neural foundations

Question 1

the eye

Answer 1

• light is focused by the cornea/lens onto the fovea

- light has to pass through fibers forming optic nerve and other cells before reacing the photo receptors (rods/cones)

Question 2

focusing light in the eye

Answer 2

cornea- fixed
lens- adjustable
accomodation is the change in shape of lens due to ciliary muscles

Question 3

hyperopia

Answer 3

image is formed behind retina- farsightedness

Question 4

myopia

Answer 4

image is formed infront of retina- nearsightedness

Question 5

blind spot

Answer 5

large hole in the sheet of photo receptors because all fibers of optic nerve exit here

Question 6

distribution of rods/cones

Answer 6

cones greatest at fovea

rods greatest away from fovea

Question 7

acuity in peripheral vision example

Answer 7

participants are unaware that 90% of the image is blurry except where they are looking because they can only see the details where they are looking and not in periphery

Question 8

gaze contingent rendering example

Answer 8

dont have to render an entire image clear- just where the participant is looking

Question 9

order of cells (top to bottom)

Answer 9

photoreceptors
horizontal cell
bipolar cells
amacrine cells
ganglion cells

Question 10

light sensitive visual pigments

Answer 10

special molecules in the class of opsins - in outer segment of cones
- photon of light comes in and bumps into retinal, energizes the system and changes how molecule is shaped (isomerization)

Question 11

different types of visual pigements

Answer 11

all have the same shape but specific amino acid sequences are different
3 types of cones (SML) detect different wavelengths best

Question 12

molecular cascade

Answer 12

change in shape of single molecule (visual pigment) that leads to affect more molecules until signal is large enough to make a difference in NS
ex. a single photon absorbed by retinal leads to an amplified effect involving millions of molecules

Question 13

what happens if a photoreceptor detects light

Answer 13

it releases less NT

- always firing glutamate at baseline level and when detects light the cone reduces amount of NT

Question 14

dark adaptation curve

Answer 14

cones- good at operating in daylight

rods- more sensitive in lowlight situation

Question 15

light adaptation curve

Answer 15

ability of rod/cone to detect light in an environment

Question 16

spectral sensitivity

Answer 16

most sensitive area in the spectrum
inverse of threshold curve
- rod vision is better towards green/blue and cone towards yellow

Question 17

sensitivity

Answer 17

• how faint of a signal we can detect
• low acuity because cannot distinguish difference between inputs
  GREATER SENSITIVITY AT HIGH CONVERGENCE

Question 18

acuity

Answer 18

• how fine the details are
  can detect where something is occuring
  GREATER ACUITY AT LOW CONVERGANCE

Question 19

PSPs

Answer 19

originate at synapse, graded, depends on NT and receptors- vary in size, sign and speed
electrotonically propogate to axon hillock
excitatory- increase in positive charge (depol)
inhibitory- increase in negative charge (hyperpol)

Question 20

center surround receptive field

Answer 20

excitatory center and inhibitory surround or vice versa
receptive fields are larger than just 1 individual receptor cell
may reduce acuity (convergance) but boosts sensitivity

Question 21

center surround vision

Answer 21

like to be on the edge of light and dark
emphasize edges
- can build orientation feature detectors from these