The human visual system is especially good at detecting _____ whether it be luminance, chromatic or timing, allowing the brain to perceive color, edges, shadows, depth and motion.
contrast
Which of the following is NOT TRUE about the visual system?
1. Most important objects that humans interact with on earth reflect light in the visible light spectrum
2. Information from the left visual field is transmitted to the right thalamus and right visual cortex
3. About half of the optic nerve axons decussate at the optic chiasm
4. The eye/retina is considered part of the central nervous system
5. The eye/retina detects light in the visible light spectrum from 100 to 1000 nm
The eye/retina detects light in the visible light spectrum from 100 to 1000 nm
Which of the following is NOT TRUE about photoreceptor cells?
1. Photoreceptor cells can detect light to provide photopic, mesopic or scotopic vision
2. If damaged, photoreceptor cells can not be replaced from progenitor cells, and this can lead to blindness
3. Light is detected by photoreceptor cells after passing through other neuronal and synaptic layers in the retina
4. Photoreceptor cells communicate with bipolar neurons and horizontal cells using synaptic transmission
5. Photoreceptor cells have regions called inner segments that contain the disc membranes
Photoreceptor cells have regions called inner segments that contain the disc membranes
Which of the following is NOT TRUE about the “dark current” (DC) components in photoreceptors in dark?
1. The DC leads to persistent opening of voltage gated Ca2+ channels at the presynaptic region
2. The DC ensures a resting membrane potential of between -30 and -40 mV
3. The DC produces a constant release of the neurotransmitters GABA and glutamate by photoreceptor cells
4. The DC involves an outward leak K+ current in the inner segment
5. The DC involves the cGMP dependent inward Na+/Ca2+ current in the outer segment
The DC produces a constant release of the neurotransmitters GABA and glutamate by photoreceptor cells
Which of the following is NOT TRUE about cGMP gated channels (cGGC) in rod photoreceptors?
1. when cGGC close, this leads to hyperpolarization of the membrane potential in response to light
2. cGGC are a type of voltage gated ion channels which are opened when the membrane is depolarized
3. When open, cGGC allow Na+ and Ca2+ to flow down their electrochemical gradient and depolarize the membrane potential
4. cGGC are involved in both the dark current and response to light
5. cGGC are localized at the plasma membrane in rods and cones
cGGC are a type of voltage gated ion channels which are opened when the membrane is depolarized
Which of the following is NOT TRUE about the phototransduction response to light?
1. the cyclic GMP gated channels open when cyclic GMP levels decrease
2. the level of cyclic GMP is decreased by cGMP phosphodiesterase (PDE)
3. the G protein called transducin is activated when transducin alpha binds GTP and releases beta-gamma
4. 11-cis retinal absorbs a photon, which causes a conformational change in rhodopsin and activates it
5. the membrane potential becomes hyperpolarized
the cyclic GMP gated channels open when cyclic GMP levels decrease
Similar to the somatosensory system, an important function for adaptation of the phototransduction cascade is to ____.
1. all of these answers
2. increase the dynamic range of the stimulus
3. increase sensitivity to all stimuli
4. prevent photodamage to the retina
5. reduce the signal to noise ratio
increase the dynamic range of the stimulus
Photoreceptor cells (rods and cones) release ______ in response to light.
1. more glutamate and retinal
2. more or less glutamate, depending on the receptive field
3. more or less glutamate, depending on the type of photoreceptor type
4. less glutamate
5. more glutamate
less glutamate
Which of the following is NOT TRUE about rods and cones?
1. Rods express rhodopsin while cones express one of three photopsins
2. Rods are more sensitive to light than cones are, but saturate in bright light
3. Cones saturate in bright light but rods do not
4. Rods have slower temporal responses than cones do
5. Rods are localized outside the fovea in the periphery while cones are localized in both the fovea and the periphery
Cones saturate in bright light but rods do not
____ photoreceptor cells are involved in high acuity vision because ____.
1. Cone, cones are concentrated in the fovea
2. Both rod and cone, both are necessary to respond over the visual spectrum
3. Both rod and cone, high acuity vision requires both photopic and scotopic vision
4. Rod, rods are more sensitive to light
5. Both rod and cone, they have different properties and wavelength maxima
Cone, cones are concentrated in the fovea
Which of the following is NOT TRUE about retinal pigment epithelial cells (RPEs)?
1. they absorb photons to reduce light scattering
2. they to help repair and recycle photodamaged components
3. they are progenitor cells that differentiate into photoreceptor cells
4. they have been implicated in retinitis pigmentosa and macular degeneration
5. they phagocytose rod and cone outer segments
they are progenitor cells that differentiate into photoreceptor cells
The center-surround receptive fields in bipolar and retinal ganglion cells contribute to detecting ____.
