Exam 2 - Week 4 to 6 Flashcards
Which cells contain Opsin?
GC’s and PR’s
In the IPL, which cells synapse?
GC’s, Amacrine and BC’s
Which two cells in the retina provide an action potential?
GC and Amacrine
What type of processing occurs in the visual system?
Parallel Processing
Note: Starts from the beginning of the eye
What sides of the eye, crosses over at the Chiasm?
Nasal
If you have information from the left visual field, where in the LGN will it synapse?
Right LGN of the Thalamus
If you have a lesion at the Optic nerve of the right eye, what would be the effect?
Loss of all vision in the right eye
If you have a lesion at the Optic Chiasm, what vision would you lose?
Temporal visual field (Bitemporal Hemionopsia)
Note: The NASAL part of the retina is damaged or cannot relay the information
What is the most common clinical cause of a Bitemporal Heminopsia?
Tumor on the Pituatary Gland
What visual field is lost when there is a lesion at the right optic tract?
Visual information from the left visual field for both eyes will be lost - Left Homonymous
Where does Meyer’s loop dive into prior to going to the Occipital lobe?
Temporal lobe
What information does Meyer’s loop carry?
Information pretaining to the UPPER visual world
If there is a lesion at the right meyer’s loop, what is this lesion called?
Quadrantaopia
If there is a tumor in the Parietal lobe, what information is lost?
Inferior
If there is a lesion just prior to the LGN?
Effects periphery and part of the retina
Why is the central vision spared when there is a lesion at the primary visual cortex?
Foveal information is given superior compared to periphery.
What is Intensity based on in retinal images?
Wavelength, Time from both of the eyes
What are the Primary Sensory cues?
Luminance and Spectral (color information - processed in blobs and then into globs)
What are the feature based Sensory cues?
Contrast
2D velocity
Disparity
2D orieintation
What are the 4 inferred attributes?
- 3D form
- Surface properties
- 3D Spatial relationships
- 3D Movement
What are 3D forms of inferred attributes?
Shape, Size and Rigidity
What type of information do bistratified GC’s information send their information to?
Koniocellular (5%)
What type of information do Midget GC’s information send their information to?
Parvocellular
What type of information do Parasol GC’s information send their information to?
Magnocellular
How many layers are there in the LGN?
6
Magno = 1 and 2
Parvo = 2 to 6
From the ipsilateral side, what layers are impacted
2, 3, and 5
From the contralateral side, what layers are impacted?
1, 4 and 6
What layer of the LGN helps with color coding?
Parvo - from cones
What layer of the LGN helps with a sustained response?
Parvo
Note: Magno is transient
What layer of the LGN helps with high frequency sensitivity?
Magno
Which cells is faster than its counterpart, Magno or Pravo?
Magno
Which layer of the LGN has a high linearity?
Parvo - remember they are a cone base system
Which LGN layer has a higher response to contrast?
Magno - they are base on rods, thus they saturate fast
What cell represent the Parvo system?
4Ca
What source is for the Konio?
Blue cones
Note: Parvo would be the L and M cones
What is the largest amount of cells in the LGN system?
Magno - 95% (think of rods when you think of Magno)
When you have a transient system, goes on and then off and then on, what system is functioning?
Konio
What does the Frog’s eye tells the frog’s brain?
The frog has 4 cells
Contrast- Presence of a boundary
Convexity - tells you motion of an object I.e A fly
Movement detector-environment moving around it
Dimming detector - dimming in the largest area, weighted by distance from the the center.Ie. survival for protection.
What are two attributes about an X cell (Parvo)
Contrast and linear
Note: X cells have a null point, which is on the on light and off light response. Y cells cannot have a null point.
Note: Parvo cells are color OPPONENT….This means there is a different reaction to all wavelengths of color.
What are the two attributes about a Y-cell
Transient and non-linear (Magno)
What are the 2 attributes of the X-cell?
Sustained and linear (Parvo)
True or False, Magno cells are color opponent?
False.
Which cells are color opponent?
Konio and Parvo
True or False. GC’s are color selective?
True
What type of GC is connected to the Circadian Clock?
Melanopsin cells.
Note: Circadian clock is connected to Super Chiasmatic Nucleus
Are GC’s Orientation selective or Direction selective?
Direction selective - depends on where the light comes from.
What gives the GC its direction selection?
Axon to Dendrite
There are two types of movements that are prominent when reading?
Pursuit and Saccade
What type of GC cells do the Koniocellular input from?
Bi stratified
What parts of the brain are crucial with smooth pursuit eye movement?
Medial Temporal and frontal lobe (cognitive processing)
What is the optomotor cycle eye movement?
A cognitive process: Attention/Decision –> something moves and you have a reflex to fixate/track it –> stop and saccade back to new movement/stimulus
What part of a sentence takes the longest, beginning, middle or end?
Beginning
When we are having a conversation with an individual, which part of the face do we focus on the most?
Eyes
What is Dr. Cameron’s favorite band?
Ok Go - This is a test question
What is the greatest visual illusion?
Reading
What does the Brainstem encode?
Balance and Vestibular system
Note: Generate smooth pursuit and saccades.
What are the eye fields that project to the brainstem?
Frontal Eye Field, pre-frontal eye fields, parietal eye fields and Medial Superior Temporal (MST)
What are eye fields?
Collecting information from V1, V2 and V3
What visual pathway will include auditory information?
Parietal Frontal Eye Field
What area do CN 3, 4 and 6 communicate with?
the Brainstem
What is the primary visual pathway?
