Chapter 6: More Vision Flashcards Preview

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Flashcards in Chapter 6: More Vision Deck (34):
1

Law of Specific Nerve Energies

Johannes Muller; regardless of the type of stimulus, activity in the nerve always leads to the same psychological experience.

2

Photons

packets of energy with oscillating electromagnetic fields that travel through space at 3.0e8 m/s. Brightness of a light source depends on how many photons it emits

3

Wavelength

based on the frequency of electromagnetic oscillation taking into account the speed of light. Color of a light source depends on wavelengths of the photons

4

Electromagnetic Spectrum

light makes up small portion; x-rays to radio waves

5

Choroid Coat

found behind retina; heavily pigmented to absorb scatteredlight; provides oxygen and nutrients for parts of retina; maintains photoreceptors

6

Cornea

main refractive surface of the eye; bends the light; fluid filled

7

Lens

Does bend light; provides visual accommodation; siscilary muscles contract and pull the ligament and make lens thinner, relax to make it more round

8

Visual accommodation

provides fine focus by changing thickeness

9

Presbyopia

condition in which the lens lose resiliency with age

10

Iris

radial muscle tissue which constricts or expands the size of the pupil. Determines eye color

11

Humors

provide structural and functional support for the eye

12

Aqueous Humor (fluid)

in anterior chamber. Behind the cornea, in front of the lens

13

Vitreous humor

in posterior chamber. located behind the lens; helps eye maintain shape (thicker)

14

Retina

contains the visual photoreceptors and neurons that process and transmit visual information to the brain

15

Fovea

indentation in the retina, contains only cones (point of central focus)

16

Macula

has a lot of cones, surrounds the fovea

17

Photoreceptors

hyperpolarize in response to light (depolarize in response to dark), and synapse with horizontal cells and bipolar cells (RODS AND CONES)

18

Horizontal cells

have large dendritic trees that make inhibitory contaact with many nearby photoreceptors; responsible for phenomena of lateral inhibition (no action potentials)

19

Bipolar Cells

each stimulated by a group of surrounding photoreceptors forming a receptive field. synapse with ganglion cells (no action potentials)

20

ganglion cells

each stimulated by a group of surrounding bipolar cells forming a receptive field; convergence of input through the visual pathway; axons form optic nerve

21

amacrine cells

modulate the output of bipolar cells

22

Trichromatic Theory of Color Vision

color vision is based on ratio of responses from 3 different types of cones that have peak absorption of light at different wavelengths

23

Opponent Process Theory of Color Vision

the way the information is organized in the visual system appears to be based on two opponent processes: Red vs. Green; Yellow vs. Blue

24

Psychological evidence

no reddish-green or blueish-yellow color perceptions

25

Electrophysiological evidence

Some bipolar cells, ganglion cells, LGN cells, and cortical cells have center-surround receptive fields that are organized in opponent process way

26

Retinex THeory

suggests the cortex compares information from various parts of the retina to determine the brightness and color for each area. Better explains color constancy

27

magnocellular pathway

named after the large cell bodies of the retinal ganglion cells and LGN cells of the pathway

28

Parvocellular pathway

named after the small cel bodies of the retinal ganglion cells and LGN cells of the pathway

29

Parvocellular ganglion cells

have small cell bodies, small receptive fields, are dense and near fovea

30

Magnocellular ganglion cells

large cell bodies, large receptive field, and are uniformly distributed in the retina

31

koniocellular ganglion cells

small cell bodies, mixed receptive field size, and are distributed uniformly throughout retina

32

simple cells

small receptive fields, bar or edge shaped, excitatory and inhibitory zones, spots of light can produce weak excitatory or inhibitory responses

33

complex cells

larger receptive fields, no clear cut inhibitory zones, spots of light are relatively ineffective, responds to bars of light of a specific orientation anywhere in receptive field

34

occular dominance

cells in particular column respond best to input from left eye and from right eye