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Flashcards in 12-5 VISION Deck (19):
1

A: Retina has 3 Functional layers of Neurons. The OUTER layer is made up of ______ and is adjacent to the __ ___. Intermediate layer = ______
innermost layer = _____ with _____ axons passing to CNS as the ____ _____

B: Why is the OUTER Distal part of Rods & Cones important?

C: FIRST Action Potential related to Vision occurs in __ ___ of the _________

A: Retina has 3 Functional layers of Neurons. The OUTER layer is made up of [RODS & CONES] and is adjacent to the [PIGMENTED EPITHELIUM]. Intermediate layer = bipolar interneurons.
innermost layer = ganglion cell bodies with afferent axons passing to CNS as the [OPTIC NERVE]

B: The OUTER Distal part of Rods & Cones contain photosensitive region and generation of RECEPTOR potential [NOT ACTION POTENTIAL]

C: FIRST Action Potential related to vision occurs in Afferent Axons of the [innermost ganglion cell bodies]

2

**DIFFERENCES BETWEEN RODS & CONES **
1. ____ are better for DAY Vision with ___[higher/lower] sensitivity to light. They Saturate only in _____ Light

2. ____ Capture MORE light and are great for _____ Vision and ______ light. ___ have ___[FAST/slow] response time and long integration.

3. Cones have Less photopigment AND Less amplification per cell
4. ___ are AChromatic and ____ are Chromatic ! Explain this

5. Which photoreceptor CAN'T do Bright Light?

1. CONES are better for DAY Vision with Lower sensitivity to light. They Saturate only in INTENSE Light

2. RODS Capture MORE light and are great for NIGHT Vision and Scattered light. Rods have slooow response time and long integration.

3. Cones have Less photopigment AND Less amplification per cell

4. Rods are AChromatic and Cones are Chromatic !
**Chromatic Cones = 3 types of photopigment in Cones (each sensitive to diff visible light spectrums --> Red/Blue/Green

**AChromatic Rods= ONLY 1 TYPE of photopigment in Rods

5. RODS CAN'T DO BRIGHT LIGHT

3

What forms the [Blood-Retinal barrier]

[Blood-Retinal barrier] = tight junction between Muller cells on Outer limiting membrane

4

A: How are the Bipolar Cells, Internueonrs & Ganglion cell bodies arranged near the Fovea? What about blood vessels?

B: How does Fovea and surrounding Macula receive metabolic supply?

C: Fovea is an _____[vascular/Avascular] retinal area with the ___[least/most] visual acuity. It has a __ ___ ____layer to prevent light barrier and is EXCLUSIVELY _____. There is a 1:1 ratio with [__:___] -which means ___ are more specific

D: Fovea is only __% of Retina and transmits __[least/most] of visual information to ________

A: Near Fovea, Bipolar Cells, Interneurons & Ganglion cell bodies are pushed LATERALLY-->makes a clear path for light = High visual acuity.
**Fovea is also Devoid of any blood vessels for same reason

B: Since Fovea is Devoid of any blood vessels, Fovea and surrounding Macula depend on diffusion from underlying choroid vessels for metabolic needs

C: The Fovea is an AVASCULAR retinal area with the MOST visual acuity. It has a laterally flat inner layer to prevent light barriers and is EXCLUSIVELY CONES. There is a 1:1 ratio with
[ganglion cell body: Cone receptor] -->Cones are more specific!

D: Fovea is only 5% of Retina but transmits MOST of visual information to [Lateral geniculate nucleus of thalamus]

5

A: What are the 7 Steps of Visual Pathway starting with light entering eye?

B: Light Entering Eye:
TEMPORAL Retina Fields pass _____ [crossed/uncrossed]
vs.
nasal retina fields pass ____ [crossed/uncrossed]

A: Pathway of Visual Info from Retina [RN CT L DV]
"RN (use) CT (to) Learn Direct Vision"
1. Light enters ---> hits Retina
2. Travels in Optic n.
3. Optic Chiasm [Nasal Retina Axons CROSS HERE]
4. Optic Tract
5.[ Lateral Geniculate Nucleus of Thalamus]
6. Optic RaDiations [Meyer's Temporal Loop vs. Parietal direct path]

7. [Area 17 -Calcarine Primary visual cortex]

B: Light Entering Eye:
TEMPORAL Retina Fields pass UNcRossed
vs.
nasal retina fields pass crossed @ Optic Chiasm

6

A: [P-type] ganglion cell bodies are used by _____. [M-type ganglion cell bodies are used by ______. Describe each of these
[3 each]

B: There are 4 LARGER ___-cellular layers and 2 smaller [___-cellular layers]. Why is this?

