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The visual pathway consists of structures that carry visual information from the retina to the brain.Lesions in that pathway cause a variety of visual field defects. In the visual system of human eye, the visual information processed by retinal photoreceptor cells travel in the following way:
Foster Kennedy syndrome is a constellation of findings associated with tumors of the frontal lobe. [1]Although Foster Kennedy syndrome is sometimes called "Kennedy syndrome", [2] it should not be confused with Kennedy disease, or spinal and bulbar muscular atrophy, which is named after William R. Kennedy.
Visual fields tests will delineate chiasmal syndromes because the missing fields will not cross the midline. Junctional scotomas classically show ipsilateral optic disc neuropathy with contralateral superotemporal defects. Bitemporal hemianopia with or without central scotoma is present if the lesions have affected the body of the chiasm. A ...
Lesions in the optic tract correspond to visual field loss on the left or right half of the vertical midline, also known as homonymous hemianopsia. A lesion in the left optic tract will cause right-sided homonymous hemianopsia, while a lesion in the right optic tract will cause left-sided homonymous hemianopsia.
If a lesion only exists in one unilateral division of the optic radiation, the consequence is called quadrantanopia, which implies that only the respective superior or inferior quadrant of the visual field is affected. If both divisions on one side of the brain are affected, the result is a contralateral homonymous hemianopsia.
Many brain structures that are responsive to visual input, including much of the visual cortex and visual nuclei of the brain stem (such as the superior colliculus) and thalamus (such as the lateral geniculate nucleus and the pulvinar), are organized into retinotopic maps, also called visual field maps. Areas of the visual cortex are sometimes ...
Bitemporal hemianopsia is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland.
It creates a bottom-up saliency map of the visual field to guide attention or eye gaze to salient visual locations. [35] [clarification needed] Hence selection of visual input information by attention starts at V1 [36] along the visual pathway. Visual information then flows through a cortical hierarchy. These areas include V2, V3, V4 and area ...
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