What are the steps in the visual pathway in human vision?

What are the steps in the visual pathway in human vision?

Introduction

• When light passes through the lens it reaches the. the retina, where the formed image is.
• Summary of conscious vision perception. retina → optic nerve → optic chiasm → optic tract → lateral geniculate body → optic radiation to primary visual cortex.
• Additional pathways.

What does a lesion on the optic nerve mean?

Because most fibres in the optic nerve subserve macular vision, lesions within the nerve disproportionately affect central vision and colour vision. A total optic nerve lesion causes unilateral blindness with loss of pupillary light reflex.

What causes lesions on the optic nerve?

Bacterial infections, including Lyme disease, cat-scratch fever and syphilis, or viruses, such as measles, mumps and herpes, can cause optic neuritis. Other diseases. Diseases such as sarcoidosis, Behcet’s disease and lupus can cause recurrent optic neuritis. Drugs and toxins.

What effects would a lesion have on the right optic nerve?

A lesion of the right optic nerve causes a total loss of vision in the right eye; it also produces a right afferent pupil deficit.

How many visual pathways are there?

In addition to the primary visual pathways, two other major visual pathways can be distinguished: the tectal, or collicular, pathway and the pretectal nuclei pathway. Thus fibers from the optic tracts do not all go to the lateral geniculate body.

What happens if there is a lesion in the left optic tract?

A lesion in one optic tract, interrupting all fibers carrying information from the contralateral visual fields, may cause homonymous hemianopia. When an injury to the left optic tract occurs, the patient will have visual difficulties (visual field cuts) in the right eye’s inner field, but in the left eye’s outer field.

What happens if the dorsal visual pathway is damaged?

Dorsal damage can cause: Trouble with spatial perception and perception of complex movement. Trouble with spatial orientation and navigation. Impaired spatial guidance of motor activities (saccadic and pursuit eye movements; reaching, grasping and pointing; walking over steps; navigating crowds and obstacles)

What happens when the ventral pathway is damaged?

Ventral damage can cause: Impairments in contrast sensitivity, form and color vision, and depth perception. Impairments in object and face perception and route-finding.

What happens if the ventral visual pathway is damaged?

What are the two visual pathways in the brain?

Beyond area V1 (shown at occipital pole) and V2 of the cortex, the visual pathway is segregated into two separate pathways—dorsal (red arrows) and ventral (green arrows).