1.
Approximately how many areas of the brain have a visual function
Correct Answer
A. 45
Explanation
There are approximately 45 areas of the brain that have a visual function. These areas are responsible for processing and interpreting visual information received from the eyes. They play a crucial role in various visual processes such as object recognition, color perception, depth perception, and motion detection. The complexity and specialization of these areas allow us to have a rich and detailed visual experience.
2.
What percentage of the brain has a visual function
Correct Answer
A. 60%
Explanation
The correct answer is 60%. This means that approximately 60% of the brain is involved in visual functions. The brain is a complex organ responsible for processing and interpreting visual information, and a significant portion of its resources are dedicated to this task. Visual functions include tasks such as recognizing objects, perceiving depth and color, and interpreting visual stimuli. Therefore, it is important to understand that a large portion of the brain is dedicated to visual processing.
3.
Which of the following is the correct order for the number of variations of cells in the retina from most to least
Correct Answer
A. Amacrine > ganglion > bipolar > pHotorecepotors
Explanation
The correct order for the number of variations of cells in the retina from most to least is amacrine > ganglion > bipolar > photoreceptors. This means that the retina has the highest number of variations in amacrine cells, followed by ganglion cells, bipolar cells, and finally photoreceptors.
4.
Which of the following cells is most photosensitive to Red light
Correct Answer
A. L cones
Explanation
L cones, also known as long-wavelength cones, are most photosensitive to red light. These cones are responsible for detecting and perceiving longer wavelengths of light, including red light. They play a crucial role in color vision, particularly in perceiving and distinguishing red hues. L cones are most sensitive to light in the long-wavelength range, which corresponds to the red end of the visible light spectrum. This sensitivity allows them to absorb and respond to red light more effectively than other types of photoreceptor cells, such as M cones, S cones, or rods.
5.
Organize the following cellular functions into where in the cell they are performed for MOST OUTER to MOST INNER.
1. energy production.
2. activation of protein by light.
3. protein manufacturing.
4. contains cellular DNA.
5. transports ions and proteins
6. releases NT's
Correct Answer
A. 2, 5, 1, 3, 4, 6
6.
Rhodopsin makes up ~ ___________ % of entire disc in a rod
Correct Answer
A. 50
Explanation
Rhodopsin is a protein found in the rod cells of the retina that is responsible for the initial step in the process of vision. It is a key component in the conversion of light into electrical signals that can be interpreted by the brain. The statement suggests that rhodopsin makes up approximately 50% of the entire disc in a rod. This implies that rhodopsin plays a significant role in the functioning of rod cells and is a major component in the visual process.
7.
Which of the following is true regarding the environment inside a photoreceptor disc
Correct Answer
A. High [Na+]
Explanation
The correct answer is high [Na+]. This is because photoreceptor discs are part of the retina and are responsible for converting light into electrical signals. In order for this conversion to occur, there needs to be a high concentration of sodium ions (Na+) inside the photoreceptor disc. This high concentration of sodium ions helps to generate the electrical signals that are then transmitted to the brain for visual processing.
8.
Which of the following characteristics is true regarding photoreceptor cilium
Correct Answer
A. Cilium consists of 9 double microtubules that aid in the transportation of ions and newly made proteins
Explanation
The correct answer is that the cilium consists of 9 double microtubules that aid in the transportation of ions and newly made proteins. This is true because the cilium is a hair-like structure found on the surface of cells, including photoreceptor cells in the eye. It is composed of microtubules, which are cylindrical structures made of protein. These microtubules provide structural support to the cilium and also play a role in intracellular transport, including the movement of ions and newly synthesized proteins to different parts of the cell.
9.
