Kap 6. Vision

Question 1

sensation

Answer 1

sensation involves the cells of the nervous system that are specialized to detect stimuli from the enviroment

Question 2

perception

Answer 2

perception is the concious experience and interpretation of information from the senses that involves neurons in the central nervous system

Question 3

tre dimensjoner som bestemmer persipert farge av lys

Answer 3

hue, saturation & brightness

Question 4

sensory receptors

Answer 4

specialized neurons that detect a variety of physiological events

Question 5

sensory transduction

Answer 5

stimuli that are detected by sensory receptors alter the membrane potentials of the cell

Question 6

receptor potentials

Answer 6

change in membrane potential that cause electrical changes is called receptor potentials

Question 7

the retina

Answer 7

inner lining of the eye. part of the brain (CNS)

Question 8

layers of the retina

Answer 8

photoreceptive layer, bipolar layer and ganglion layer. light has to pass through the ganglion and bipolar before it hits the photoreceptive layer.

Question 9

photoreceptor cells

Answer 9

cones and rods

Photoreceptors are active in the dark and become hyperpolarized when they absorb photons.

When photoreceptors are hyperpolarized they release less glutamate onto bipolar cells.

Question 10

optic disk

Answer 10

located in the back of the eye, where the axons that convey visual information gather together and leave the eye through the optic nerve

Question 11

horizontal and amacrine cells

Answer 11

both of which transmit information in a direction parallel to the surface of the retina and combine messages from adjacent photoreceptors

Question 12

transduction

Answer 12

the process where stimuli is converted into a change in membrane potential

Question 13

How long wavelength of electromagnetic radiation is visible to us?

Answer 13

a wavelength of between 380 and 760 nanometer

(nm = one-billionth of a meter)

Question 14

Speed of light

Answer 14

ca. 300 000 km pr. sec

Question 15

Hue

Answer 15

= Fargetone

Question 16

Saturation

Answer 16

= Metning

the relative purtity of the light that is being perceived

Question 17

Brigthness

Question 18

“sclera”

feil

Answer 18

hold the eyes in place and move it
Its six extraocular muscles attached to the tough, white outer coat of the eye
Its also “opaque” and does not permit entry of light into the eye

Question 19

cornea

Answer 19

outer layer at the front of the eye
transparent and

Question 20

Fovea

Answer 20

central region of the retina
- our most acute vision
- contains only cones

Question 21

cone

Answer 21

hues, sensitive to moderate to high levels of light. found in the central retina (fovea). gives excellent acuity

Question 22

rods

Answer 22

sensitive to low levels of light, monochromatic, most prevalent in perepherial retina, gives poor acuity

Question 23

The eye have two types of eye movement :

Answer 23

Vergence movement (Vergens): Øyebevegelser der øynene beveger seg mot hverandre (konvergens) eller fra hverandre (divergens) for å fokusere på objekter på ulike avstander.

saccadic movements: Raske, hoppende bevegelser øynene gjør for å skifte fokus fra ett punkt til et annet.

Pursuit movements (følgning): Glatte øyebevegelser som brukes for å følge et objekt som beveger seg.

Question 24

Vergence movements

Answer 24

cooperative movements that keep both eyes fixed on the same target

Question 25

saccadic movements

Answer 25

speed of eye movement

Question 26

pursuit movements

Answer 26

“makes eye move slower”

Question 27

Trichromatic theory (three color) -

Answer 27

suggested that the eye contained three receptors for different colors of light.

Question 28

Opponent color theory

Answer 28

– suggested that light is represented as opponent colors, i.e. red versus green and yellow versus blue.

Question 29

Visual agnosia

Damage to areas of extrastriate cortex in humans can result in a number of problems like …..

Answer 29

-Inability to identify common objects despite normal visual acuity.

-Some still have normal reading ability so reading in different brain area than object perception.

-Still able to recognise objects by touch.

• Normally damage to ventral visual stream.

Question 30

Prosopagnosia

Answer 30

• Inability to recognize faces.
• Studies from people with brain damage and functional imaging suggest fusiform face area is essential.
• Some people have prosopagnosia with no obvious brain damage – may be due to difference in brain connectivity.

Question 31

extrastriate body area (EBA).

Answer 31

region in ventral stream for body recognition

Question 32

Monocular (one eye) information includes:

Answer 32

Perspective
Relative retinal size
Loss of detail through haze
Relative movement as we move our heads

Question 33

Binocular information gives us …

Answer 33

stereoscopic vision, very important for fine movements of hands and fingers

Question 34

Akinetopsia (disease)

Answer 34

• can be produced by bilateral damage to V5.
• Patients experience the world as a series of still frames.