1. movement
2. boundaries, edges and shadows
3. color
4. contrast
5. all of these answers
all of these answers
The center-surround receptive field is essential to provide contrast ____.
1. all of these answers
2. that is a basis of many different aspects of vision
3. in many regions of the visual field
4. in both low and high light conditions
5. that involves both rods and cones
all of these answers
On-center bipolar neurons express______ receptors, which lead to _____ in response to light in the center.
1. AMPA receptors, hyperpolarization
2. glutamate, a decrease in glutamate release
3. mGluR6 receptors, depolarization
4. NMDA receptors, an increase in Ca2+ levels
5. rhodopsin, decrease in cGMP levels
mGluR6 receptors, depolarization
An increase in light in the center of an On-center bipolar cell leads to _____ in retinal ganglion cell axons.
1. a decrease in the frequency of action potentials
2. an increase in the frequency of action potentials
3. no change in the frequency or rate of conduction of action potentials
4. a decrease in the rate of conduction of action potentials
5. an increase in the rate of conduction of action potentials
an increase in the frequency of action potentials
Off-center bipolar neurons express ______ receptors, which leads to _____ in response to light in the center.
1. AMPA receptors, hyperpolarization
2. glutamate, an increase in glutamate release
3. NMDA receptors, an increase in Ca2+ levels
4. rhodopsin, decrease in cGMP levels
5. mGluR6 receptors, depolarization
AMPA receptors, hyperpolarization
An increase in light in the center of an Off-center bipolar cell leads to _____ in retinal ganglion cell axons.
1. an increase in the rate of conduction of action potentials
2. a decrease in the frequency of action potentials
3. no change in the frequency or rate of conduction of action potentials
4. a decrease in the rate of conduction of action potentials
5. an increase in the frequency of action potentials
a decrease in the frequency of action potentials
____ cells are GABAergic inhibitory interneurons that mediate and control the surround response to light.
1. Horizontal
2. Photoreceptor
3. Bipolar
4. Retinal ganglion
5. Retinal pigmented epithelial
Horizontal
The human visual system can detect light over a luminance range of 9-10 orders of magnitude. Which of the following IS NOT a mechanism involved in this?
1. pupil dilation and constriction
2. rods and cones have different luminance sensitivities
3. center surround receptive fields and lateral processing by horizontal and amacrine cells
4. the cornea and lens project an inverted image on the retina
5. adaptation in the phototransduction cascade in responses to light
the cornea and lens project an inverted image on the retina
The reasons why the visual system may have evolved G protein signaling for phototransduction is that G protein signaling provides ________.
1. sensitivity and selectivity
2. resolution and specificity
3. convergence and divergence
4. amplification and adaptation
5. all of these answers
amplification and adaptation
When light is increased in the center of their receptive field, some retinal ganglion cells respond with an increase in action potentials while other RGCs respond with a decrease in action potentials. Which of the following IS NOT a component of this?
1. The differences between rod and cone sensitivity and rate of response to light
2. RGCs produce baseline APs, so the frequency of APs can increase or decrease in response to light
3. On-center and Off-center RGCs exist
4. Off-center bipolar cells conserve the sign of the light response while On-bipolar cells invert the sign of the response to light
5. Vertical and lateral processing
The differences between rod and cone sensitivity and rate of response to light
Cones are responsible for all of the following EXCEPT ____.
1. high resolution vision during daylight
2. photopic vision
3. peripheral vision
4. color vision
5. high acuity vision
peripheral vision
Which of the following is NOT TRUE about retinal ganglion cells/neurons (RGCs)?
1. The majority of RGCs have center-surround receptive fields
2. RGCs receive direct inputs from photoreceptor, bipolar, horizontal and amacrine cells
3. RGCS provide the output from the retina to the thalamus, midbrain and hypothalamus
4. RGCs are sensitive to specific aspects of the visual field such as edges, color or movement
5. The majority of RGCs are called M, P or K based on which neurons/layers they transmit information to in the thalamus
RGCs receive direct inputs from photoreceptor, bipolar, horizontal and amacrine cells
Match the retinal ganglion cell/neuron with its characteristic.
M cells
P cells
K cells
IPRG cells
M cells: Less numerous, larger center surround receptive cells, are sensitive to depth and indifferent to color and rapidly adapt to stimulus
P cells: Most numerous, smaller center surround receptive cells, are sensitive to color and shape
K: very large center-only receptive cells that are sensitive to color and indifferent to shape.
IPRG cells: express melanopsin and synapse on neurons in the hypothalamus and midbrain.