Regarding photoreceptors; as you move eccentrically from the fovea, which of the following would be true (select all that apply)
Correct Answer(s)
A. Cone inner segment diameter increases with increasing eccentricity
C. Rods increase in population eccentrically
Explanation
As you move away from the fovea, the diameter of cone inner segments increases with increasing eccentricity. This means that the size of the inner segment of cone photoreceptors gets larger as you move towards the periphery of the retina. Additionally, rods, which are responsible for low-light vision, increase in population eccentrically. This means that there are more rods in the peripheral regions of the retina compared to the fovea. Therefore, both statements are true.
10.
Which of the following glial cells spans the entire retina (through all the layers)
Correct Answer
A. Muller's cells
Explanation
Muller's cells are a type of glial cells that span the entire retina, extending from the innermost to the outermost layers. They are responsible for maintaining the structural integrity of the retina, providing support to neurons, and regulating the extracellular environment. Muller's cells also play a role in the uptake and recycling of neurotransmitters, as well as in the regulation of retinal blood flow. Therefore, they are the correct answer to the question.
11.
Which of the following cells would you likely NOT find in the retina but WOULD FIND in the optic nerve
Correct Answer
A. Oligodendrocytes
Explanation
remember what is considered the optic nerve and what is considered the optic nerve head, oligodendrocytes provide myelination posterior to the lamina cribrosa of the ON, the astrocytes are present anterior to and up to the lamina cribrosa (dont provide myelination but rather control blood flow and maintain blood-ocular barrier)
12.
What are the 2 functions of astrocytes in the retina
Correct Answer(s)
A. Help hold blood vessels in place
B. Control blood flow out of vessels
Explanation
Astrocytes in the retina have multiple functions, including helping to hold blood vessels in place and controlling blood flow out of vessels. These functions are crucial for maintaining the structure and function of the retina. Astrocytes provide structural support to blood vessels, ensuring their stability and preventing them from moving or collapsing. Additionally, they regulate blood flow by constricting or dilating blood vessels, thus controlling the amount of blood that enters or exits the retina. These functions are essential for maintaining proper blood supply and nutrient delivery to retinal cells, ultimately supporting optimal vision.
13.
Why do we have so many vertical rod pathways????
Correct Answer
A. Allows rods to have an expanded range of response capabilities under different lighting conditions
Explanation
The reason we have so many vertical rod pathways is that it allows rods to have an expanded range of response capabilities under different lighting conditions. This means that the rods can effectively respond to a wider range of light levels, allowing us to see in various lighting environments. Having multiple pathways also helps to ensure that the rods can adapt and provide accurate visual information in different lighting conditions.
14.
Which of the following is NOT a vertical rod pathway
Correct Answer
E. Rod ---> OFF rod bipolar cell --> A2 amacrine cell --> OFF rod ganglion cell
Explanation
according to the lecture... rods do not have their own ganglion cells. they always connect to (in some way or another) ganglion cells that are connected to cones.
also, Rods only have 1 bipolar cell (ON)
15.
Which of the following cell bodies would be located in the distal INL, nearest the photoreceptors
Correct Answer
A. Horizontal cell bodies
Explanation
The correct answer is horizontal cell bodies. The distal INL (inner nuclear layer) is the layer closest to the photoreceptors in the retina. Horizontal cells are interneurons that receive input from photoreceptor cells and play a role in lateral inhibition, which enhances contrast and sharpens visual perception. Therefore, their cell bodies would be located in the distal INL, nearest the photoreceptors.
16.
Which of the following horizontal cell types projects to the fewest rods
Correct Answer
A. H1
Explanation
H1 is the only horizontal cell that has axonal connections to rods (~350-500)
all horizontal cells have a dendritic field that connect ONLY to Cones
17.
Which of the following ganglion cells may have a direct connection to mostly rods and aids in the function of visuomotor reflexes in animals
Correct Answer
A. Biplexiform-GC
Explanation
Biplexiform-GC is the correct answer because it is a type of ganglion cell that has a direct connection to mostly rods. This type of ganglion cell is involved in the function of visuomotor reflexes in animals, which suggests that it plays a role in coordinating visual information with motor responses. The other options, alpha-GC, beta-GC, gamma-GC, and ON-rod ganglion cell, do not specifically mention a direct connection to rods or involvement in visuomotor reflexes.
