Chapter 4

Question 1

What is a retinotopic map?

Answer 1

Map of the retina on the cortex

More space is the cortex is allocated to locations near the fovea then to locations in peripheral

Question 2

What is it called when the brain gives images in the fovea more space in the brain?

Answer 2

Cortical magnification factor

Question 3

What is the cortex organized in?

Answer 3

Columns

Question 4

Explain how the striate cortex is organized into location columns

Answer 4

A column in the visual cortex that contains neurons with the same receptive field locations on the retina.

Basically, each receptive field overlaps, but goes to separate parts in the brain

Question 5

It was concluded that the cortex is also divided into orientation columns, what are these?

Answer 5

Each column in the brain contain cells that respond best to a particular orientation. (Ex, vertical tree, sideways road)

Question 6

How long is each column?

Answer 6

1mm

Question 7

What is a hyper column?

Answer 7

Unit that combines: location, orientation, and ocular dominance

They serve a specific area on the retina

Question 8

What is tiling?

Answer 8

The adjacent (and often overlapping) location columns working together to cover the entire visual field (similar to covering a floor with tiles)

Question 9

What is the extrasriate cortex?

Answer 9

Collective term for visual areas in the occipital lobe and beyond (V2, V3, V4, and V 5)

Question 10

What is Ablation /lesioning ?

Answer 10

Removal of an area of the brain. This is usually done in experiments on animals to determine the function of a particular area.

Question 11

What happened in the object discrimination problem ?

Answer 11

Shown an object that had nothing in it. Then presented with two objects, they should select the new one immediately to get the treat.

Question 12

What is the landmark discrimination problem?

Answer 12

Choosing the object closest to the location

Question 13

What happens to the object discrimination problem when part of temporal lobe is abaltioned ?

Answer 13

This damages the ability to determine an objects identity. Called the what pathway.

Also ventral pathway

Question 14

What happens to the landmark discrimination problem when part of the parietal lobe is removed?

Answer 14

This causes difficulty in determining the objects location. Called the where pathway

Also called the dorsal pathway

Question 15

There is another theory on what the dorsal stream (where) also does, what is it?

Answer 15

It also provides information about how to direct action with regard to a stimulus.

Ex. When a monkey looks at and object

AND when it reaches to the objects

Question 16

What is double dissociations?

Answer 16

Have brain dmg in two people
One: can see object a but not b

Two: can see object b but not a

Question 17

Patient DF and orientation

Answer 17

Damage to ventral pathway and could not determine orientation of letters to fit them in slots.

This prompted the idea that where pathway could also be called how or action pathway.

Question 18

What is the info-temporal (IT) cortex?

Answer 18

Area of the brain outside V1 (striate cortex) that does object perception and facial recognition

Also continues through the what stream

Question 19

What is the hippocampus?

Answer 19

Place for forming and storing memories

Question 20

What is contextual modulation?

Answer 20

Change in response to a stimulus presented within a neurons receptive field caused by stimulation outside of the receptive field.

Question 21

What is the optic chiasm?

Answer 21

And x shaped bundle of fibres on the underside of the brain, where nerve fibres are activiated by stimulation of one side of the visual field cross over to opposite side of the brain

Question 22

What’s the lateral geniculate nucleus (LGN)?

Answer 22

Where 90 percent of signals from retina go.

It’s the nucleus in the thalamus that receives inputs from the optic nerve and, in turn, communicates with the cortical receiving area for vision.

Question 23

What is the superior colliculus?

Answer 23

The area in the brain that is involved in controlling eye movements and other visual behaviours. This area receives about 10 percent of the ganglion cell fibres that leave the eye in the optic nerve.

Question 24

Where does the LGN receive signals from?

Answer 24

More signals from cortex then from the retina.

Takes signals from cortex and retina, puts them together and sends to cortex for more processing

Question 25

What is the visual receiving area of the brain (occipital lobe)?

Answer 25

Place where signals from retina and LGN first hit cortex.

Also called striate cortex, cuz striped appearance. Or area V1

Question 26

What are simple cortical cells?

Answer 26

A neuron in the visual cortex that responds best to bars of a particular orientation

Question 27

What is the orientation tuning curve?

Answer 27

A function relating the firing rate of a neuron to the orientation of the stimulus.

Question 28

What are complex cells?

Answer 28

A neuron in the visual cortex that responds best to moving bars with a particular orientation.

Question 29

What are end stopped cells?

Answer 29

A cortical neuron that responds best to lines of a specific length that are moving in a particular direction

Question 30

What are feature detectors?

Answer 30

A neuron that responds selectively to a specific feature of the stimulus such as orientation or direction of motion

Question 31

What is selective adaptation?

Answer 31

A procedure in which a person or animal is selectively exposed to one stimulus, and the effect of this exposure is assessed by testing with a wide range of stimuli.

Typically, sensitivity to the exposed stimulus is decreased

Question 32

What are the two effects of selective adaptation?

Answer 32

1. Neurons firing rate decreases
2. Neuron fires less when that stimulus is immediately presented again

Question 33

What is a contrast threshold?

Answer 33

Intensity difference between two areas that can just barely be seen. This is often measured using gratings with alternating light and dark bars

Question 34

What is selective rearing?

Answer 34

Animals are reared in special environments.

Ex. Kittens with vertical lines

Question 35

What is neural plasticity in relation to selective rearing?

Answer 35

The capacity of the nervous system to change in response to experience. Examples are how early visual experience can change the orientation selectivity of neurons in the visual cortex and how tactile experience can change the sizes of areas in the cortex that represent different parts of the body