The Cortex and Localisation of function

Question 1

What is grey matter?

Answer 1

Thin (6-8mm) folded sheet of grey matter

Question 2

What are the grooves in the brain?

Answer 2

Sulci (sulcus)

Question 3

What are the ridges of the brain?

Answer 3

Gyri (gyrus)

Question 4

What makes up the white matter?

Answer 4

Corpus callosum

Internal capsule

Question 5

What is the corpus callosum?

Answer 5

Structure that links cortex of two cerebral hemispheres

Question 6

What is the internal capsule?

Answer 6

Structure that links the cortex with the brain

Question 7

Why does folding in the brain occur?

Answer 7

Accommodate massive increases in area of cortex

Question 8

How much does the cortex represent the human brain?

Answer 8

80%

Question 9

How much does the cortex represent the rat brain?

Answer 9

30%

Question 10

What is the Paleocortex/Archicortex?

Answer 10

Phylogenetically oldest part of cortex

Olfaction, emotions and memory

Question 11

What is the Neocortex (new cortex)?

Answer 11

Additional sensory areas (e.g. vision)

More sophisticated motor areas

Question 12

What do primary areas of the cortex receive?

Answer 12

Input (sensory) or give rise to a direct output (motor)

Question 13

What is the association cortex?

Answer 13

Most recent, most expanded cortex

Responsible for most complex cognitive functions e.g. speech and language

Question 14

How much does the association cortex take up in different mammalian brains?

Answer 14

5% cat brain
20% chimp brain
30% human brain

Question 15

What was Penfield study?

Answer 15

Effects of electrical stimulation of the cortex in conscious patients being prepared for brain surgery
Located a region where stimulation produced muscle twitches

Question 16

What did Penfield discover?

Answer 16

Mapping between areas of motor cortex and muscles of the body
Somatotopic map

Question 17

In what way is the motor map distorted?

Answer 17

Face and hands (fine control) have largest representation- motor homunculus

Question 18

What is the primary somatosensory cortex?

Answer 18

An are where stimulation produced sensations of numbness or tingling
Somatotopic map within stip of sensory cortex

Question 19

What is the somatotopic map in the sensory cortex like?

Answer 19

Has a greater representation of body parts (tongue, face, hands) with a high degree of sensitivity and spatial discrimination represented by sensory homunculus

Question 20

What is decussation?

Answer 20

Crossing of pathways from one side to another

Pathways providing connections between primary sensory and motor areas and the periphery are crossed

Question 21

What is Broca’s area aphasia?

Answer 21

Inability to speak while retaining comprehension of verbal and written instructions

Question 22

Where is Broca’s area?

Answer 22

Specfific region of the brain close to the motor cortex

Question 23

What is Broca’s areas function?

Answer 23

Thought to produce instructions for co-ordinated movements (of lips, tongue, mouth and larynx) for producing speech

Question 24

When is the corpus callosum cut?

Answer 24

A commisurectomy is used as a treatment for intractable epilepsy

Question 25

What are the hemispheric asymmetries for most CNS structures?

Answer 25

Bilateral and symmetrical

Question 26

What do some cortical functions show?

Answer 26

Hemispheric asymmetry

Two hemispheres perform different functions

Question 27

If an individual is right handed what does that mean?

Answer 27

Superior motor co-ordination of right hand

Question 28

What did Sperry identify in the 1960s?

Answer 28

Most patients could name objects identified by feel if placed in right hand but not if held in the left

Question 29

Where is speech predominantly functioning?

Answer 29

On the left hemisphere in 93% of the population

Question 30

What is the Wada Procedure?

Answer 30

Injection of short-acting anaesthetic into left internal carotid artery
Selectivity anaesthetises left cerebral hemisphere
Produces paralysis and loss of sensation on right side of body
Patients remain conscious
Most (93%) lose the ability to speak