18.
Which of the following cells is responsible for the receptive field surround of ganglion cells
Correct Answer
A. Horizontal cells
Explanation
Horizontal cells are responsible for the receptive field surround of ganglion cells. Horizontal cells are specialized cells found in the retina that connect and communicate with photoreceptor cells, bipolar cells, and other horizontal cells. They help in the lateral inhibition process, which enhances the contrast and sharpness of visual perception. The receptive field surround refers to the area surrounding the center of the receptive field, and it is the horizontal cells that provide inhibitory signals to the ganglion cells in this surround region, helping to shape the center-surround receptive field structure.
19.
In the fovea; of the information that reaches the ganglion cells, what percentage is from amacrine cells directly
Correct Answer
A. 50%
Explanation
The correct answer is 50%. The fovea is the central part of the retina that contains a high density of cone cells responsible for detailed vision. Ganglion cells receive visual information from other cells in the retina, including amacrine cells. The question asks for the percentage of information that reaches the ganglion cells directly from amacrine cells. Since the question does not provide any additional information, we can assume that 50% of the information reaching the ganglion cells comes directly from amacrine cells.
20.
Which of the following was discovered to be primarily involved with the changes that occur in the receptive fields of ganglion cells with dark adaptation?
Correct Answer
A. Interplexiform neurons
Explanation
Interplexiform neurons are primarily involved with the changes that occur in the receptive fields of ganglion cells with dark adaptation. These neurons connect different layers of the retina and play a role in transmitting signals between different types of retinal cells. During dark adaptation, interplexiform neurons help to adjust the sensitivity of ganglion cells to light by modulating the signals received from photoreceptor cells. This allows the ganglion cells to adapt to low light conditions and enhance their ability to detect and transmit visual information.
21.
Which of the following would be an appropriate reason why your visual acuity is decreased when going from photopic conditions to scotopic conditions
Correct Answer
A. Increased receptive field size
Explanation
When transitioning from photopic conditions to scotopic conditions, the visual system adjusts to low light levels. In scotopic conditions, the increased receptive field size allows for the capture of more photons, enhancing sensitivity to low light. This expanded receptive field size enables the eye to gather more light from the surroundings, compensating for the reduced amount of available light in scotopic conditions. As a result, visual acuity decreases due to the larger receptive field size, which leads to a decrease in the sharpness and clarity of the image perceived.
22.
Which of the following would NOT be an expected number of invaginations of a cone pedicle in which horizontal cells and bipolar cells can synapse
Correct Answer
A. 29
Explanation
cone pedicles have ~ 12-25 invaginations
23.
Which one of the following pairs of cells CANNOT communicate within/on a given cone pedicle
Correct Answer
A. Horizontal cell <--> midget bipolar cell
24.
What are the 2 parts of a ribbon synapse
Correct Answer(s)
A. Synaptic lamellae
B. Arciform density
Explanation
The two parts of a ribbon synapse are synaptic lamellae and arciform density. Synaptic lamellae refer to the layers of membrane that surround the synaptic ribbon, while arciform density is a specialized electron-dense structure found in the synaptic cleft. These two components play important roles in the transmission of signals between neurons at ribbon synapses.
25.
Typically how many invaginating rod bipolar cells are found in a spherule?
Correct Answer
A. 2
Explanation
In a spherule, typically there are two invaginating rod bipolar cells. These cells are responsible for transmitting signals from the rod photoreceptor cells to the bipolar cells in the retina. The spherule is a specialized structure in the retina where the rod photoreceptor cells connect with the bipolar cells. Therefore, it is expected to find two invaginating rod bipolar cells in a spherule.
26.
