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Eyes and Visual Processing Flashcards

1
Q

What eye muscles are supplied by CN 3?

A

R –> S, I, M

O –> I

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2
Q

What eye muscles are supplied by CN 4?

A

Superior Oblique

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3
Q

What eye muscles are supplied by CN 6?

A

Lateral Rectus

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4
Q

What are the systems that control eye movement?

A

Oculomotor System: w head fixed

Head Movement System: when head moves (oculomotor and vestibular sytem)

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5
Q

What shape of movement must the patient move their eye in order to test the muscles in isolation?

A

Double H

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6
Q

SR and IR require the eyes to be ———- to test their function

A

Abducted

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7
Q

SO and IO require the eyes to be ——— to test their fucntion

A

Adducted

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8
Q

Midbrain reticular formation control movement of gaze in what plane?

A

Vertical via interactions of nerves 3 and 4

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9
Q

Pontine reticular formation control movement of gaze in what plane?

A

Horizontal Via the interaction of nerves 3 and 6

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10
Q

What is the MLF?

A

Medial Longitudinal Fasciculus –> White matter tract that connects several CN nuclei

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11
Q

what are the two types of neurons found in the gaze control pathway? and when do they signal?

A

Burst Neuron –> fire before movements

Ommnipause Neuron –>keep eyes in one position fire when there is no movement

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12
Q

how many types of bursting neurons are there and what do they do?

A

Excitatory: to Ipsilateral nuclei of different type
Inhibitory: to contralateral nucleus of same type

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13
Q

Of all the nerves controlling gaze which one is the only one that crosses the midline and supplies contralateral structures

A

Trochlear

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14
Q

what is optokinetic movement of the eyes?

A

holds image n the retina during sustained head movement

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15
Q

what does the vestibulo-ocular movement of the eye do?

A

holds image still in retina during brief head movements

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16
Q

if we want to move our eyes to the left which muscles must be activated?

A

R Medial Rectus (CN3)

L Lateral Rectus (CN6)

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17
Q

if we want to move our eyes to the left which nucleus must be activated first?

A

the left Pontine Reticular Formation

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18
Q

if we want to move our eyes to the left which nucleus must be inhibited first?

A

L CN3

R CN6

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19
Q

if we want to move our eyes to the left which nucleus must be activated second? third?

A

L CN6

and through the MLF the R CN3

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20
Q

if we want to move our eyes to the left which nuclei must be inhibited first? second?

A

R CN6

L CN3

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21
Q

information for eye movements comes mainly from?

A

Frontal Eye Fields Cortex

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22
Q

Frontal Eye Fields Cortex controls saccades in the ——– direction

A

Contralateral (aka activation of the right moves eyes to the left)

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23
Q

if there is a dissection of the Frontal Eye Fields Cortex gaze moves towards/away from lesion

A

Towards

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24
Q

What do the semicircular canals signal?

