central visual pathways Flashcards
1
Q
How is the visual field bisected?
A
into left and right sides
2
Q
What happens to the left and right sides of the visual field?
A
each is projected to the opposite side of the brain.
3
Q
how is the visual field sent to opposite sides?
A
partial decussation of ganglion cells, visual fields project to opposite lateral geniculate body
4
Q
Where does visual field decussation happen?
A
optic chiasm
5
Q
What part of the visual field goes to both sides of brain?
A
fovea of retina, center of visual field
6
Q
What symptoms if you has lesion from one optic nerve?
A
total blindness in one eye, information would still go to both sides of brain from other eye
7
Q
What is hemianopsia?
A
loss of half of visual field
8
Q
two types of hemianopsia?
A
heteronymous and homonymous
9
Q
Heteronymous is what?
A
tunnel vision, loss of opposite visual field due to optic chiasm lesion
10
Q
Homonymous is what?
A
loss of same side visual field, optic tract lesion on way to LGN
11
Q
Where do the parvocellular and mangnocellular pathway got to and from?
A
Retina - LGN - Cortex pathway
12
Q
Cells of the parvocellular path?
A
midget- cones
13
Q
Cells of magnocellular path?
A
Parasol - rods
14
Q
Explain parvocellular path
A
Color, high resolution, slow, sustained
15
Q
Expain magnocellular path?
A
monochrome, low resolution, fast, transient
16
Q
How are the parvo,magnocellular pathways orientated?
A
Parallel paths LGN then cortex
17
Q
What path for object perception and ID?
A
parvocellular
18
Q
What path for motion, direction, alerting, etc?
A
magnocellular
19
Q
What type of cells are the parvo and magnocellular cells?
A
they are the specialized types of ganglion cells
20
Q
What type of specialized ganglion cell are there more of in optic nerve?
A
There are more parvocellular, midget cells, 95 percent
21
Q
What type of specialized ganglion recieves information from the larger group of bipolar,photoreceptor cells?
A
Magnocellular,parasol cells, about 5 percent of axons in optice nerve
22
Q
Does parvo or magnocellular have the largest center surround?
A
Magnocellular has the large center surround receptive fields cuz it has more photoreceptors
23
Q
How is the LGN arranged and what does that have to do with the parvo,magnocellular pathways?
A
LGN has 6 layers, the magno,parvo send their info to different layers.
24
Q
where is the primary visual cortex (VI)?
A
medial surface of occipital lobe.
25
How are the association visual areas, V2,3,5 arranged?
in concentric cortical areas around primary visual cortex
26
From what cells does Primal visual cortex develop perception of form, color and directon?
From the activity of simple and complex cells
27
The simple and complex cells that give VI info are arranged how?
in columns so that they can respond to certain bars,orientations of light.
28
What does a simple cell do?
Combine info from LGN cells, Respond to bars of light in specific orientations
29
What do complex cells do, where do they get their info?
Respond to bars of light in specific orientation, they get info from many simple cells
30
Do simple or complex cells respond to edges?
the simple cells respond to edges
31
What cells detect position and orientation of structure?
complex cell
32
What does hypercomplex cell do?
Detect endpoints and crossing lines
33
What cortex integrates simple, complex and hypercomplex cell info?
Secondary association cortex integrates information to generate sense of familarity of objects
34
Large receptive fields are sensitive to what?
sensitive to low spatial frequencies
35
What properties do visual cortical columns sort info into?
edge orentation, color, size, shape, direction, ocular dominance
36
What cells do visual cortical columns use to sort info?
simple and complex cells
37
How are visual vortical columns arranged?
vertical zies of cortex
38
What are "blobs"
Regions of cortex that Color opponent center surrounds RFs are sorted into
39
what to blobs process?
relative activities of color cells to form perceptial pallate.
40
what cortal area are blobs within?
withinvisual cortical columns
41
Complex cells in what layers of cortices generate depth perception?
complex cells in upper and lower layers of primary and association cortices.
42
can you get depth perception with just one eye?
yes but its by using visual cues
43
How is binocular depth perception determined?
retinal disparity and eye convergence
44
What is used to provide feedback onto sensory pathways?
complex activity generated by the cortical columns
45
What modulates LGN cells?
Brain stemp pathways using NE, AcH, NO
46
Cortical feedback to LGN shaes sensory input according to what?
behavior of the organism
47
What makes responses to light more discrete in the LGN?
cortical feedback, makes more difference between bars of light.
48
RF is what?
receptive field
49
What can enhance the LGN cortical transmission of stimulus?
cortical cells that respond optimally to particular receptive fields of light.
50
What chemical will enhance transmission of visual info by stimulating LGN and cortex?
NO and Ach that is released from the brain stem
51
No comes from where?
reticular foramen
52
Intense emotions can cause what of LGN?
seeing flashes of light.
53
What can modulatory activity do in LGN?
shift between arousal and sleep, waking up thalamus for attention
54
What stream is parvocellular stream?
The Ventral "what" stream is parvocellular, cones toward the temporal lobe
55
What stream is the magnocellular stream?
the Dorsal "where" stream is magnocellular, rods tword parietal.
56
The ventral stream is transmits infro from what area of retina?
the fovea, cones for acuity
57
The dorsal where stream transmids info from what area of retina?
From the peripheral retina, rods for action to answer how and where
58
Both the ventral and dorsal stream end up at the prefrontal cortex to do what?
converge to make working memory
59
Vi cortex projects what to association cortices?
orientation, spatial frequency, color
60
Why does VI project info to association cortices?
for integration into objects.
61
V2 is for what?
angles, illusiory contours, ground or figure
62
V4 is for what?
color and comlex shape, corners
63
Iferotemporal cortex is for what?
scale and position invariance, Faces
64
Middle temoral is for what?