At each adherent junction, there are about
Correct Answer
A. 3 gap junctions
Explanation
At each adherent junction, there are about 3 gap junctions. Gap junctions are specialized protein channels that allow for direct communication and exchange of molecules between adjacent cells. Adherent junctions are cell-cell adhesion complexes that help cells adhere to each other and provide mechanical strength to tissues. The presence of 3 gap junctions at each adherent junction suggests a high level of communication and coordination between adjacent cells, which is important for tissue function and homeostasis.
27.
Which of the following groups of cells would most commonly be found synapsing together in the IPL
Correct Answer
A. 1 ganglion cell, 1 amacrine cell, 1 bipolar cell
Explanation
In the inner plexiform layer (IPL) of the retina, the most common group of cells that would be found synapsing together is 1 ganglion cell, 1 amacrine cell, and 1 bipolar cell. Ganglion cells receive input from bipolar cells and amacrine cells provide lateral inhibition and modulate the signal transmission between bipolar and ganglion cells. Therefore, this group of cells is commonly found synapsing together in the IPL.
28.
A ________________ synapse is one between amacrine and bipolar cells in which a feedback loop is created
Correct Answer
reciprocal
Explanation
A reciprocal synapse is one between amacrine and bipolar cells in which a feedback loop is created. This means that the communication between these cells is bidirectional, with signals being transmitted back and forth. This type of synapse allows for a more complex and dynamic interaction between the amacrine and bipolar cells, enhancing the processing and integration of visual information in the retina.
29.
Which of the following with the correctly ordered set regarding feline ganglion cells and dendritic spread from largest to smallest
Correct Answer
A. AlpHa- GC > Gamma GC > Beta GC
Explanation
The correct answer is Alpha- GC > Gamma GC > Beta GC. This means that the feline ganglion cells are ordered from largest to smallest in terms of dendritic spread. Alpha- GC has the largest dendritic spread, followed by Gamma GC, and then Beta GC.
30.
In felines, which 2 ganglion cells are highest in quantity
Correct Answer
A. AlpHa and Beta
Explanation
In felines, the ganglion cells that are highest in quantity are Alpha and Beta.
31.
What is the first cell in the visual pathway to produce an action potential
Correct Answer
A. Amacrine cell
Explanation
The amacrine cell is the first cell in the visual pathway to produce an action potential. It is a type of retinal neuron that receives signals from bipolar cells and sends them to ganglion cells. The ganglion cells then transmit the visual information to the brain via the optic nerve. The action potential generated by the amacrine cell allows for the transmission of visual signals from the retina to the brain for further processing and interpretation.
32.
Which of the following is the correct membrane resting potential of a rod
Correct Answer
A. -20mV
Explanation
The correct membrane resting potential of a rod is -20mV. The resting potential refers to the electrical charge across the cell membrane when the cell is at rest. In the case of a rod, the resting potential is -20mV, indicating that the inside of the cell is more negative compared to the outside. This potential is maintained by the balance of ion concentrations and the activity of ion channels in the cell membrane.
33.
Which of the following is the correct membrane potential after a rod has been stimulated by light
Correct Answer
A. -60mV
Explanation
The correct membrane potential after a rod has been stimulated by light is -60mV. This is because when a rod is stimulated by light, it hyperpolarizes, meaning the membrane potential becomes more negative. The resting membrane potential of a rod is typically around -40mV, so when it is hyperpolarized by light, it becomes even more negative, reaching -60mV.
34.
Which of the following is the only chemical change that occurs in response to light
Correct Answer
A. Rhodopsin ---> bathorhodopsin
Explanation
Rhodopsin is a pigment found in the rods of the retina that is responsible for vision in low light conditions. When rhodopsin absorbs light, it undergoes a chemical change and is converted into bathorhodopsin. This conversion is the only chemical change that occurs in response to light. The other options listed involve the breakdown or conversion of rhodopsin into different compounds, but they do not specifically occur in response to light.
35.
