Chapter 52: The Eye: III. Central Neurophysiology of Vision

Question 1

These are fibers from the thalamus that pass via the optic radiation to the primary visual cortex

Answer 1

geniculocalcarine fibers

Question 2

Area of the brain that controls the rapid directional movements of the two eyes

Answer 2

superior colliculus

Question 3

Layers of the dorsal lateral geniculate nucleus that receive signals from the lateral half of the ipsilateral retina

Answer 3

Layers II, III, V

Question 4

Layers of the dorsal lateral geniculate nucleus that receive signals from the medial half of the retina of the opposite eye

Answer 4

Layers I, IV, VI

Question 5

The lateral geniculate nucleus receives gating control signals from two major sources:

Answer 5

corticofugal fibers

reticular areas of the mesencephalon

Question 6

What are the magnocellular layers of the LGB?

Answer 6

Layers I and II

Question 7

What are the parvocellular layers of the LGB?

Answer 7

Layers III and VI

Question 8

These are cells of the LGB that transmit color and convey accurate point to point spatial information, but at only a moderate velocity of conduction rather than at high velocity.

Answer 8

P retinal ganglion cells

Question 9

A person with CNS syphilis can manifest with what type of pupil?

Answer 9

Argyll Robertson Pupils

A pupil that fails to respond to light but does respond to accommodation and is also very small (an Argyll Robertson pupil) is an important diagnostic sign of a central nervous system disease such as syphilis.

Question 10

What are the 4 manifestations of Horner Syndrome?

Answer 10

miosis, ptosis, anhidrosis and persistent vasodilation of the blood vessels in ipsilateral face and neck

Question 11

In all perimetry charts, this caused by lack of rods and cones in the retina over the optic disc is found about 15 degrees lateral to the central point of vision

Answer 11

blind spot

Question 12

Occasionally, blind spots are found in portions of the field of vision other than the optic disc area. Such blind spots, called ________, are frequently caused by damage to the optic nerve resulting from glaucoma (too much fluid pressure in the eyeball), allergic reactions in the retina, or toxic conditions such as lead poisoning or excessive use of tobacco.

Answer 12

scotomata

Question 13

In this disease, portions of the retina degenerate, and excessive melanin pigment is deposited in the degenerated areas. This usually causes blindness in the peripheral field of vision first and then gradually encroaches on the central areas.

Answer 13

Retinitis pigmentosa

Question 14

These ocular muscles function mainly to rotate the eyeballs to keep the visual fields in the upright position.

Answer 14

obliques

Question 15

Interconnections among the brain stem nuclei via the nerve tract called the _________ allows each of the three sets of muscles to each eye to be reciprocally innervated so that one muscle of the pair relaxes while the other contracts.

Answer 15

medial longitudinal fasciculus.

Question 16

Strong signals are also transmitted from the
body’s equilibrium control centers in the brain stem into the oculomotor system, from the ________ nuclei via the medial longitudinal fasciculus.

Answer 16

vestibular nuclei

Question 17

This mechanism allows a person to move the eyes voluntarily to find the object on which he or she wants to fix the vision.

Answer 17

voluntary fixation mechanism

Question 18

This mechanism holds the eyes firmly on the object once it has been found.

Answer 18

involuntary fixation mechanism

Question 19

The mechanism that causes the eyes to “lock” on the object of attention once it is found is controlled by which part of the cortex?

Answer 19

secondary visual areas in the occipital cortex

Question 20

The voluntary fixation movements are controlled by a cortical field located bilaterally in which part of the cortex?

Answer 20

premotor area of the frontal lobe

Question 21

Analysis of three-dimensional position, gross form, and motion of objects occurs in which secondary visual area?

Answer 21

posterior midtemporal area and occipitoparietal area

Question 22

Analysis of visual detail and color occurs in which secondary visual area?

Answer 22

interior, ventral and medial regions of occipital and temporal cortex

Question 23

The signals transmitted in this major pathway for visual analysis are mainly from the large M optic nerve fibers of the retinal M ganglion cells, transmitting rapid signals but depicting only black and white with no color.

Answer 23

position-form-motion pathway

Question 24

The signals transmitted in this major pathway for visual analysis is concerned with such visual feats as recognizing letters, reading, determining the texture of surfaces, determining detailed colors of objects, and deciphering from all this information what the object is and what it means.

Answer 24

Pathway for the analysis of visual detail

Question 25

These Cells Detect Line Orientation When a Line Is Displaced Laterally or Vertically in the Visual Field.

Answer 25

complex cells

Question 26

Which cells in layer IV of the primary visual cortex detect orientation of lines and borders?

Answer 26

simple cells

Question 27

This condition occurs

Question 28

This is an alpha-adrenergic agonist used to test for Horner’s syndrome as it can cause extensive dilation of the hypersensitive, denervated pupillary dilator muscle (as denervation of this muscle increases the number of its α-1 receptors)

Answer 28

apraclonidine