A: There are 2 MAJOR classes of [innermost ganglion cell bodies]
1. P-Type [USED BY CONES]
ºsmall bodies with 1:1 ratio to cones
ºsmall receptive fields --> BEST with [color/fine detail/high acuity]
ºtons of it near Fovea

2. M-type[used by rods]
ºLARGE Bodies and many axons share using 1 cell body
ºDense arborizations = Large receptive fields
ºBEST with [rapidly transient adaptation] &response to mvmnt or large objects

B: B: There are 4 LARGER Pravo-cellular layers and 2 smaller [magno-cellular layers] and this because there are WAAY MORE P-type ganglion cell bodies even though they're smaller .

7

A: Although Visual Perception begins in ______, collateral visual info enters ____ via Pretectal Area= for ___ _____ and _____ _____ for ________

B: Pretectal Area uses ___ nuclei of _____ for ___ _____ and projects both ipsilateral & contralateral via ____ _____

A: Although Perception of vision begins in [Area 17 CPVC] collateral visual info enters Brainstem via Pretectal Area=FOR PUPILLARY REFLEX and [SUP Colliculus]=For head&eye movement

B: Pretectal Area uses [Edinger-Westphal nuclei] of midbrain for PUPILLARY REFLEX and projects both ipsilateral & contralateral via POSTERIOR commissure

8

A: Optic Radiations project from ____ to the medial part of _____ cortex which surrounds _______

B: ..after entering the _______

1) lower visual field travels over _____ ventricle & ___ ____ via [__ _____ FIBERS] to terminate _____(above/below) [Calcarine Sulcus]

2) Upper visual field travels AROUND ___ _____ VIA [______] to terminate _____(above/below) [Calcarine Sulcus]

C: What's a good way to remember which Visual Field goes to which region of the eye?

A: Optic Radiations project from [lateral geniculate nucleus of thalamus]--->medial part of occipital cortex surrounding [Area 17 Calcarine-Primary visual cortex] or [Area 17 CPVC]

B: ..after entering [Lateral Geniculate Nucleus of thalamus]

1) lower visual field travels over lateral ventricle & Parietal lobe via [UPPER RADIATION FIBERS] to terminate ABOVE [Calcarine Sulcus]

2) Upper visual field travels AROUND temporal lobe VIA [LOWER RADIATION MEYER'S LOOP] to terminate below [calcarine sulcus]

C: Remember:
R visual field in R eye goes to Nasal which Crosses! "Right Right -->Nasal"

L visual field in L eye goes to Nasal which Crosses!

9

What would occur if there was a Lesion in ...
1. R Optic N. ---->

3. *Optic Chiasm ----->

4. R Optic Tract--->

5. R [lower radiation meyer's loop] -->

6. R [Lateral Geniculate nucleus of thalamus]-->

7. R [upper radiation fibers]

8. R [Area 17 CPVC]

B: Which 2 lesions present the same Visual sx?

Lesion in ... (using R side damage as example)
1. R Optic N. ----> BLIND RIGHT EYE
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3. *Optic Chiasm -----> [Bitemproal hemianopia](both temporal fields knocked out)
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4. R Optic Tract--->[CTL homonymous hemianopia] {Lose L-eye Temp} and {R- eye nasal}
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5. R [lower radiation meyer's loop] --> "Pie in the Sky Lesion' = [CTL homonymous upper quadrantanopia]
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6. R [Lateral Geniculate nucleus of thalamus]-->[CTL homonymous hemianopia]
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7. R [upper radiation fibers]-->[CTL homonymous LOWER quadrantanopia]
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8. R [Area 17 CPVC]--> [CTL homonymous hemianopia with macular/fovea sparing]
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**Lesions of Optic Tract and [Lateral Geniculate Nucleus of thalamus] PRESENT SAME VISUAL SX!

CTL = Contralateral (or L in this case)

10

What sometimes happens with car head traumas related to the fovea?

In automobile head traumas occipital pole is contused ---->impaired foveal vision (i.e. scotoma in center of visual field)

11

A: The Pupillary light Reflex involves a ___ reflex and ____ reflex. Describe each?

B: After light is shone thru 1 eye, BOTH pupils constrict becuz ___ connections to [_____ nucleus] from ____ fibers traveling thru [___ ____]--> activates [Oculomotor CN3] fibers to synapse in the ___ganglion and constrict ____ _____ m.

C: What part of the brain does this test?

D: Optic Nerve presents how? Why is this?
vs.
E: [Oculomotor Nerve damage] presents how? Why is this?

A: DIRECT reflex = light is shone thru R pupil and the R pupil constricts
CONSENSUAL reflex= light is shone thru R pupil BUT L pupil constricts also

B: both pupils constrict becuz bilateral connections to [Edinger-Westphal nucleus] from optic fibers traveling thru [SUP colliculus] activates [Oculomotor CN3] fibers to Ciliary ganglion--->constrict sphincter pupillae m.

C: Rostral Midbrain

D: Optic Nerve Damage----> EQUAL PUPILS becuz signal is NEVER sent to [Edinger-Westphal nucleus]= NO accomdation on either side
vs.