Which of the following cells in the visual pathway undergo hyperpolarization (select all that apply)
Correct Answer(s)
A. pHotoreceptors
B. OFF bipolar cells
C. Horizontal cells
Explanation
Photoreceptors, OFF bipolar cells, and horizontal cells undergo hyperpolarization in the visual pathway. Photoreceptors are the first cells in the pathway that convert light into electrical signals, and they hyperpolarize in response to light stimuli. OFF bipolar cells receive input from photoreceptors and also undergo hyperpolarization. Horizontal cells, which are responsible for lateral inhibition and contrast enhancement, also hyperpolarize. Ganglion cells, amacrine cells, and ON bipolar cells do not undergo hyperpolarization in the visual pathway.
36.
"a given optic nerve fiber responds to light only of a particular region of the retina receives illumination. this region is termed the receptive field of that fiber."
the above definition does NOT apply to which of the following cells
Correct Answer
A. Biplexiform cell
Explanation
the above receptive field definition can be summed up as... "the area on the retina from which the neural discharge of a neuron can be influenced by light stimulation"
"this definition is applicable to any visual neuron"
the biplexiform neuron is NOT AN IMAGE FORMING NEURON. therefore this definition does not apply
37.
If a large light stimulus were to fall within the area of 2 adjacent receptive fields. which of the following would you expect
Correct Answer
A. Sub-optimal response
Explanation
If a large light stimulus were to fall within the area of 2 adjacent receptive fields, one would expect a sub-optimal response. This is because the receptive fields are responsible for detecting and responding to specific stimuli within their designated areas. When a large stimulus falls within the area of two adjacent receptive fields, it may not be accurately detected or processed by either field, leading to a sub-optimal response.
38.
Which of the following is a good test for x-cell function
Correct Answer
A. Visual acuity
Explanation
Visual acuity is a good test for x-cell function because it measures the clarity and sharpness of vision. X-cell function refers to the ability of the cells in the retina to detect and transmit visual information to the brain. Visual acuity tests assess the ability to see fine details and distinguish between different objects or letters at a given distance. Therefore, a good visual acuity indicates that the x-cell function is working properly, as the individual can perceive and interpret visual stimuli accurately.
39.
Which of the following ganglion cells project to the superior colliculus
Correct Answer
A. W cells
Explanation
W cells are a type of ganglion cells in the retina that project to the superior colliculus. These cells are responsible for transmitting visual information related to motion and are involved in the control of eye movements. The other options, x-cells, beta-cells, y-cells, and alpha cells, do not project to the superior colliculus.
40.
Which of the following is the correct order of ganglion cell conduction velocities from slowest to fastest
Correct Answer
A. W < X < Y
Explanation
The correct order of ganglion cell conduction velocities from slowest to fastest is W < X < Y.
41.
Which of the following ganglion cell types account for 80% of all ganglion cell types
Correct Answer
A. P beta
Explanation
P beta ganglion cells account for 80% of all ganglion cell types.
42.
Parvocellular ganglion cells and magnocellular ganglion cells account for ____________ % of all ganglion cells in the retina
Correct Answer
A. 90%
Explanation
Parvocellular ganglion cells and magnocellular ganglion cells are two types of ganglion cells found in the retina. These cells are responsible for transmitting visual information from the retina to the brain. The given answer, 90%, suggests that these two types of ganglion cells collectively account for 90% of all ganglion cells in the retina. This indicates that they are the major types of ganglion cells and play a significant role in visual processing.
43.
Which of the following layers of the lateral geniculate nucleus do M-cells project to (select all that apply)
Correct Answer(s)
A. 1
B. 2
Explanation
M-cells are a type of retinal ganglion cells that project to the magnocellular layers (layers 1 and 2) of the lateral geniculate nucleus. These layers are responsible for processing information related to motion, depth, and low spatial frequency. Therefore, M-cells project to layers 1 and 2 of the lateral geniculate nucleus.
44.
