Chapter 3. Visual Pathways from Eye to Brain

3.1 Title slide

Demonstration 3.1
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Visual Pathways from Eye to Brain

Show how neural signals flow along the visual pathways in response to light from the left and right visual fields.

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This fMRI image shows activation in the left visual cortex in response to viewing a stimulus in the right visual field, illustrating the contralateral representation of visual space. [Image from Dougherty et al., 2003]

What Are the Visual Pathways from the Eyes to the Brain?

Light from the left half of the visual field strikes the right half of each retina, while light from the right half of the visual field strikes the left half of each retina. Within each retina, this light is transduced into neural signals in the 1 million axons of the retinal ganglion cells (RGCs) that emerge from the back of each eye to form the optic nerve.

The left and right optic nerves travel only a few centimeters until they meet at the optic chiasm, where the optic nerve from each eye splits in half. The axons from the RGCs in the right half of the right retina and the right half of the left retina (i.e., from the right temporal retina and the left nasal retina) combine into the right optic tract, which continues into the right hemisphere of the brain. The axons from the RGCs in the left half of the right retina and the left half of the left retina (i.e., from the left temporal retina and the right nasal retina) combine into the left optic tract, which continues into the left hemisphere.

Thus, as a consequence of the splitting of the optic nerves and their recombining into the optic tracts, neural signals carrying information from the left visual field go to the right hemisphere of the brain, while signals carrying information from the right visual field go to the left hemisphere. This is referred to as the contralateral representation of visual space.

Within each hemisphere, about 90% of the axons in the optic tract go to the lateral geniculate nucleus, which sends signals to the primary visual cortex (area V1) via the optic radiations; most of the other axons in the optic tract branch off to the superior colliculus.

3.2 Explain

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Click on the left and right visual fields to see how light rays produce neural signals that flow along the visual pathways into the right and left hemispheres of the brain.

VISUAL FIELD

Left
Right
Left temporal retina
Left nasal retina
Optic nerve
Optic chiasm
Optic tract
Lateral geniculate nucleus
Superior colliculus
Optic radiations
Primary visual cortex (area V1)
Right temporal retina
Right nasal retina

3.3 Explain - dnd

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Drag and drop each label into the correct box on this cross section of the eyes and brain viewed from above.

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Optic nerve
Optic tract
Left nasal retina
Optic chiasm
Superior colliculus
Lateral geniculate nucleus
Right nasal retina
Left temporal retina
Primary visual cortex (area V1)
Right temporal retina
Optic radiations

3.4 Explain

explain_text

What Are the Visual Pathways from the Eyes to the Brain?

Light from the left half of the visual field strikes the right half of each retina, while light from the right half of the visual field strikes the left half of each retina. Within each retina, this light is transduced into neural signals in the 1 million axons of the retinal ganglion cells (RGCs) that emerge from the back of each eye to form the optic nerve.

The left and right optic nerves travel only a few centimeters until they meet at the optic chiasm, where the optic nerve from each eye splits in half. The axons from the RGCs in the right half of the right retina and the right half of the left retina (i.e., from the right temporal retina and the left nasal retina) combine into the right optic tract, which continues into the right hemisphere of the brain. The axons from the RGCs in the left half of the right retina and the left half of the left retina (i.e., from the left temporal retina and the right nasal retina) combine into the left optic tract, which continues into the left hemisphere.

Thus, as a consequence of the splitting of the optic nerves and their recombining into the optic tracts, neural signals carrying information from the left visual field go to the right hemisphere of the brain, while signals carrying information from the right visual field go to the left hemisphere. This is referred to as the contralateral representation of visual space.

Within each hemisphere, about 90% of the axons in the optic tract go to the lateral geniculate nucleus, which sends signals to the primary visual cortex (area V1) via the optic radiations; most of the other axons in the optic tract branch off to the superior colliculus.

3.5 Test - dnd

You must complete the question and then click SUBMIT before you can click proceed to the next screen.
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Question

91DZbqs/DL4suRuMSS5x3Z9uZpSnIONWDBFZt9VOuww=
Slide 5/Test Yourself 1 Matching Activity

Fill the empty boxes by dragging and dropping the correct answers. Then click SUBMIT.

Light rays from the left visual field strike

Light rays from the right visual field strike

the left nasal retina and the left temporal retina.

the left nasal retina and the right temporal retina.

the right nasal retina and the left temporal retina.

the right nasal retina and the right temporal retina.

3.6 Test - single choice

You must select an answer and then click SUBMIT before you can click proceed to the next screen.
test_single_choice

Select your answer to the question below. Then click SUBMIT.

Question

4GjVl8pI5nZ3wvRICvxm/yrU508EsVMWjuApAR9F0pUjY59lOEjYzxjtGV8jB2m3Z5nOlf3gibCXSdyYqRhHAAUInAtv4yDpFdyrWkb9ba2veb46Fw78aYXHaYdjExUBPw+ymYQ4VupbzrrH/HXB7dC4epjdDhTTbf15njKpjFYJqLTevwJAWYACngYgD/PSsAXQmZODCoPglKi1H/ktAgs8wQsFeCXtANPkRQ5AKL404DzUGGPb6XCWOCwK2Q7cdfnPymAznURAs2SNmui0QcQll0k04zB5+nMLgcYCHPZ3eVgWBuTLSRtgYAGXGUH4qFVXw/hXFc+QMgYNrXx7Mic7nDIiVkUFp3g/66EN/fYd2y/HjDi/2PE1RXAvgScDX+gQCyVxlobxv4F3zs2b2ykrNKbUs+SSGDTiZM7/euebMCGRF2jFoFFs4uYMfDPIKzZV8CzrVt5JqDjHGjGT57Up+CSFXvOUDgkEuoGTq2GJtxbnTqaa5M8ihwIq5q+8w/uH5+kLEEV1Pa7BaNKTrsCH6i8wGNoXt8VQ6V090uY2ezOzORtmk6bNRS5zLGl2QKmfkV+0q9xtnRB6MzBdHB21DMx/8u/3JEYzx2b3AenQQEGdgZXNv9xMJAxXPmlpX12BYB1BQ3Ro+S9IsQqh6/vFv67Jmo3Y1viS5GotKwgf7H/pJwGRL6Pg/RDcGPOKvh6h788d8DqMkOItzlTAnPjc4TACatWtxORG2E62LTUHFcn5EaTi4KDBy5bBqSBGdxUjJNgNjPUWkBmN1w0TAyn7q6vmrnB9BS0o3tD/xh4689yiAkOuhVw0Tuw=
Correct! Click EXPLAIN if you want to review this topic.
Incorrect. The correct answer is B. Click EXPLAIN if you want to review this topic.

3.7 Test - single choice

You must complete the question and then click SUBMIT before you can click proceed to the next screen.

Click on the image that best illustrates what is meant by the contralateral representation of visual space. Then click SUBMIT.

Question

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
Correct!
Incorrect.
The correct answer is B.

3.8 Activity completed

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