Part of dorsal stream for detecting complex global motion
65
Inferotemporal cortex, IT responds to both halfs of visual field via what?
corpus callosum via interhemispheric axons
66
what does Inferotemporal neurons respond to?
complex shape,color, facial image, emotional expression
67
What part cortex is responsible for d?j? vu?
inferotemporal cortex
68
What can modify both long and short term memory for visual stimuli?
Modified by experience, impacted by hippocampus, amygdala,
69
What are the hippocampus and amygdala responsible for?
Limbic structures responsible for consolidating memories into cortex
70
What can modity activity of IT, inferotemporal cortex neurons?
attention, focus and you notice it more
71
What is visual neglect syndrome?
Loss of funciton in half of the visual association cortices
72
What is responsible for face recognition with emotional valence?
fusiform gyrus, faster than conciousness
73
What can fusiform gyrus cause if it malfunctions?
hallucinations
74
Synesthesia is what?
hereditary condition where experience different modalitys simultaneously, color numbers
75
Possible causes of synesthesia?
cross activation of neurons in fusiform gyrus
76
what are secondary visual pathways responsible for?
non concious visual responses and behavior
77
Where do ganglion cells project for secondary visual pathway?
Konicellulary to superior colliculus, melanopsin to pretectum and superchiasmic nucleus
78
Superior colliculus is for what?
visual orientatio, saccades, blindsight, emotion
79
Pretectum is for what?
pupillary reflex
80
superchiasmic nucleus is for what?
circadian fhythms
81
What ganglion cells for circidian rhythem and pupillary reflex?
melanopsin ganglion cells to pretectum and suprachiasmic nucelus
82
What ganglion cells for blindsight, emotion, saccades and visual orentation?
konicelluular to superior colliculus
83
Does konicellular ganglion have center surround fields?
nope, it has large receptive fields,
84
Where does superior colliculus pathway receive input from?
Konicellular ganglion, visual , auditory, association and motor areas of cerebral cortex
85
Where does superior colliculus pathway project info to?
saccaes eye movement areas, brain stem and spinal cord for head turning
86
what is the main function of superior colliculus pathway?
orient head and eyes to visual stimulus, where is it?
87
Saccaes are what?
quick, simultaneous movements of both eyes in same directions.
88
what directs saccadic eye movements?
cortiical eye field or superior colliculcu
89
Superior colliculus modulates what cranial nerves?
III, IV, VI
90
two sypes of saccades?
reflex - exogenously triggered, scanning - endogenous
91
when does seeing occur?
only between pauses of saccadic eye movement
92
what can cause blind sight?
lesion of primay visual cortex
93
what is blind sight?
lack of consciousness of visual information, but can still track, grasp point
94
what generates blind sight?
extrastriate midbrain pathway, visual input is directed to parietal areas to dorsal stream only
95
What system may explain blindsight phenomenon?
primitive visual system
96
Visual emotion pathway
konicellular - superior colliculuc - pulvinar of thalamus-amygdala - cingulate - orbitofrontal cortex
97
what does the pulvinar of visual emotional pathway do?
convey aversive emotional stimuli to amygdala, cingulate, aond orbitofrontal cortex.
98
Wht does amygdala do for visual emotional path?
Stimelates pathway for mental arousal and awarness.
99
Is the visual emotional pathway available in blindsight?
Visual emotional pathway is seen in blindsight
100
Externally perceved things involve activation of what?
activation of specialized visual areas
101
Internall percieved thing involve what?
activation of mostly frontal nad parietal areas
102
What is charles bonnet or deafferentations syndrome?
causes hallucinations from increased activity in fusiform face area or color center
103
What deficiency can maybe cause visual hallucinations?
cholinergic and serotonergic deficiency
104
What are the two levels of altered neural activity that cause hallucinatios?
activation of specific cortex or intercordical connections , neuromodulation of cortical areas by cholinergic and serotonergic paths from reticular formation.
105
Loss of cholinergic and serotonic inputs results in what type of hallucination?
more complex
106
What do intrinsically photosensitive retinal ganglion cells do?
mess with circadian rhythems because they absorm mostly blue light.
107
What nucleus has something to do with circadian rhythems?
suprachiasmatic nucleus
108
What type of ganglion cells project to SCN, suprachiasmic nucleus?
melanopsin ganglion cells,
109
what entrain SCN activity?
light and dark cycles
110
what does PVN, paraventricular hypothalamic nuclei affect after being affected by suprachiasmic axons?
sympathetic and parasympathetic systems, hypothalamic release of reproductive and stress hormones.
111
What do neurons in suprachiasmic nucleus specifically target?
peripheral clocks, pacemakers in skin, liver, pineal, adrenal etc.
112
What regluates release of melatonin?
SCN regulates pineal release of melatonin via SNS
113
what does melatonin regulate?
sleep wake cycle, temp, cortisol release, some organs.
114
when is melatonin released?
with decrease in light, it promotes sleep
115
what is pupillary light reflex for?
maintain right level of light into eye
116
what nuclei does the melanopsin ganglion cells activate?
pretectum, edinger-westphal nuclei in midbrain.
117
what does pretectal nucleus do?
coordinates both eyes, pupillary constriction
118
what activity increases light entry into eyes?
sympathetic activity
119
what muscle raises upper eyelid in response to Sympathetic activity?
tarsal muscle.
120
What activates dilator pupillae?
postganglionic superior cervical ganglion cells
121
what controls eyelid and iris dilation?
sympathetic control both locally and descending from limbic and hypothalamus
122
Horners syndrome?
drooping eyelids, ptosis, caused by damage to some aspect of SNS