Nasal ganglion cell axons from the right eye synapse on which of the following areas of the LGN
Correct Answer
A. Left LGN areas 1, 4, & 6
Explanation
The correct answer is left LGN areas 1, 4, & 6. This is because the question states that the nasal ganglion cell axons from the right eye synapse on the LGN. Since the nasal ganglion cells carry information from the contralateral (opposite) eye, the axons from the right eye would synapse on the left LGN. The areas 1, 4, & 6 of the left LGN receive input from the contralateral eye, making them the correct answer.
45.
Ganglion cell axons from ________________visual field project towards the posterior aspect of the LGN
Correct Answer
A. Vertical midline
Explanation
Ganglion cell axons from the vertical midline of the visual field project towards the posterior aspect of the LGN. This means that the ganglion cells located in the central part of the visual field, along the vertical midline, send their axons to the back part of the lateral geniculate nucleus (LGN). The LGN is a relay station in the thalamus that receives visual information from the retina and sends it to the visual cortex for further processing.
46.
The central ________ degrees of the visual field projects to a very large area of the LGN, "the more machinery devoted to a particular area the better the vision"
Correct Answer
A. 20
Explanation
The central 20 degrees of the visual field projects to a very large area of the LGN. This means that there is a significant amount of neural machinery dedicated to processing information from this specific area. As a result, vision in this region is likely to be more precise and detailed compared to other areas of the visual field.
47.
Which of the following is(are) characteristics/functions of type II cell in the parvocellular layers (select all that apply)
Correct Answer(s)
A. Fewest of the parvocellular cells
B. Color opponent organization without a center surround
Explanation
the parvocellular layers contain type 1, 2, 3 LGN neurons
parvo type 1 = most common parvo cell, center surround with simple color opponent organization, smallest receptive field, linear
parvo type 2 = fewest of parvo cells, color opponent organization without a center surround, can be linear or non linear
parvo type 3 = 2nd most common parvo cell, achromatic with center surround can be linear or non linear
the magnocellular layers contain type 3 and 4 cells
magno type 3 = achromatic center surround organization with larger RF than parvo type 3, non linear
magno type 4 = rarest, large RF center with surround, center is ON type responsive to "any wavelength" surround is OFF to long wavelengths
48.
Which LGN neurons are responsive to color (select all that apply)
Correct Answer(s)
A. Parvo type 1
B. Parvo type 2
H. Magno type 4
Explanation
Parvo type 1 and parvo type 2 LGN neurons are responsive to color because they receive input from the cones in the retina, which are responsible for color vision. Magno type 4 LGN neurons are also responsive to color because they receive input from the parvo type 1 and parvo type 2 neurons, which encode color information. The other options, parvo type 3, parvo type 4, magno type 1, magno type 2, and magno type 3, are not associated with color processing.
49.
Which LGN neurons are or can be linear (select all that apply)
Correct Answer(s)
A. Parvo type 1
B. Parvo type 2
C. Parvo type 3
Explanation
The LGN (Lateral Geniculate Nucleus) is a structure in the thalamus that receives visual information from the retina and relays it to the visual cortex. LGN neurons can be classified into two main types: parvo and magno. Parvo neurons are responsible for processing color and fine details, while magno neurons are responsible for processing motion and large-scale features. The question asks for the types of LGN neurons that are or can be linear. Linear neurons are those that have a linear response to the input stimulus. Since the question does not provide any specific information about the linearity of each neuron type, we can assume that all parvo types (1, 2, and 3) can be linear. Therefore, the correct answer is parvo type 1, parvo type 2, and parvo type 3.
50.
Neurons in the LGN project to which layer(s) of the visual cortex
Correct Answer
D. IV
Explanation
Neurons in the LGN (Lateral Geniculate Nucleus) project primarily to layer IV of the visual cortex. This is supported by anatomical studies that have shown a direct connection between the LGN and layer IV. Layer IV is known as the primary receiving layer of the visual cortex, where it receives and processes visual information from the LGN. Other layers of the visual cortex (I, II, III, V, VI) may also receive inputs from the LGN, but layer IV is the main target for these projections.