higher visual areas and cortical organisation w2

Question 1

the lateral geniculate nucleus

Answer 1

a relay centre in the thalamus for the visual pathway. It receives a major sensory input from the retina.

• have center-surround receptive fields.
• Excitatory activity in middle and inhibitory active on the surrounds (or vice versa)
• LGN regulates (sorting) neural information from the retina to the visual cortex to send to the brain

Question 2

striate cortex

Answer 2

first cortical visual area that receives input from the lateral geniculate nucleus in the thalamus.

Question 3

superior colliculus

Answer 3

receives some signals from the eye.

This structure plays an important role in controlling movements of the eyes.

Question 4

optic chiasm

Answer 4

• where the visual fields side finally transfer to the opposite side of the brain
• first structure these encounter is the lateral geniculate nucleus

Question 5

Optic nerve fibre (ganglion cell):

Answer 5

Center-surround receptive field. Responds best to small spots, but will also respond to other stimuli.

Question 6

Lateral geniculate

Answer 6

Center-surround receptive fields very similar to the receptive field of a ganglion cell.

Question 7

Simple cortical

Answer 7

Cells with these side-by-side receptive fields, Excitatory and inhibitory areas arranged side by side. Responds best to bars of a particular orientation.

Question 8

complex cortical

Answer 8

-respond only when a correctly oriented bar of light moves across the entire receptive field in combination to a particular direction of movement

Question 9

End-stopped cortical

Answer 9

Responds to corners, angles, or bars of a particular length moving in a particular direction

Question 10

orientation tuning curve

Answer 10

The relationship between orientation and firing

Question 11

feature detectors

Answer 11

fire to only specific features of the stimulus, such as orientation or direction of movement, they have been called feature detectors.

When researchers show that neurons respond to oriented lines, they are measuring relationship B: the stimulus– physiology relationship

Question 12

selective adaption

Answer 12

selective adaptation: firing causes neurons to eventually become fatigued or adapt to stimulus
- two physiological effects: (1) the neuron’s firing rate decreases, and (2) the neuron fires less when that stimulus is immediately presented again.

Question 13

contrast threshold

Answer 13

minimum intensity different between to adjacent bars that can just be detected) to gratings with a number of different orientations.

Question 14

contrast grating threshold

Answer 14

1.Measure a person’s contrast threshold

2. The contrast threshold measured by changing the intensity difference between the light and dark bars until the bars can just barely be seen contrast threshold.
3. Adapt the person to one orientation by having the person view a high-contrast adapting stimulus for a minute or two.
4. Remeasure the contrast threshold of all the test stimuli presented in step 1

• In other words, adapting vertical feature detectors should make it is necessary to increase the difference between the black and white vertical bars in order to see them.

The selective adaptation experiment is measuring how a physiological effect (adapting the feature detectors that respond to a specific orientation) causes a perceptual result (decrease in sensitivity to that orientation).

Question 15

selective rearing

Answer 15

behind selective rearing is that if an 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 16

selective adaption

Answer 16

neural plasticity or experience-dependent plasticity—the idea that the response properties of neurons can be shaped by perceptual experience

Question 17

receptive field

Answer 17

an area of the retina that when stimulated, influences the firing of that neuron

Question 18

contextual modulation

Answer 18

• Neuron’s response can be affected by what is happening outside the neurons receptive field
• Recorded neurons from a monkeys cortex
• bars are presented along with the inside of the field bar WHICH LED to large increase in firing
• the effect of stimulating the outside of the receptive field
• the large response that occurs when the 3 lines are presented together may be related to perceptual organisation; how lines of the same orientation are perceived as a group

Question 19

use it or lose it

Answer 19

• Colin Blakemore and Grahame Cooper (1970) placed kittens in striped tubes like the so that each kitten was exposed to only one orientation, either vertical or horizontal.
• The kittens were kept in the dark from birth to 2 weeks of age, at which time they were placed in the tube for 5 hours a day; the rest of the time they remained in the dark.
• after 5 months of selective rearing, they seemed blind to the orientations that they hadn’t seen in the tube.
• This cat, which was reared in a vertical environment, has many neurons that respond best to vertical or near- vertical stimuli, but none that respond to horizontal stimuli. The horizontally responding neurons were apparently lost because they hadn’t been used. The opposite result occurred for the horizontally reared cats.
• oblique effect: people perceive vertical and horizontal lines better than slanted lines.
• the response of human neurons reflects the fact that horizontals and verticals are more common than slanted lines in our environment

Question 20

charles gross IT cortex

Answer 20

• removing parts of the IT cortex in monkeys affected the monkeys’ ability to tell the difference between different objects
• neurons in the IT cortex respond to complex stimuli –> found a neuron that refused to respond to any of the standard stimuli like oriented lines or circles or squares.
• hand shadow caused a burst of firing
• After expanding the types of stimuli presented, they also found some neurons that responded best to faces.
• created neurons that responded best to very specific types of stimuli.
• FFA

Question 21

fusiform face area

Answer 21

responded strongly to faces

Question 22

spatial organisation

Answer 22

different locations in the environment and on the retina are represented by activity at specific locations in the visual cortex.