Which of the following is NOT TRUE about the output from the retina? Axons project DIRECTLY to the ____.
1. tectum/superior colliculus, which is involved in controlling eye movements
2. frontal eye fields, which is involved in saccades
3. SCN of the hypothalamus, which is involved in circadian rhythm
4. lateral geniculate nucleus of the thalamus, which is involved in image information
5. pretectum, which is involved in constriction of the pupils
frontal eye fields, which is involved in saccades
Which of the following is NOT TRUE about the lateral geniculate nucleus (LGN) of the thalamus?
1. Each LGN receives information from only the left or right visual field
2. The LGN of the thalamus integrates visual information with somatosensory and auditory information and plays a key role in perception
3. LGN neurons that transmit information to the primary visual cortex are glutamatergic projection neurons
4. LGN neurons send axons that form the optic radiation
5. LGN neurons project axons to the midbrain, hypothalamus and primary visual cortex
LGN neurons project axons to the midbrain, hypothalamus and primary visual cortex
Based on their properties, one can predict that in the LGN, the cells in the _______ layers are more involved in motion and movement detection, while the cells in the ______ layers are more involved in color and shape detection.
1. parvocellular,koniocellular
2. magnocellular, parvocellular
3. parvocellular, magnocellular
4. koniocellular, magnocellular
magnocellular, parvocellular
Which of the following is NOT TRUE about the primary visual cortex (V1)?
1. V1 receives inputs from magnocellular, parvocellular and konicellular pathways in the LGN
2. V1 is called the striate cortex and is located at the back of the occipital lobe
3. V1 involves parallel processing and some integration of information in Layers II/III
4. V1 transmits information to V2, MT, the superior colliculus and back to the thalamus
5. VI receives inputs from the LGN of the thalamus, frontal eye fields and hypothalamus
VI receives inputs from the LGN of the thalamus, frontal eye fields and hypothalamus
Visual information transmitted to the primary visual cortex (V1) is initially transmitted to _____.
1. layers V/VI
2. all of these answers
3. layers IV and II/III
4. layers II/III
layers IV and II/III
Which of the following is NOT TRUE about neurons in V1?
1. simple cells have center-surround receptive fields
2. simple cells and complex cells are located in Layer II/III
3. orientation sensitive neurons are involved in object recognition
4. direction sensitive neurons are involved in object movement
5. complex cells are constructed from inputs of several like-oriented simple cells
simple cells and complex cells are located in Layer II/III
Similar to how the mouth and hands are overrepresented (compared to other parts of the body) in S1 of the somatosensory cortex, the ______of/in the visual field is overrepresented (compared to _____), in V1 of the visual cortex.
1. movement of objects, object recognition
2. contrast, the luminance
3. shape of objects, their color
4. center, the periphery
5.all of these answers
center, the periphery
The _______stream is also known as the “where-how” pathway that provides visual information for the analysis of visual motion and the visual control of action.
1. posterior
2. dorsal
3. superior
4. ventral
5. anterior
dorsal
The stream in the question above projects directly toward the ____ lobe.
1.frontal
2. temporal
3. parietal
4. occipital
5. insular
parietal
The stream in questions above originates with the ______ RGC/LGN pathway.
M, magnocellular
Based on the information you've learned about motor and sensory pathways, what is the most likely brain region where the stream in question above directly transmits and integrates information?
1. all of these answers
2. insula and cingulate cortex
3. frontal eye fields
4. posterior parietal cortex
5. somatosensory cortex
posterior parietal cortex
The _____ stream is also known as the “what” pathway that provides visual information about the perception of the visual world and the recognition of objects.
1.posterior
2. dorsal
3. inferior
4. ventral
5. lateral
ventral
The stream in question above projects directly toward the _____ lobe.
1. parietal
2. frontal
3. occipital
4. temporal
5. insular
temporal
This stream in the question above originates with the ______ RGC/LGN pathway.
P, parvocellular
Even though the two streams process different aspects of the visual world, they converge on ______.
1. the prefrontal cortex and motor cortex
2. the fusiform face area
3. all of these answers
4. MT and IT
5. the posterior parietal cortex
the prefrontal cortex and motor cortex
Which of the following IS NOT TRUE about color vision ?
1. It involves photoreceptors located both inside and outside the fovea
2. It involves a comparison to two different wavelengths of light
3. It involves P and K types of retinal ganglion cells
4. It requires the responses from at least two types of cone photoreceptors
5. It involves only cone photoreceptors
It involves a comparison to two different wavelengths of light
Damage to the fusiform face area leads to ____.
1. prosopagnosia
2. all of these answers
3. synesthesia
4. hemispatial neglect
5. aphantasia
prosopagnosia