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Week 9 Flashcards

(52 cards)

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1
Q

Retinofugal projection definition

A

the neural pathway that carries visual information from the retina to the brain, primarily through the optic nerve, optic chiasm, and optic tract

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2
Q

Optic nerve definition:

A

axon so that visual information can be sent to the rest of the brain: does not receive or transduce any light information

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3
Q

Optic chiasm definition:

A

Some axons cross to the contralateral side - decussation

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4
Q

Leaving the optic chiasm:

A

nerve bundles or optic tracts carry axons to the lateral geniculate nucleus(LGN) of the thalamus which relays info to the visual cortex

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5
Q

Decussation definition:

A

The crossing of nerve fibers from one side of the central nervous system to the other, commonly seen in the optic chiasm and pyramidal tracts

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6
Q

Optic tract definition:

A

a continuation of the optic nerve that extends from the optic chiasm to the lateral geniculate nucleus (LGN) and other brain regions, carrying visual information from the contralateral visual field.

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7
Q

Visual hemifield definition:

A

the half of the visual field (left or right) perceived by each eye, with information from each hemifield processed by the opposite side of the brain

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8
Q

Binocular visual field definition:

A

the area of the visual field where both eyes overlap in perception, allowing for depth perception and three-dimensional vision

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9
Q

lateral geniculate nucleus definition:

A

Ganglion cells project to the thalamus - the thalamic nucleus that receives information from the eye is the lateral geniculate nucleus of the thalamus(LGN)

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10
Q

optic radiation definition:

A

Optic radiation is a collection of nerve fibers that transmit visual information from the lateral geniculate nucleus (LGN) to the primary visual cortex in the occipital lobe.

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11
Q

What vision is kept/lost with damage to the left/right optic nerve?

A

Damage to the left optic nerve results in complete vision loss in the left eye, while damage to the right optic nerve causes complete vision loss in the right eye. However, vision from the unaffected eye remains intact, allowing partial visual field coverage

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12
Q

What vision is kept/lost with damage to the optic chiasm?

A

causes bitemporal hemianopia, meaning vision is lost in the outer (temporal) visual fields of both eyes, while the nasal (inner) visual fields are preserved. This occurs because the crossing fibers from the nasal retinas, which receive input from the temporal visual fields, are damaged

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13
Q

What vision is kept/lost with damage to the left/right optic tract?

A

Damage to the left optic tract causes right homonymous hemianopia, meaning vision is lost in the right visual field of both eyes.

Damage to the right optic tract causes left homonymous hemianopia, meaning vision is lost in the left visual field of both eyes

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14
Q

What vision is kept/lost with damage to the left/right lateral geniculate nucleus?

A

Damage to the left lateral geniculate nucleus (LGN) results in right homonymous hemianopia, causing vision loss in the right visual field of both eyes.

Damage to the right LGN results in left homonymous hemianopia, causing vision loss in the left visual field of both eyes.

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15
Q

What vision is kept/lost with damage to the left/right optic radiation?

A

Damage to the left optic radiation causes right homonymous superior quadrantanopia, meaning vision is lost in the upper right quarter of the visual field in both eyes.

Damage to the right optic radiation causes left homonymous superior quadrantanopia, meaning vision is lost in the upper left quarter of the visual field in both eyes.

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16
Q

What do retinal ganglion cell projections to structures other than the LGN do?

A

Hypothalamus: These projections help regulate circadian rhythms by transmitting light information to control the sleep-wake cycle.

Superior colliculus: These projections are involved in coordinating eye movements and directing attention to visual stimuli.

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17
Q

What is the single major target of the LGN?

A

The primary visual cortex (V1), is located in the occipital lobe, where visual information is processed for higher-level interpretation.

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18
Q

What is Retinotopy?

A

The spatial arrangement of visual information in the brain that mirrors the organization of the retina, where neighboring retinal cells correspond to neighboring areas in the visual cortex, preserving the topographical layout of the visual field.

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19
Q

What are 3 important points about Retinotopy?

A

Preserved Spatial Mapping, Foveal Representation, Functional Organization

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20
Q

What is Preserved Spatial Mapping?

A

Retinotopy ensures that neighboring neurons in the retina correspond to neighboring neurons in the visual cortex, maintaining the spatial organization of the visual field.

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21
Q

What is Foveal Representation?

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A

The fovea, the area of sharpest vision, is overrepresented in the visual cortex, occupying a larger area of cortical space compared to the peripheral visual field.

22
Q

What is Functional Organization?

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A

Retinotopy allows for efficient processing of visual information, as the brain can map and interpret visual input based on its spatial relationships in the retina.

23
Q

What are ocular dominance columns?

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A

Ocular dominance columns are vertical columns of neurons in the primary visual cortex that respond preferentially to input from one eye or the other, helping to process and integrate visual information from each eye for depth perception and binocular vision.

24
Q

What are binocular receptive fields?

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A

Areas in the visual cortex where neurons respond to both eyes, allowing for integration of visual information from each eye and enabling depth perception and stereoscopic vision.

