Association Cortices

Question 1

What is meant by association cortices?

Answer 1

Include most of the cerebral surface of the human brain and are largely responsible for the complex processing that goes on between the arrival of input in the primary sensory cortices and the generation of behaviour

Question 2

How many layers are in the human neocortex?

Answer 2

6 layers
1. Molecular
2. External granular
3. External pyramidal
4. Internal granular
5. Internal pyramidal
6. Multiform

Question 3

Why is there different layers in the cortex?

Answer 3

Allows for information to be processed in a feed-forward manner by having different inputs in each layer and outputs in other layers

Question 4

What are Brodmann’s areas?

Answer 4

A region of the cerebral cortex defined by its cytoarchitecture or histological structure and organisation of cells

Question 5

How is the brain divided up in terms of Brodmann’s areas?

Answer 5

Cortex can be divided into 52 areas which are numbered sequentially

These areas are distinguished by microscopic anatomy through the shapes and types of cells and their connections

Question 6

What are the major connections of the neocortex?

Answer 6

Hippocampal formation
Amygdala
Thalamus
Brainstem modulatory systems

Question 7

What are the targets of cortical output?

Answer 7

Hippocampal formation
Amygdala
Thalamus
Caudate and putamen (striatum)
Brainstem
Spinal cord

Question 8

What disorder arises from lesions to the parietal association cortex?

Answer 8

Contralateral neglect syndrome
= The inability to attend to objects in a portion of space, despite the fact that visual acuity, somatic sensation and motor ability remains intact

Typically associated with damage to the right parietal cortex as the right parietal lobe is usually dominant for attention

Question 9

What does contralateral neglect syndrome tell us about the parietal association cortex?

Answer 9

Links the parietal lobe to attention and perceptual awareness

Question 10

What does electrophysiological data from monkeys show during attention, identification and planning paradigms?

Answer 10

Attention-sensitive neurons can be identified by recording electrophysiological changes in neuronal activity associated with simultaneous changes in attentive behaviour of the animal

Specific regions of the parietal cortex of the rhesus monkey are activated when the animal attends to a target, but not when the same stimulus is ignored

Question 11

What has brain lesions taught us about the temporal association cortex?

Answer 11

The function of the temporal lobe association cortex must be recognition and identification of stimuli that are attended to, particularly complex stimuli

Question 12

What disorders are associated with lesions to the temporal lobe association cortex?

Answer 12

Agnosias
= Patients are able to acknowledge the presence of a stimulus but are unable to say what it is

Question 13

What is a common structure in the temporal association cortex?

Answer 13

The fusiform face area = important for facial recognition

Question 14

What is the inability to recognise or identify faces?

Answer 14

Prosopagnosia

Question 15

What do brain lesions tell us about the frontal lobe association cortex?

Answer 15

Phineas Gage = personality
Brain lesions in the frontal lobe affect performance in the Wisconsin card sorting task - work out the rule of organising cards
Also affects the Tower of Hanoi
Frontal lobe lesions also cause problems with impaired restraint, disordered thought, perseveration and the inability to plan appropriate action

Question 16

What is the delay response task?

Answer 16

Monkey watches experimenter place a piece of food in one of two wells; both wells are covered
A screen is lowered for a second to several minutes
When the screen is raised the monkey gets one chance to choose the well with the food in it

Tests the monkeys working memory = must work out that it wants the food, remember where it was place, recall this information to retrieve the food and then keep all that information available during the delay so it can be used to get the delay

Question 17

What abolishes a monkey’s ability to complete the response delay task?

Answer 17

If the prefrontal cortex is destroyed bilaterally

Question 18

What happens if these prefrontal neurons are damaged?

Answer 18

Monkeys lose the ability to execute sequences of movement from memory

Question 19

What do the findings from Phineas Gage and prefrontal neurons tell us about the function of the frontal lobe?

Answer 19

Frontal lobe contributes to the cognitive functions that use remembered information to plan and guide appropriate sequences of behaviour

Question 20

What are Jennifer Aniston neurons?

Answer 20

A hypothetical neuron that represents a complex but specific concept or object

It activates when a person sees, hears or otherwise sensibly discriminates a specific entity such as their grandmother

Question 21

What techniques have been used to study association cortices?

Answer 21

Diffusion tensor imaging - can identify large bundles of axons connecting brain areas in humans

Brain lesion patients - inferences about the function of human association areas due to cognitive deficits