Visual system (kpl 9-10)

Susan fell down the staircase and injured her head, causing a transection of the left optic nerve. What is the consequence of this lesion? Choose the correct option. A. Blindness in the left eye B. Blindness in the right visual field C. Blindness in the right eye D. Blindness in the left visual field

A. Blindness in the left eye

Which of the following is the most likely basis of visual perception? Choose the correct option. A. Concerted activity of many neurons throughout the visual pathways B. Decussation at the optic chiasm, projecting the left visual field to the right brain and the right field to the left brain C. Binocular neurons in striate cortex D. Hierarchical organization of visual receptive fields culminating in highly specialized cells such as grandmother cells

A. Concerted activity of many neurons throughout the visual pathways

Why does the fovea appear like a pit in a cross-sectional view of the retinal? Choose the correct option. A. Because of the presence of other cells in the fovea that might scatter light B. Because of the lateral displacement of cells above the photoreceptors in the fovea C. Because photoreceptors are smaller in the fovea D. Because of a low ratio of photoreceptors to ganglion cells in the fovea

B. Because of the lateral displacement of cells above the photoreceptors in the fovea

Why there is no sensation of light at the optic disk? Choose the correct option. A. Because the optic disk is a theoretical construct B. Because there are no photoreceptors in the optic disk C. Because of the presence of the vitreous humor D. Because optic nerve fibers exit the retina at this point

B. Because there are no photoreceptors in the optic disk

Choose the true statement A. The LGN does not receive efferent information from the eyes or the primary visual cortex (V1) B. LGN receives more input from the primary visual cortex (V1) than the eyes C. LGN receives more input from the eyes than from the primary visual cortex (V1) D. LGN receives approximately similar amount of efferent information from the eyes and the primary visual cortex (V1)

B. LGN receives more input from the primary visual cortex (V1) than the eyes

Which layer contains the light-sensitive elements of the retina? Choose the correct option. A. Ganglion cell layer B. Photoreceptor layer C. Outer plexiform layer D. Inner nuclear layer

B. Photoreceptor layer

Which of the following is the common characteristic in the receptive fields in the ganglion cells of the retina, the LGN, and striate cortex neurons in layer IVC? Choose the correct option. A. Optimal orientation of a bar of light B. Radial column of cells from pia to white matter C. Center surround D. Elongated bar of light moving across the receptive field

C. Center surround

Which cells in the retina have axons that leave the retina? Choose the correct option. A. Photoreceptors B. Photoreceptors, bipolar cells, and ganglion cells C. Ganglion cells D. Bipolar cells

C. Ganglion cells

Which of the following is an example of parallel processing in the central visual system? Choose the correct option. A. Regardless of any brain structure that might be destroyed, other structures will always ensure the continuity of vision. B. Streams of information from the ON-center ganglion cells depend on the information from the OFF-center ganglion cells in each retina. C. Simultaneous input from two eyes provides the central visual system with information about depth, the distance of an object from the observer. D. M- and P-type retinal ganglion cells have different receptive field properties, and their information becomes unified in the lateral geniculate.

C. Simultaneous input from two eyes provides the central visual system with information about depth, the distance of an object from the observer.

Receptive fields of visually responsive neurons A. have a center-surround organization B. modulate the responses of retinal ganglion cells C. vary in shape and size depending on how high in the cortical hierarchy the neuron is located. D. are located in cortical layer 4

C. vary in shape and size depending on how high in the cortical hierarchy the neuron is located.

Which of the following is the function of direction-selective striate cortex neurons? Choose the correct option. A. Analysis of object shape B. Analysis of object meaning C. Analysis of object color D. Analysis of object motion

D. Analysis of object motion

What is a difference between ON-center ganglion cells and OFF-center ganglion cells? Choose the correct option. A. ON-center ganglion cells respond to stimulation of their receptive field centers with a transient burst of action potentials, whereas OFF-center ganglion cells respond with a sustained discharge. B. In an ON-center ganglion cell, the response to stimulation of the center is canceled by the response to stimulation of the surround, but this response cancellation does occur in an OFF-center ganglion cells. C. ON-center ganglion cells constitute about 90% of the ganglion cell population, whereas OFF-center ganglion cells constitute about 5% of the ganglion population. D. ON-center ganglion cells receive input from ON bipolar cells, whereas OFF-center ganglion cells receive input from OFF bipolar cells.

D. ON-center ganglion cells receive input from ON bipolar cells, whereas OFF-center ganglion cells receive input from OFF bipolar cells.

Magnocellular LGN neurons mediate information from cone photoreceptors and enable color vision. False or true?

false

The binocular visual field is the entire region of space that can be seen with both eyes fixated straight ahead. True or false?

false

The optic radiation is the projection from the LGN to the optic tract. True or false?

false

Axons that remain on the same side of the brain as they project centrally are ________________ whereas fibers that cross to the opposite side are called __________________.

ipsilateral, contralateral

The retina contains two general types of photoreceptors, these are called ____________ and ___________.

rods, cones

M, P and K layers of the LGN receive information from different types of retinal ganglion cells. True or false?

true

Ocular dominance columns are bands of cells extending through the thickness of the striate cortex. True or false?

true

We do not see retinal blood vessels because they always remain in the same position. True or false?

true