25
What cells have binocular receptive fields?
Complex cells in the primary visual cortex (V1) have binocular receptive fields. They respond to visual stimuli from both eyes, help to process depth perception and stereoscopic vision.
26
What does orientation selectivity mean?
property of certain neurons in the visual cortex that respond most strongly to stimuli with a specific orientation, such as vertical or horizontal lines, and less strongly to other orientations.
27
What does the orientation column mean in terms of how V1 neurons respond?
respond preferentially to stimuli with the same orientation, such as vertical or horizontal lines. Neurons within a column are tuned to similar angles, and adjacent columns typically respond to slightly different orientations, creating a continuous map of orientations across the visual field.
28
What might orientation-selective neurons be specialized for in visual perception?
Specialized for detecting and processing the orientation of edges and contours in visual stimuli, crucial for object recognition, depth perception, and motion detection. These neurons help the brain analyze shapes, textures, and spatial relationships in the visual environment
29
What does direction selectivity mean in terms of how V1 neurons respond?
Property of certain neurons that respond most strongly to visual stimuli moving in a specific direction. These neurons are tuned to detect the motion of objects or edges, and their response weakens or becomes minimal when the stimulus moves in other directions.
30
What might direction-selective neurons be specialized for visual perception?
Specialized for detecting motion in the visual field, allowing the brain to perceive the movement of objects, track their direction, and process changes in the environment.
31
What are simple cells?
neurons in the primary visual cortex (V1) that respond to specific features of visual stimuli, such as edges, bars, or lines, at a particular orientation, position, and spatial frequency
32
What are complex cells?
neurons in the primary visual cortex (V1) that respond to visual stimuli with specific orientations and motion. They are sensitive to stimuli over a broader area and can respond to moving stimuli, regardless of their precise location within the receptive field
33
Why is the striate cortex called V1?
It's the first area of the visual cortex involved in processing visual information. The "V" stands for "visual," and "1" denotes its position as the primary visual area, receiving direct input from the lateral geniculate nucleus (LGN) and being the first stage of cortical visual processing.
34
What are the two large-scale cortical streams of visual processing?
The ventral and dorsal stream
35
The ventral stream:
(the "what" pathway), which is involved in object recognition, shape, color, and detail processing. It runs from the primary visual cortex (V1) to the inferior temporal lobe.
36
The dorsal stream:
(the "where" or "how" pathway), which is involved in spatial processing, motion detection, and guiding actions based on visual input. It runs from V1 to the parietal lobe.
37
Is it likely that you have neurons that recognize your grandmother and no one else?
Yes, it is likely that there are specialized neurons that respond selectively to highly specific stimuli, such as the face of a particular person, like your grandmother. These neurons would be part of a broader network of cells involved in face recognition and object identification
38
What is Isaac Newton's theory on color vision?
color vision and how the perception of color comes about changes in the world, done with a Hole in the shutter let light through and he held up a prism to let light through
39
What is white light?
White light has no inherent white color to it, just a mixture of 7 visible colors
40
What is the purpose of a glass prism?
refracts the white beam of light and each of the wavelengths has different refraction indexes and different refraction properties, which can be seen individually in the prism
41
What is the Trichromatic theory(1812)?
correct at the level of the photoreceptors: rods and cones The human retina in order to perceive all the different variations of colors emanates from different 3 “receptors” - responsible for color perception
42
What are Cocktail colors?
Some colors are a combination of 2 different cones to form a completely new one, 2 wavelengths simultaneously activate the cones
43
What are Tetrachromats?
4th cone for UV light - dramatic effect, color space turns 3D. Long, short, medium cones and the UV cones - 1 mil different shades for humans, tetrachromats have up to 100 million different color shades
44
What is the Opponent process theory(1878)?
Correct beyond photoreceptors - bipolar cells forward There are inherent pairings of colors and each member of this pairing is mutually antagonistic to the other - it inhibits the perception of its opposite color Explains why we don't see reddish/green or bluish/yellow colors
45
What happens when Greenlight inhibits?
hyperpolarizes the green cone, excises the horizontal cell, inhibits bipolar cell, inhibits ganglion cell
46
Red light excites:
hyperpolarizes the red cone, excites bipolar cells, excites ganglion cell
47
What neurotransmitter do horizontal cells use?
GABA when excited to inhibit the bipolar cell which leads to a decrease in the spontaneous activity of the ganglion cell - reduction 3Hz activity
48
Green cones have an m-opsin that picks up the green light:
it absorbs the green wavelength of light to hyperpolarize the green cone and removes the bread from the horizontal cell
49
What is the Visual receptive field?
for a ganglion cell is the patch of retina that when light shines on it, it influences the activity of the ganglion cell that its connected to
50
What is a Center-surround organization?
ganglion cell that gets excited by light stimulus in the center and gets inhibited by lights in the surrounding area of the receptive field - off center and off surround ganglion cell - same with color and light
51
How is the Central straight ahead vision accomplished?
by temporal hemiretina
52
How is the Peripheral surrounding area accomplished?
by nasal hemiretina

NRSC (5 decks)

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