Contralateral eye (Medial) : LGN –> Area 17 (V1) –> (MT-MST-NOT) –> FEF (cognitive input) –> Brainstem nuclei/cerebellum (balance) –> CN 3 and 6 = saccades and pursuits
Note: The ipsilateral (Lateral) will get a direct input from NOT and give info to MT and MST, which then can give info to the brainstem nuclei (Pons)
Which region does nystagmus occur in?
Brainstem (Pons)
How do we test for Optokinetic Nystagmus (OKN)?
Moving a grating, which causes involuntary nystagmus
Note: If the grating cannot be controlled, then there is a problem in the visual system
What important vitamin is necessary for developing eye?
Vitamin A or Retinoic acid (derivative of Vitamin A - also meant for development of the eye)
Which two CN are the most important for generating smooth pursuit?
3 and 6
When building up for a saccade, what important nuclei is important for relaying information?
Pontine Nuclei
Which area is meant for fixation?
LGN, Area 17, MT and MST
area’s 17, 18, 19, 1, 2, 3, 5, 7 and 39
What is the visual cortex broad man areas?
17, 18 and 19
What is the primary visual cortex?
Broadman 17
Where are the visual eye fields located in the brain?
Pre-frontal lobe (area 8 - pre motor)
What is another name for the V1, other than the primary visual cortex?
Striate cortex
What sulcus does the Broadman 17 go deep into?
Calcarine Sulcus
If you dye the striate cortex, what eye would represent the black and the white section?
Black = right eye White = left eye
This is a vague question, sorry everyone.
What represents the black spot on the visual field representation?
Blind spot = Optic nerve
If the left visual cortex is being looked at, what part of the vision is being look at?
Right vision
What pathway does the Dorsal system take it to?
Magnocellular - “where pathway”
What pathway does the ventral system take it to the brain?
Parvocellular - “what pathway”
What are two distinct cells located in the Striate Cortex?
Simple and Complex cells
Once information has been sent to the LGN from GC’s, what cells take in the information prior to sending the information off to complex cells?
Simple cells
In the Hubel and Wiesel experiment, what type of GC had a diminished response to diffuse light?
On center GC
In the Hubel and Wiesel experiment, what type of GC had a strong response to diffuse light?
Off center GC
True or False, Simple cells are orientation selective?
True
Note: Test question
In the Hubel and Wiesel cells, what cells represented the X markings?
Off simple cells
Note: the x cells were the off cells
True or False, Simple cells have an antagonist off and on receptive field?
False. Antagonist = On and Receptive Field= Off
For edge detectors, they can see large areas and _____ areas
Fine area
Bar detectors. the can see _____ objects for certain larger areas
Smaller
What is the summation properties for simple cells?
Covering the inhibitory, you get more inhibitory. If you cover the excitatory you will get more excitatory
What is another term for mutual antagonism for simple cells?
Lateral inhibition
What gives you the strongest response for simple cells?
off region to on region and then to off region
What type of information does a GC send off to the V1 when you are trying to pay attention?
Rough Unstructured acquired data
What does it mean Dr. Cameron mentions Simple cells have mutual antagonism?
The off response will decrease the on response, while the on response will decrease the off response
What type of detector is our brain, contrast or luminance detector?
Contrast detector
Note: It remembers and compares things in terms of brightness and not actually how they are
True or False, the brain only interprets the lighting on the image not the light itself.
True
When observing the Hermann grid, you see little black dots at the square intersection, what part of the retina do the smudges occur?
Peripheral to the focal point
In regards to the Hermann Grid, what does between the blocks represent?
Great contrast selectivity
At the intersection of the Hermann grid, why are does that area appear darker (smudges)?
Greater Antagonism on the surrounds around the on center ganglion cells
Is the effect size dependent for ganglion cell theory?
According to the theory yes, but in reality there is NO effect shown for size dependency
Should contrast reversal cause the effect for ganglion cell theory?
Yes, contrast reversal should nullify the effect
Should the effect persist with a similar relationship between the stimulus and the receptive fields?
No, the effect does not persist with a similar relationship between the stimulus and the receptive fields.
Does the discharge and distribution of retinal ganglion cells fit?
No, discharge and distribution of retinal ganglion cells don’t fit
Does the spatial arrangement of receptive fields fit the hypothesis?
No.
Is the ganglion theory dependant on size?
No.
Note: Change the size, the illusion will persists
Is the ganglion cell reverse contrast, does the illusion go away?
No. The smudges on the right are black and on the left they are white
Looking at the scintillating grid, what is the most important part for this test?
Contrast, even in red and gray colors
Are ganglion cells orientation selective?
No
In regards to the Ganglion cell theory, does discharge fit?
No, we dark adapted and the illusion still presists
Does the spatial arrangement of receptive fields fit the hypothesis ?
No
What cells are responsible for ganglion cells theory illusion?
Simple cells
- Orientation selective
Which cell has a larger receptive field, Simple or Complex?
Complex
Are complex cells orientation selective?
Yes
Note: They are also direction selective
What are “hyper” complex cells sensitive to?
Stimulus length
Do complex cells have antagonistic receptive fields?
No, they are spatially invariant RF
What types of cells make up in V1, complex or simple?
Complex, 75% in Broadman 17, 18 and 19
What are the chances of flashes you can’t see, what is the accuracy occuring with blindsight?
4.66 x 10^14
If there is damage to V1 but the retina is fine, can the effected individual still detect anything?
Yes, the individual can detect location and movement
In which specific lobe module, do we have neurons that are selective for moving contours?
Hint: Flowing river analogy
MT lobe
What type of imaging is an important technique for understanding how cortical processing works?
fMRI
What is Akinetopsia?
Inability to detect motion
Where is the most common area for lesion to occur for visual neglect?
Parietal Lobe
