularization of the base of the brain in this rodent has being found. Thus, the aim of the present study was to describe the arteries and the pattern of the vasculature and to compare it with the other species already established in the literature. For this, five pacas, donated by the Unesp Jaboticabal Wildlife Sector, were euthanized followed by the vascular arterial system was injected with red-stained-centrifuged latex by the common carotid artery. After craniectomy, the brains were removed and the arteries were identified and, in addition, compared with those described in other animal species. The presence of the right and left vertebral arteries, close to the medulla oblongata, was detected, originating the basilar artery, which divided into the terminal branches of the right and left basilar artery. Ventral to the optic tract there was the right internal carotid artery and the left, dividing the middle cerebral artery and left rostral and right; dorsal to the optic chiasm, the medial branch of the rostral cerebral arteries was identified. Based on the results, it is concluded that the vascularization of the paca brain base is supplied by the carotid and vertebrobasilar system.

Amacrine cell-mediated input to bipolar cells: Variations on a common mechanistic theme

2012 ◽  
Vol 29 (1) ◽  
pp. 41-49 ◽  
Author(s):  
WILLIAM N. GRIMES
Keyword(s):  
Visual Processing ◽  
Amacrine Cell ◽  
Ganglion Cells ◽  
Amacrine Cells ◽  
Negative Influence ◽  
Bipolar Cells ◽  
Single Class ◽  
Anatomy And Physiology ◽  
Functional Context ◽  
The Brain

AbstractFeedback is a ubiquitous feature of neural circuits in the mammalian central nervous system (CNS). Analogous to pure electronic circuits, neuronal feedback provides either a positive or negative influence on the output of upstream components/neurons. Although the particulars (i.e., connectivity, physiological encoding/processing/signaling) of circuits in higher areas of the brain are often unclear, the inner retina proves an excellent model for studying both the anatomy and physiology of feedback circuits within the functional context of visual processing. Inner retinal feedback to bipolar cells is almost entirely mediated by a single class of interneurons, the amacrine cells. Although this might sound like a simple circuit arrangement with an equally simple function, anatomical, molecular, and functional evidence suggest that amacrine cells represent an extremely diverse class of CNS interneurons that contribute to a variety of retinal processes. In this review, I classify the amacrine cells according to their anatomical output synapses and target cell(s) (i.e., bipolar cells, ganglion cells, and/or amacrine cells) and discuss specifically our current understandings of amacrine cell-mediated feedback and output to bipolar cells on the synaptic, cellular, and circuit levels, while drawing connections to visual processing.

scholarly journals Blindsight.

2021 ◽  
Author(s):  
James Danckert ◽  
Christopher Lee Striemer ◽  
Yves Rossetti
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Spatial Localization ◽  
Visual Pathways ◽  
Motion Processing ◽  
Functional Characteristics ◽  
The Brain

For over a century research has demonstrated that damage to primary visual cortex does not eliminate all capacity for visual processing in the brain. From Riddoch’s (1917) early demonstration of intact motion processing for blind field stimuli, to the iconic work of Weiskrantz and colleagues (1974) showing reliable spatial localization, it is clear that secondary visual pathways that bypass V1 carry information to the visual brain that in turn influences behavior. In this chapter we briefly outline the history and phenomena associated with blindsight, before discussing the nature of the secondary visual pathways that support residual visual processing in the absence of V1. We finish with some speculation as to the functional characteristics of these secondary pathways.

Penetration of the optic chiasm by a ruptured anterior communicating artery aneurysm

1997 ◽  
Vol 87 (2) ◽  
pp. 324-326 ◽  
Author(s):  
Isao Date ◽  
Tatsuro Akioka ◽  
akashi Ohmoto
Keyword(s):  
Optic Tract ◽  
Artery Aneurysm ◽  
Optic Chiasm ◽  
Visual Disturbance ◽  
Abrupt Onset ◽  
Anterior Communicating Artery ◽  
Content Type ◽  
Anterior Communicating Artery Aneurysm ◽  
Finger Counting ◽  
The Right

✓ There are few reports of anterior communicating artery aneurysms causing visual symptoms, and penetration of the optic chiasm by such aneurysms has not been reported. A 40-year-old man presented with the abrupt onset of left homonymous hemianopsia, right visual acuity disturbance (finger counting), and slight headache. Angiography disclosed a 7-mm anterior communicating artery aneurysm projecting inferiorly. After the neck of the aneurysm was clipped, the dome of the aneurysm was resected. The operation confirmed that the aneurysm had penetrated the right half of the optic chiasm and the thrombosed dome had also compressed the right optic tract. Although the aneurysm was successfully clipped, the visual disturbance persisted after surgery, suggesting that the damage to the visual pathways by aneurysm penetration was irreversible in this case.

Abnormal vision

2011 ◽  
Author(s):  
Christopher Kennard
Keyword(s):  
Differential Diagnosis ◽  
Motor System ◽  
General Medicine ◽  
Final Diagnosis ◽  
Visual Pathways ◽  
Ophthalmological Examination ◽  
Ocular Motor ◽  
Anatomy And Physiology ◽  
Ocular Motor System

Neuro-ophthalmology is a discipline comprising a wide variety of disorders that overlap the fields of neurology, ophthalmology and general medicine. Diagnosis in this field requires a thorough knowledge of the anatomy and physiology of the visual pathways and ocular motor system, as well as the ability to carry out a thorough neuro-ophthalmological examination. The combination of the history and any abnormalities identified by the examination should enable a detailed differential diagnosis to be reached, leading to appropriate investigations if required, and a final diagnosis.

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