Chapter 10: The Central Visual System

Question 1

central visual system

Answer 1

pathway serving conscious visual perception originates in the retina. Progresses to lateral geniculate nucleus, primary visual cortex, and higher order visual areas in occipital, temporal and parietal lobes.

Question 2

retinofugal projection

Answer 2

the neural pathway that leaves the eye, beginning with the optic nerve.

Question 3

decussation

Answer 3

the crossing of a fiber bundle from one side of the brain to the other.

Question 4

optic nerves

Answer 4

exit the left and right eyes at the optic disks, travel through the fatty tissue behind the eyes in their bony orbits, then pass through holes in the floor of the skull.

Question 5

optic chiasm

Answer 5

lies at the base of the brain, just anterior to where the pituitary gland dangles down from.

Question 6

optic tracts

Answer 6

axons of the retinofugal projections form this which runs just under the pia along the lateral surface of the diencephalon.

Question 7

left visual hemifield

Answer 7

objects appearing to the left of the midline are in the left visual hemifield.

Question 8

right visual hemifield

Answer 8

objects appearing to the right of the midline are in the right visual hemifield

Question 9

binocular visual field

Answer 9

by looking straight ahead with both eyes open and then alternately closing one eye and then the other, you will see that the central portion of both visual hemifields is viewed by both retinas.

Question 10

lateral geniculate nucleus

Answer 10

most optic tract axons innervate the lateral geniculate nucleus of the dorsal thalamus. Neurons in the LGN give rise to axons that project to the primary visual cortex. Arranged into 6 distinct layers of cells.

Question 11

optic radiation

Answer 11

projection from the LGN to the cortex.

Question 12

targets of the optic tract

Answer 12

lesions anywhere in the retinofugal projection from the eye to the LGN to the visual cortex cause blindness in part or all of the visual field. Visual field deficits from lesions in the retinofugal projection.

Question 13

superior colliculus

Answer 13

projections to a part of the midbrain tectum called the superior colliculus control saccadic eye movements.

Question 14

hypothalamus

Answer 14

projections to part of the hypothalamus play an important role in synchronizing a variety of biological rhythms, including sleep and wakefulness.

Question 15

pretectum

Answer 15

projections to part of the midbrain called the pretectum, control the size of the pupil and certain types of eye movement.

Question 16

primary visual cortex

Answer 16

Brodmann’s area 17, located in occipital lobe of the primate brain. Also called V1 and the striate cortex.

Question 17

retinotopic

Answer 17

neurons organized in V1 like a map of the retina, so they receive input from specific regions of retina.

Question 18

V2/V3

Answer 18

further processing; combination of signals

Question 19

V4

Answer 19

color interpretation

Question 20

V5/MT

Answer 20

motion detection; direction processing. Neurons in area MT respond briskly if something moves relative to the background but show little response if the object and the background both move in the same direction and speed. MT neurons enable you to distinguish between the result of eye movements and the results of object movements.

Question 21

motion blindness

Answer 21

an impaired ability to perceive movement after damage to area MT and surrounding areas

Question 22

prospagnosia

Answer 22

inability to recognize faces, can result from damage to the fusiform gyrus, failure of the gyrus to develop fully, having small fusiform gyrus or few connections between the fusiform and occipital cortex.

Question 23

dorsal stream

Answer 23

where/how, analysis of visual motion and the visual control of action. If damaged, can see objects but don’t integrate their vision with their arm and leg movements, cannot accurately reach out and grab an object.

Question 24

ventral stream

Answer 24

what, perception of the visual world and the recognition of objects. If damaged, cannot name objects, recognize faces, or distinguish a square from a rectangle. Can use vision to guide actions.