A

Head Position

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25
Otoliths in the ear sense what?
Linear acceleration
26
What are the otoliths?
Utricle and Saccule
27
the hair cells of the vestibular apparatus signal when there is desaceleration T/F
F, they do not signal when there is desaceleration or movement stops
28
In what direction must the fluid motion go in order to increase signalling in the semi-circular canals?
in the same direction of the semi-circular canal
29
if motion causes increased firing in one ear what does it cause in the other?
decreased signalling
30
Movement towards the right induces activation of the R vestibular nucleus T/F
T
31
Activation of the L vestibular nucleus inhibits the R abducens nucleus T/F
F. Causes activation of the R abducens nucleus in order to keep the image in the retina
32
What do the ganglion cell axons of the eye target?
Thalamus
33
What do the M ganglion cells 'see'
Magnocellular = Motion
34
What do the P ganglion cells 'see'
Parvocellular = Colour and Visual Acuity
35
What is in larger % M or P ganglion cells
P
36
The optic chiasm sits in front of the ----(1)----- and is surrounded by the ---(2)------
1 Pituitary | 2 Internal Carotids
37
What part of the RETINA does not decussate?
Temporal
38
What part of the VISUAL FIELD information does not decussate?
Nasal
39
Image on the left nasal visual field is seen by which optic cortex
Right
40
the thalamus is the relay center of all information except
olfactory information
41
Where is the cell body and nuclei of the ganglion cells located?
thalamus
42
Lateral Geniculate Nucleus (Thalamus) receives information related to what sense
Vision
43
Medial Geniculate Nucleus receives information related to what sense
Audition
44
Connection between Visual Cortex and LGN
Optic Radiations (White matter)
45
How many layers does the LGN have? and how many come from each eye
6 (3)
46
out of the six layers in the LGN to which do the M ganglion cells synapse?
1-2 (one of each eye)
47
out of the six layers in the LGN to which do the P ganglion cells synapse?
3-6 (two for each eye)
48
Where is the Primary Visual Cortex Located?
Occipital Lobe around the calcarine fissure
49
What is Retinotopic Organisation?
Cells from the retina that are close together tend to remain and signal to the same area
50
Which 1/2 visual field from each eye is projected in the contralateral eye?
Temporal
51
Where is foveal vision decoded?
at the most occipital part of the cortex
52
What artery supplies the primary visual cortex?
Posterior Cerebral Artery
53
Why does macular sparing occurs?
because the central vision of each eye in the cortex is supplied by a different artery
54
What are ipGC?
intrinsically photosensitive Ganglion Cells
55
What pigment is found in ipGC?
Melanopsin
56
if light is shinned on ipGC what happens?
Depolarisation and increased signalling
57
What muscle is under sympathetic activation in relation to the pupillary reflex?
Dilator Pupillae
58
What muscle is under parasympathetic activation in relation to the pupillary reflex?
Sphincter Pupillae (S parasympathetic)
59
Where do the ipGC signal to in order to code for circadian rhythm and sleep regulation?
Suprachiasmatic Nucleus (Hypothalamus)
60
Where do the ipGC signal to in order to code for pupillary response?
Pretectum (Midbrain) [Optical Pretectal Nucleus]
61
Where do the ipGC signal to in order to code for photophobia (allodynia)?
Posterior Nucleus of Thalamus | Dura ---Trigeminal --Brainstem---Thalamus
62
the efferent signal from the pupillary reflex comes from which nuclei?
Edinger-Westfal Nucleus
63
If there is an afferent defect would the ipsilateral pupil constrict? the contralateral? [in re to light]
No
64
If there is an efferent defect would the ipsilateral pupil constrict? the contralateral? [in re to light]
No, Yes
65
What do M cells decode?
Movement
66
In the visual cortex what layer is the sensory cortex for input of visual information?
Sensory cortex is always layer 4
67
Layer 4 is divided into 2 subdivisions they are? and what type of cells synapses there?
4Cα M | 4Cß P
68
Where do M and P cells target?
LGN (lateral geniculate nucleus)
69
Where is the first point where visual information gets combined?
Layer 4B
70
Where does information from the layer 4Cα gets relayed to? and what information is sensed here?
Layer 4B | Motion
71
What type of selectivity does the cells in layer 4B show?
Directional Selectivity: increased firing only on movement of light in a specific direction
72
Where is all visual information processed first in the brain?
Primary Visual Cortex (V1)
73
From the Primary Visual Cortex (V1) how many pathways can visual information take? what are they?
Where? --> Dorsal Pathway | What? --> Ventral Pathway
74
what type of cells signal their information via the WHERE pathway? and where is this pathway located?
Movement: M cells (codes for info above certain speed) | Middle Temporal Lobe [Area MT]
75
what type of cells signal their information via the WHAT pathway? and where is this pathway located?
Visual Acuity P cells | Inferior Temporal Lobe
76
The area MT receives what type of information and from where?
``` Motion Via V1(4B), V2 and V3 ```
77
Area MT has small receptive fields to better code for movement T/F
F Large visual fields
78
Define: Blind Sight
pathway from the LGN to the area MT that can be intact in some blind people allowing them to 'see' objects due to their movement
79
what is the visible range of light?
400-700 nm (430B,530G,560R)
80
ganglion cells react differently depending on where the light is shined on their RF T/F
T
81
What part of the visual cortex is mainly responsible for colour vision?
V4
82
in the area V4 cells have ----(1)---- selectivity and -----(2)---- selectivity
1 Orientation | 2 Colour
83
What is area IT important for? and is connected to what other important area?
Recognition of faces and Visual Memory | V4
84
What is a monochromat?
only one type of functional cone available
85
Define: Dichromat
2 types of functional cones
86
Anomalous Trichomacy is
3 types of cones but one expresses an abnormal pigment
87
How do you test for Anomalous Trichomacy?
Pseudoisochromatic Plates
88
What is the most common form of colour deficiency?
Anomalous Trichomacy
89
What does PROTAN stand for?
problems with the Red Cone PROTANope--> no red cone PROTANomal --> abnormal red cone
90
What does DEUTAN stand for?
problems with the green cone DEUTANope-> no green cone DEUTANomal--> abnormal green cone
91
What does TRITAN stand for?
problems with the blue cone TRITANope-> no blue cone TRITANomal--> abnormal blue cone
92
Can there be a monochromat protanomal with the other 2 cones intact?
No, monochromat only has 1 cone type
93
Can there be a trichromat protanomal with the other 2 cones intact?
Yes
94
What is visual acuity? what is the best result (normal)? what is legal blindness?
ability to distinguish fine detail (6/6) | 6/60
95
what is the last cell light hits when it enters the eye?
the photoreceptorvision in light (6/6)
96
what is phototopic vision?
vision in light (6/6)
97
what is scotopic vision?
vision without light (6/60)
98
What is the pathway for light to reach the photoreceptors?
Ganglion cell Bipolar cell Photoreceptors
99
what is the main photopigment found in cones and rods?
Rodopsin Conopsin there are less cones than rods and they are less sensitive
100
what is the main photopigment found in cones and rods?
the ganglion cells | glutamate
101
horizontal cells receive input and provide output to -----1----- and respond to light by -----2---- and releasing ----3---
1 photoreceptors 2 hyperpolarising 3 GABA
102
Amacrine cells allow for coding of ---1--- and are mostly ---2---
movement | 2 inhibitory
103
what are the modulatory cells of the eye?
amacrine and horizontal cells
104
in which layer are bipolar cells found? how many types are there?
Nuclear Layer 10 (9 for cones) Allow for colour vision and acuity
105
light ----1---- the photoreceptors induing a decreased release of ----2--- activating on/of ---3----
1 hyperpolarise 2 glutamate 3 ganglion cells
106
if light activates the horizontal cells there would be
hyperpolarisation and release of gaba
107
light activates ----1---- which in turns activates a -----2--- turning on a ----3--- reducing the levels of ----4--- closing ----5----
``` rhodopsin g-coupled protein phosphodiesterases cGMP cGMP dependant Na+ channels ```

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