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My Packs: IYNA (Neuroscience) > Lesson 5-6: Vision > Flashcards

Lesson 5-6: Vision Flashcards

(89 cards)

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1
Q

What is light?

A

A form of electromagnetic radiation visible to the naked eye

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2
Q

What is visible light?

A

The small set of wavelengths of electromagnetic that our eyes can detect

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3
Q

The ability to ______, _______, and _________ the information from visible light helps the organism to ___ the surrounding environment

A

Detect
Process
Interpret
See

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4
Q

Define:

Reflection

A

The change of direction or “bounce back” of a ray after encountering a new medium

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5
Q

Define:

Refraction

A

The bending of light when it is transferred between different mediums

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6
Q

Different _______ in the eye allow for __________ of light

A

Mediums

Refraction

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7
Q

Define:

Cornea

A

Transparent layer that forms the front of the eye and refracts light

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8
Q

Define:

Iris

A

Pigmentation provides colour for the eye

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9
Q

Define:

Lens

A

Bends light rays to form a clear image on the retina

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10
Q

Define:

Sclera

A

Tough wall of the eyeball

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11
Q

Define:

Aqueous Humour

A

Fluid filling the cornea

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12
Q

What is the aqueous humour fluid composed of? (2)

A

Salt

Water

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13
Q

Define:

Vitreous Humour

A

Fluid that provides support for the eye

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14
Q

What is the vitreous humour fluid composed of? (3)

A

Water
Salt
Protein

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15
Q

What is the function of extraocular muscles?

A

Moves the eye to let us shift focus without head rotation

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16
Q

The ______, ____, _______ and ________ _____ focus light onto ______

A 
Cornea
Lens
Aqueous
Vitreous humour
Retina
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17
Q

What do focusing errors cause? (2)

A

Nearsightedness

Farsightedness

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18
Q

Define:

Retina

A

Layer of tissue at the back of the eyeball with cells that respond to light and send signals to the brain

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19
Q

Define:

Optic disk

A

Origin of blood vessels; where optic nerve exits eye

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20
Q

True or False:

The optic disk has photoreceptors

A

False, the optic disk has no photoreceptors

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21
Q

Define:

Macula

A

Region of the retina densely filled with photoreceptors, contributes to central vision

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22
Q

Define:

Fovea

A

Sub region within the macula with very high visual acuity

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23
Q

The retina is a ________ membrane that lines the ____ of the ___

A

Sensory
Back
Eye

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24
Q

From photoreceptors, order the cells of the retina in order (5)

