Chapter 3: Neural Processing

Question 1

Lateral inhibition

Answer 1

Inhibition that is transmitted across the retina

Question 2

Chevreul illusion (staircase illusion)

Answer 2

The 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

Describe the experiment that demonstrated the effect of lateral inhibition in the Limulus (Test Yourself 3.1)

Answer 4

Used the crab to demonstrate how lateral inhibition can affect the response of neurons in a circuit

Illuminating of the neighbouring receptors of at B inhibited the firing caused by stimulation of receptor A

The decrease in the firing of receptor A is caused by lateral inhibition that is transmitted from B to A across the limulus eye by the fibers if the lateral plexus

Question 5

Receptive field

Answer 5

The area that caused the neuron to fire the nerve fiber’s (a ganglion cell, not a receptor)

The region of the retina that must receive illumination in order to obtain a response in any given fiber

The area of the retina that, when stimulated, influences the firing of the neurons

Question 6

Excitatory area

Answer 6

Presenting a spot of light to the center increases firing

Question 7

Inhibitory area

Answer 7

Presenting a spot of light to the center decreases firing

Question 8

Inhibitory-center, excitatory surround receptive field

Answer 8

Responds with inhibition when the center is stimulated and excitation when the surround is stimulated

Question 9

Excitatory-center, inhibitory-surround receptive field

Answer 9

Responds with excitation when the center is stimulated and inhibtion when the surround is stimulated

Question 10

Excitatory-center, inhibitory-surround receptive field

Answer 10

Responds with excitation when the center is stimulated and inhibition when the surround is stimulated

Question 11

Important Rule

Answer 11

The receptive field is always on the receptor surface because this is where the stimuli are received

Question 12

Lateral geniculate nucleus

Answer 12

(LGN) signals leaving the eye in the optic nerve travel here

Question 13

The occipital lobe is the Visual receiving area

Answer 13

The place where signals from the retina and LGN first reach the cortex

Question 14

Superior colliculus

Answer 14

Plays an important role in controlling the movements of the eye

Question 15

Striate cortex

Answer 15

The visual receiving area
- called this because it has a striped appearance when viewed in cross sectional or area V1 to indicate that it is the first visual area in the cortex

Question 16

Simple cortical cells

Answer 16

Cells with side-by-side receptive fields

Excitatory and inhibitory area arranged side by side. Responds best top bars of a particular orientation

Question 17

Complex cells

Answer 17

Respond best to bars of a particular orientation.
-only respond when a correctly orientated bar of light moves across the entire receptive field
(not stimulated by stationary flashes of light)

Question 18

End stopped cells

Answer 18

Fire to moving lines of a Specific length or to moving corners or angles (responded best to a medium sized corner that is moving upward)

Question 19

Page 15 of Chapter 3

Answer 19

Types of cells and their characteristics of receptive field

Question 20

Selective adaptation

Answer 20

Firing causes neurons to eventually become fatigued or adapt.
This adaption cases two physiological effects:
1) The neurons firing rate decreases
2) The neuron fires less when the stimulus is immediately presented again

Question 21

Contrast threshold

Answer 21

The minimum intensity difference between two adjacent bars that can just be detected

Question 22

Inferotemporal cortex

Answer 22

When removed in monkeys, they could not tell the difference in objects

Question 23

Sensory coding

Answer 23

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

Question 24

Specificity coding

Answer 24

The idea that an object could be represented by the firing of a specialized neuron that responds only to that object

Question 25

Population coding

Answer 25

The representation of a particular object by the pattern of firing of a large number of neurons

Question 26

Sparse coding

Answer 26

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

Question 27

Contextual modulation

Answer 27

The effect of stimulating outside the receptive field

Question 28

Hartline noted that the receptive fields of many different nerve fibers overlap

Answer 28

This means that shining light on a particular point on the retina activates many ganglions cell fibers

Question 29

The optic nerve which leaves the back of the eye, contains about

Answer 29

Contains about 1 million optic nerve fibers in the human

Question 30

Cats receptive field are arranged in

Answer 30

a center-surround organization, in which the area in the ‘center’ of the receptive field responds differently to light than the area in the surround of the receptive field

Question 31

Center-surround antagonism

Answer 31

Small spot of light presented to the excitatory center of the receptive field causes a small increase in the rate of nerve firing (increasing that light size increases the response, but do not go into the inhibition zone)

Question 32

Selective rearing

Answer 32

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

Question 33

Neural plasticity or experience-dependant plasticity

Answer 33

The idea that the response properties of a neuron can be shaped by perceptual experience (having an animal that grew up in an environment with only vertical lines will lead that animals visual system having neurons that respond predominately to verticals)

Question 34

Spatial submasion (summation?)

Answer 34

If convergence is high, then spatial summation is high

Spatial summation means that the process of something over space because of convergence. One ganglion cell where that receptive field for that ganglion cell is 120 rods, so it summates over that field.

Question 35

Rods and cones synapse with cells

Answer 35

do not bother with horizontal or amacrine cells

Rods and cones synapse with bipolar cells, which then synapse with ganglion cells