Vision

Question 1

What is light?

Answer 1

Narrow range of electromagnetic spectrum; part of the spectrum that is visible to the human eye

Question 2

What are cones?

Answer 2

Type of photoreceptor; good for daytime vision, higher resolution visual acuity

Question 3

Where are cones found?

Answer 3

Highly concentrated in the fovea

Question 4

What are rods?

Answer 4

Type of photoreceptor; good for seeing form/outline and mediating vision in dim illumination

Question 5

What is the optic disk?

Answer 5

where ganglion cell axon exits the eye; there are no photoreceptors here and thus creates a blind spot

Question 6

Where does ipsilateral visual information cross?

Answer 6

the optic chasm; neurons carrying info from nasal side cross to contralateral hemisphere

Question 7

How many pathways occur from the optic chiasm?

Answer 7

Three; 1 pathway - superior colliculus, 2 pathway - hypothalamus; or lateral geniculate

Question 8

True or false: Contralateral visual information crosses over to opposite hemisphere

Answer 8

False; contralateral info stays on the same side (e.g., left visual field processed in right eye)

Question 9

What is the lateral geniculate body?

Answer 9

Nucleus of thalamus; comprised of 6 layers plus sublayer: magnocellular, parvocellular, and koniocellular

Question 10

What are magnocellular layers?

Answer 10

Make up 1st and 2nd layer of the lateral geniculate body (LGN); they receive input from rods and are sensitive to light; they are NOT sensitive to color

Question 11

What are parvocellular layers?

Answer 11

Make up 3rd-6th layers of LGN; they receive input from cones (so…color!)

Question 12

What is the koniocellular pathway?

Answer 12

Found between each mangocellular and parvocellular pathway; it also receives info from cones

Question 13

What do layers of the LGN do?

Answer 13

Each layer projects to a specific area in the striate (visual) cortex; segregation of the information is preserved in the cortex

Question 14

Where is the central visual field processed?

Answer 14

Posterior primary visual cortex

Question 15

Where is peripheral visual field processed?

Answer 15

Anterior primary visual cortex

Question 16

True or false: the visual field is disproportionately represented

Answer 16

True; 25% of the primary cortex processes info from the fovea (but the fovea is a very small portion of our visual field)

Question 17

The primary visual cortex is also know as…?

Answer 17

The striate cortex; V1

Question 18

How does V1 process information?

Answer 18

Approx. 2,500 modules process information for color, form, and movement in discrete areas

Question 19

What is subjective blindness?

Answer 19

When an individual still has visually-mediated behaviors; it is related to the pathway 1 where information is processed via the superior colliculus

Question 20

What is “the where system”?

Answer 20

The dorsal stream of the association visual cortex; perceives location and mediation of one’s own movement

Question 21

What is “the what system”?

Answer 21

The ventral stream of the association visual cortex; perceives objects/color (e.g., the identity of things, what objects are)

Question 22

Where is the dorsal stream located and where does its input come from?

Answer 22

Located in parietal lobe; input mostly from magnocellular pathways

Question 23

Where is the ventral stream located and where does its input come from?

Answer 23

Located in temporal lobe; input equally from magnocellular and parvo + some koinocellular

Question 24

What is visual agnosia?

Answer 24

A sensory impairment where visual acuity remains intact but the person cannot identify objects by sight

Question 25

What is apperceptive visual agnosia?

Answer 25

A perceptual impairment and visual agnosia; bilateral lateral occipital damage; individuals cannot copy simple drawings and cannot recognize objects well

Question 26

What is associative visual agnosia?

Answer 26

Perception is intact with visual agnosia; anterior ventral stream damage; individuals can copy drawings

Question 27

What is prosopagnosia?

Answer 27

Impaired ability to recognize familiarize faces and learn new faces