Lesson 3: Neural Processing

Question 1

Where is lateral inhibition performed?

Answer 1

horizontal and amacrine cells transmit inhibitory signals across the retina

Question 2

Chevreul illusion/ staircase illusion

Answer 2

perceived light and dark bands at the borders, which are not present in the actual physical stimuli

Question 3

Mach bands

Answer 3

Light and dark bands created at fuzzy borders

Question 4

When is the Chevreul illusion decreased?

Answer 4

when the dark to light progression of the staircase pattern is
opposite to the luminance ramp

Question 5

When is the Chevreul illusion increased?

Answer 5

if the pattern progresses in the same direction as the ramp

Question 6

Limulus experiment

Answer 6

The Limulus eye is made up of hundreds of tiny structures called ommatidia, and each ommatidium has a small
lens on the eye’s surface that is located directly over a single receptor. Possible to illuminate and record from a single receptor without illuminating its neighboring receptors. A= large response, A+B = medium response, and intense B= decrease in A. Explained by lateral inhibition

Question 7

Hermann grid

Answer 7

straight lines = dark spots at the intersections
curvy lines= dark spots eliminated

Question 8

Chevreul illusion

Answer 8

four gray rectangles placed side by side, ranging from light on the left to dark on the right.

Question 9

What are the optic nerves made out of?

Answer 9

nerves, nerve fibers that are the axons of the retinal ganglion cells

Question 10

receptive field

Answer 10

“the retinal region over which a cell in the visual system can be influenced (excited or inhibited) by light”
- receptive fields of many different nerve fibers overlap

Question 11

center-surround organization (cats)

Answer 11

the area in the “center” of the receptive field responds differently to light than the area in the “surround” of the receptive field

Question 12

How are the receptive fields of a cat separated?

Answer 12

excitatory center = excitatory area, increase in firing
inhibitory surround = inhibitory area, decrease in firing

Question 13

center-surround antagonism

Answer 13

interactions between the center and surround regions of the receptive fields of photoreceptor cells in the retina

Question 14

where are the receptive fields located?

Answer 14

on receptor surfaces because that is where the stimuli are received. The retina in the case of the eye.

Question 15

Where do signals leaving the eye in the optic nerve travel to? (3)

Answer 15

lateral geniculate nucleus (LGN 90%), then the occipital lobe/striate cortex/area V1 (visual receiving area), the superior colliculus (controlling movements of the eyes 10%)

Question 16

Complex cells

Answer 16

respond only when a correctly oriented bar of light moves across the entire receptive field

Question 17

end-stopped cells

Answer 17

fire to moving lines of a specific length or to moving corners or angles

Question 18

Accidental finding

Answer 18

Hubel and Wiesel’s finding that some neurons in the cortex respond only to oriented lines and others respond best
to corners was an extremely important discovery because it
extended the idea first proposed in connection with center-surround receptive fields that neurons respond to some patterns of light and not to others

Question 19

feature detectors

Answer 19

simple, complex, and end-stopped cells

Question 20

sensory coding

Answer 20

sensory code refers to how neurons represent various characteristics of the environment.

Question 21

selective rearing

Answer 21

animal is reared in an environment that contains only certain types of stimuli, then neurons that respond to these stimuli will become more prevalent

Question 22

specificity coding

Answer 22

the object can be represented by the firing of a specialized neuron that responds only to that object

Question 23

Sparse coding

Answer 23

particular object is represented by a pattern of firing of only a small group of neurons, with the majority of neurons remaining silent