A 
Photoreceptors
Horizontal Cells
Bipolar Cells
Amacrine Cells
Retinal Ganglion Cells
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25
The optic nerve contains only ________ ____ _____. Other cell types ensure that ganglion cells are sending most _________ information to the _____
Ganglion cell axons Important Brain
26
Signal travels in an "______-___" manner in the ______, this produces _____ ____ where ganglion cells leave eye
Inside-out Retina Blind spot
27
Does the peripheral retina have a high ratio of photoreceptors to ganglion cells?
Yes
28
What is the ratio of photoreceptors to ganglion cells for the central retina?
Lower ratio of photoreceptors to ganglion cells
29
What does the central retina have lower ratio of photoreceptors to ganglion cells?
Good for fine detail
30
When _____ photoreceptors are connected to a _______ cell, finer details can be encoded by the ________ cell
Fewer Ganglion Ganglion
31
Describe the function of: | Rods (2)
For motion and black-and-white vision | Function well in low light
32
Describe the function of: | Cones (2)
Colour vision and central vision | Function best in medium-high light
33
Where are cones located?
Concentrated in the fovea
34
List the 4 steps of G-protein signalling
Neurotransmitter binds to receptor coupled with a G-protein Effector enzyme activated Second messenger molecules(s) activated Downstream effects result from chemical cascades
35
List the 3 steps of phototransduction in rods
In darkness, sodium channels gated by small molecule cGMP in rods constantly open and neurotransmitters constantly released Light activates signaling cascade which reduces intracellular cGMP Without cGMP, sodium channels close, membrane hyperpolarized, and signalling stops
36
True or False: | G Protein signalling cascade is similar in rods and cones
True
37
Unlike rods, _____ express photopigments that show sensitivity towards specific ___________
Cones | Wavelengths
38
Overlap in __________ _______ means brain must use information from all _____ to distinguish between ______
Absorption spectra Three Colours
39
True or False: | Bipolar and horizontal cells integrate signals from many photoreceptors
True
40
Define: | Receptive Field
Portion of the visual field that elicits activity by a single retinal ganglion cell
41
What is the function of receptive fields?
Allows ganglion cells to transmit information about the light being exposed to the photoreceptors
42
What are the components of the receptive field?
Center | Surround
43
Describe: | Center (Receptive Field)
Photoreceptors here synapse directly onto bipolar cells
44
Describe: | Surround (Receptive Field)
Photoreceptors here contribute indirectly by synapsing onto horizontal cells
45
Horizontal cells modulate _______ ________ ____ activity
Retinal Ganglion Cell
46
Horizontal cells form __________ synapses to modulate photoreceptor ______
Inhibitory | Output
47
True or False: | Horizontal cells are responsible for the difference in on and off bipolar cells
False, horizontal cells are NOT responsible for the difference in on and off bipolar cells
48
Where do signals travel from bipolar cells?
Retinal ganglion cells
49
How do retinal ganglion cells respond?
similarly to bipolar cells (if a bipolar cell is inhibited, the retinal ganglion cell will be less excited)
50
Visual information enters the brain via _____ _____
Optic nerve
51
________ cells that make up the optic nerve exit the eye at the _____ _____. Information from each ___ remains separate at first, but must be __________
Ganglion Optic disks Eye Integrated
52
What does decussate mean?
Cross
53
Axons decussate at the _____ ______ (left visual field to right __________, and vice versa)
Optic chiasm | Hemisphere
54
Where do optic tracts project before signals go to primary visual cortex? Why?
Thalamic structures | For intermediate processing
55
What is does the optic tracts go after intermediate processing?
Primary visual cortex
56
What does LGN stand for?
Lateral geniculate nucleus
57
What is the LGN? (2)
A portion of thalamus that processes visual information | Receives projections from optic nerve, and projects to visual cortex
58
___s map directly to ___ cells
RGC | LGN
59
Define: | RGC
Retinal ganglion cells
60
True or False: | The LGN is separated into 4 layers
False, the LGN is separated into 6 layers
61
What are the top four layers of the LGN called?
Parvocellular layers
62
What does the parvocellular layers do?
Receive inputs from small ganglion cells
63
What are the parvocellular layers sensitive to? (3)
Color Fine detail Slow moving objects
64
What are the bottom two layers of the LGN called?
Magnocellular layers
65
What does the magnocellular layers do?
Receive inputs from large ganglion cells
66
What are the magnocellular layers sensitive to?
Movement of objects
67
State the location of: | Parvocellular layers
Top four layers of the LGN
68
State the location of: | Magnocellular layers
Bottom two layers of the LGN
69
Starting from the optic tract, where does the visual inputs go?
Optic tract, to LGN, to Primary Visual Cortex (V1)
70
Neurons in __ are ___________ selective
V1 | Orientation
71
__ neurons respond optimally to _________ bar movements
V1 | Elongated
72
True or False: | The orientation of the bar determines strength of response of the neurons in V1
True
73
What is the orientation selective function of V1 for?
Motion and object shape detection
74
_________ inputs from ___ are separated in the ______ ______
Binocular LGN Visual cortex
75
What does the dorsal streams of V1 involve?
Involves area MT (medial temporal visual area)
76
What are the details about the neurons and cells in the MT? (2)
Neurons here have large receptive fields responsive to movement Cells here are direction selective
77
What does the ventral streams of V1 involve?
Involves area IT and V4
78
What is the details of the cells in the IT/V4?
Cells are orientation and color selective
79
What is the role of the ventral stream?
For sensing shape and color
80
What contributes to depth perception?
Binocular cues
81
Define: | Binocular cues
Visual information is taken from both eyes
82
In binocular cues, why is information taken from both eyes?
Information can converge to form a more accurate picture
83
In binocular cues, both eyes serve as individual _________ points to judge ________ and respond to ______ ____
Reference Distance Visual cues
84
To perceive the colour of an object as the same even under varying illumination, what does it require?
Requires illumination of varying wavelengths
85
How does do we achieve colour constancy? (3)
Cones register overlapping regions of light reflected by objects in scene Visual systems determines luminescence and discards Concludes "true" colour
86
Damage to MT or temporary inactivation causes what?
Deficits in visual motion perception
87
Optical flow field is computed and represented by _______ in area __
Neurons | MT
88
What is special about neurons in area MT?
They are selective for motion direction
89
What are neural responses in area MT correlated with?
They are correlated with the perception of motion

My Packs: IYNA (Neuroscience) (7 decks)

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