12-5 VISION Flashcards
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]
- *DIFFERENCES BETWEEN RODS & CONES **
1. ____ are better for DAY Vision with ___[higher/lower] sensitivity to light. They Saturate only in _____ Light
- ____ Capture MORE light and are great for _____ Vision and ______ light. ___ have ___[FAST/slow] response time and long integration.
- Cones have Less photopigment AND Less amplification per cell
- ___ are AChromatic and ____ are Chromatic ! Explain this
- Which photoreceptor CAN’T do Bright Light?
- CONES are better for DAY Vision with Lower sensitivity to light. They Saturate only in INTENSE Light
- RODS Capture MORE light and are great for NIGHT Vision and Scattered light. Rods have slooow response time and long integration.
- Cones have Less photopigment AND Less amplification per cell
- 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
- RODS CAN’T DO BRIGHT LIGHT
What forms the [Blood-Retinal barrier]
[Blood-Retinal barrier] = tight junction between Muller cells on Outer limiting membrane
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]
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]
- [Area 17 -Calcarine Primary visual cortex]
B: Light Entering Eye:
TEMPORAL Retina Fields pass UNcRossed
vs.
nasal retina fields pass crossed @ Optic Chiasm
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
- 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 .
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
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!
What would occur if there was a Lesion in …
1. R Optic N. —->
- *Optic Chiasm —–>
- R Optic Tract—>
- R [lower radiation meyer’s loop] –>
- R [Lateral Geniculate nucleus of thalamus]–>
- R [upper radiation fibers]
- R [Area 17 CPVC]
B: Which 2 lesions present the same Visual sx?
Lesion in … (using R side damage as example)
- R Optic N. —-> BLIND RIGHT EYE
- ————————————————————————————- - *Optic Chiasm —–> Bitemproal hemianopia
- ————————————————————————————- - R Optic Tract—>[CTL homonymous hemianopia] {Lose L-eye Temp} and {R- eye nasal}
- ————————————————————————————- - R [lower radiation meyer’s loop] –> “Pie in the Sky Lesion’ = [CTL homonymous upper quadrantanopia]
- ————————————————————————————- - R [Lateral Geniculate nucleus of thalamus]–>[CTL homonymous hemianopia]
- ————————————————————————————- - R [upper radiation fibers]–>[CTL homonymous LOWER quadrantanopia]
- ————————————————————————————- - R [Area 17 CPVC]–> [CTL homonymous hemianopia with macular/fovea sparing]
- ————————————————————————————-
**Lesions of Optic Tract and [Lateral Geniculate Nucleus of thalamus] PRESENT SAME VISUAL SX!
CTL = Contralateral (or L in this case)
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)
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
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..
- eye convergence via [medial recti m.]
- Ciliary m. constriction —>Lens thicken
- Constriction of both pupils–>DEC light entering due to greater reflectance from close object
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.]
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:
- Bright light via CN2
- Cornea stimulation(glabellar tap) via [CN 5B1]
- 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.
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
————————————————————————————–
B: Large pyramidal cells allowing cortex to send info about edges, fine details of what an object is & stationary objects to other CNS sites
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”
- [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 **