E: [Oculomotor CN3] damage--->[constricted pupil on 1 side and Dilated pupil on other]. Signal is sent from Optic N. but only 1 [Oculomotor CN3] is working = 1 sided constriction

12

A: In order to change gaze & focus on very close objects you need the ____ REFLEX which involves what 3 things?

B: Why does this reflex also involve the [Visual association cortex]?

C: How does your body know when this needs to be activated? [2]

In order to change gaze & focus on very close object you need the ACCOMMODATION REFLEX which involves..
1. eye convergence via [medial recti m.]
2. Ciliary m. constriction --->Lens thicken
3. Constriction of both pupils-->DEC light entering due to greater reflectance from close object

B: Involves [visual association cortex] because it is a CONSCIOUS act to change your gaze from far to near
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C: *[Visual Association Cortex] realizes something is "out-of-focus"-->sends signals (via internal capsule) to [supraoculomotor nuclei]--->generates motor control that bilaterally sends signals to Oculomotor complex

**Oculomotor complex uses [Edinger-Westphal nucleus] to control [ciliary ganglion]-->sends short ciliary n. to [ciliary m.] and iris sphincter
Oculomotor neurons control [medial recti m.]

13

A: Contracting ____ ____ m. from By Cranial Nerve __ in order to Blink in "BLINK REFLEX" protects eye and can be caused by what 3 things?

B: The Blink Reflex is consensual meaning______. It uses ___ ____ _____to relay ___ cornea information to ____ motor nuerons.

A: Contracting Facial CN7-[Orbicularis Oculi m.] in order to Blink in "BLINK REFLEX" protects eye and is caused by 3 things:
1. Bright light via CN2
2. Cornea stimulation(glabellar tap) via [CN 5B1]
3. Loud sounds via CN8

B: The Blink Reflex is consensual (Both eye lids will close in response to Cornea stimulation) and uses [reticular formation interneurons] to relay afferent cornea information to facial motor nuerons.

14

A: The Visual Cortex is unlike other Cortex areas in that it has_______ which allows _________ . It contains 3 HYPERCOLUMNS consisting of what 3 elements?

B: What is the [Parvocellular InterBlob]?

The Visual Cortex is unlike other Cortex areas in that it has a Greatly expanded input layer = allows fast processing of vast visual input . It contains 3 HYPERCOLUMNS made of:
1. Orientation cells-->assess spatial representations (edges)
2. Blobs-->color specificity
3. Occular Dominance ---> L vs. R
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B: Large pyramidal cells allowing cortex to send info about edges, fine details of what an object is & stationary objects to other CNS sites

15

A: What are the 2 ways to Detect Motion?

B: *Motion Perpendicular to orientation axis can be detected by____ ___ ____ but___ ____is needed for more complex movements **

2 ways to detect Motion
1. Image moves temporarily across retina while eye remains still = "temporal association"

2. [Head & Eyes] move to fix the [object image] onto the fovea

*Motion Perpendicular to orientation axis can be detected by Primary Visual Cortex but [V5 Temporal area] is needed for complex movements **

16

A: [T or F] Red, Blue and Green Colors all have their own Specific Cones to relay their wavelength information. Why or Why isn't this?

B: We need how many different photoreceptor types to perceive color? Why is this?

C: Why are there no "blue" cones in the fovea?

A: [FALSE] ALL CONES RESPOND TO ALL WAVELENGTHS OF LIGHT but a "Red" Cone will absorb MORE energy from a "RED" Photon/wavelength

B: We need at least 2 different photoreceptor types to perceive color because cortex compares differences in brightness and then assigns a "color" to the combination

C: Chromatic Aberration

17

A: Dorsal Streams of ______discriminative info from occipital cortex is sent to __ ___ ___ and contains info of ___ an object is = "_____ hierarchal parallel pathway"

B: Ventral streams from _______ discriminative info from occipital cortex is sent to ___ ____ ____and contains info of ____ an object is. = " ______hierarchal parallel pathways
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C: What is Visual Agnosia?
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D: What test do you you use for Color Blindness?

A: Dorsal Streams of visual info from occipital cortex is sent to POSTERIOR PARIETAL LOBE and contains info of WHERE an object is = "Magnocellular hierarchal parallel pathways"

B: Ventral streams from both Color & non-color discriminative info from occipital cortex is sent to [inferior TEMPORAL gyrus] and contains info of WHAT an object is. = [Parvocellular Blob] hierarchal parallel pathways
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C: Visual Agnosia= inability to identify objects due to lesion of [inferior temporal cortex]
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D: Ishihara test

18

Optic Radiation is AKA the _____ ______

Optic Radiation is AKA [Geniculocalcarine tract]

19

Cortical Layers
Layer 4 = ___ area

Layer 5 = ____ area

Layer 6 = __ _____

Cortical Layers
Layer 4 = input area

Layer 5 = MAJOR OUTPUT area

Layer 6 = Feedback pathway