Question 23

retinotopic map

Answer 23

the electronic map of the retina on the cortex (organised spatial map)
- each place on the retina corresponds to a place on the LGN (striate cortex) (location

Question 24

cortical magnification

Answer 24

more space being allotted to locations near the fovea than to locations in the peripheral  this apportioning of a large area on the cortex to a small area is called cortical manginfication

Question 25

MRI

Answer 25

create images of structures within the brain

standard technique for detecting tumours& other brain abnormalities (doesn’t indicate brain activity)

Question 26

fMRI

Answer 26

enables researchers to determine how various types of cognition activate different areas of the brain

• The fmri apparatus determines the relative activity of various areas of the brain by detecting changes in the magnetic response of the haemoglobin

Question 27

location column

Answer 27

location column serves one location on the retina (all neurons in the column have their receptive fields at about the same place on the retina) and contains neurons that respond to all possible orientations

Question 28

adjacent columns

Answer 28

change preference in an orderly fashion
The columns alternate in a left-right pattern every .25 to .50 mm across the cortex
- adjacent orientation columns

Question 29

hypercolumn

Answer 29

A single location column
Left and right dominance columns
complete set of orientation columns (0 to 180 degrees) • This is called the “ice-cube” model.

Question 30

Ocular dominance columns

Answer 30

Neurons in the cortex respond preferentially to one eye.

Neurons with the same preference are organized into columns.

Question 31

tiling

Answer 31

Working together, these columns cover the entire visual field, an effect called tiling

Question 32

Lesioning or Ablation Experiments

Answer 32

1. First, an animal is trained to indicate perceptual capacities.
2. specific part of the brain is removed or destroyed.
3. the animal is retrained to determine which perceptual abilities remain.
4. The results reveal which portions of the brain are responsible for specific behaviours.

Question 33

object discrimination problem

Answer 33

a monkey was shown one object, a rectangular solid, and was then presented with a two-choice task which included the “target” object (the rectangular solid) and the triangular solid.
- If the monkey pushed aside the target object, it received the food reward that was hidden in a well under the object.

Question 34

Landmark discrimination problem

Answer 34

The landmark discrimination problem monkey’s task was to remove the cover of the food well that was closest to the tall cylinder.

Question 35

what pathway discovered

Answer 35

In the ablation part of the experiment, part of the temporal lobe was removed
- behavioral testing showed that the object discrimination problem was very difficult for these monkeys.
- pathway that reaches the temporal lobes is responsible for determining an object’s identity
what pathway: pathway leading from the striate cortex to the temporal lobe
ventral

Question 36

where pathway

Answer 36

• Other monkeys had their parietal lobes removed, and they had difficulty solving the landmark discrimination problem.

This result indicates that the pathway that leads to the parietal lobe is responsible for determining an object’s location

where pathway: the pathway leading from the striate cortex to the parietal lobe

Question 37

neuropsychology

Answer 37

the study of the behavioural effects of brain damage in humans.

Question 38

The Behaviour of Patient D.F.

Answer 38

Milner and Goodale

• double dissociations to study D.F (a women who suffered damage to her ventral pathway)
• She was not able to match the orientation of a card held in her hand to different orientations of a slot.
• when D.F. was asked to “mail” the card through the slot, she could do it! Even though D.F. could not turn the card to match the slot’s orientation, once she started moving the card toward the slot, she was able to rotate it to match the orientation of the slot
• D.F. performed poorly in the static orientation-matching task but did well as soon as action was involved
• one mechanism for judging orientation and another for coordinating vision and action

 can judge visual orientation, but they can’t accomplish the task that combines vision and action.
- D.F.’s ventral stream is damaged, these other people have damage to their dorsal streams = double dissociation

Question 39

double dissociations

Answer 39

other patients whose symptoms are the opposite of D.F.’s.

involve two people: In one person, damage to one area of the brain causes function A to be absent while function B is present; in the other person, damage to another area of the brain causes function B to be absent while function A is present.

Question 40

single association

Answer 40

Evidence of a deficit occurring in the absence of another deficit. For example, difficulty perceiving faces but still being able to perceive objects. or difficulty reading non-words, but being able to read words

Question 41

modules

Answer 41

Areas that are specialized to specific types of stimuli areas are called modules for processing information about these stimuli.

Question 42

parahippocampal place area (PPA)

Answer 42

activated by pictures depicting indoor and outdoor scenes

what is important for this area is information about spatial layout, because increased activation occurs both to empty rooms and to rooms that are completely furnished

Question 43

the extrastriate body area (EBA)

Answer 43

, is activated by pictures of bodies and parts of bodies (but not by faces),

Question 44

Lateral occipital complex (LOC)

Answer 44

object recognition

Question 45

Evolution and Plasticity:

Answer 45

• Evolution is partially responsible for shaping sensory responses:
• Newborn monkeys respond to direction of movement and depth of objects
• Babies prefer looking at pictures of assembled parts of faces
• Thus “hardwiring” of neurons plays a part in sensory systems

Question 46

The Expertise Hypothesis:

Answer 46

The fact that experience with the environment can shape the nervous system

our proficiency in perceiving certain things can be explained by changes in the brain caused by long exposure, practice, or training