Lecture 2 - Cerebral Cortex

Question 1

Rank 6 species discussed in class from highest # of neurons to lowest # of neurons

Answer 1

1. Humans - 86-120 billion (whales and elephants might have more - 250?)
2. Octopus
3. Dog
4. Cat
5. Fruit Fly
6. Lobster - 100,000

Question 2

How thick is the cerebral cortex on average?

Answer 2

2-3mm

Question 3

The cerebral cortex has wrinkles. How are those wrinkles classified?

Answer 3

Gyri/lobules - the hills
Sulci/fissures - the valleys

Question 4

You can identify borders of different neural functions by following the patterns of the sulci (T/F)

Answer 4

F!

Question 5

The bundle of white matter connecting the two hemispheres of the brain is known as the:

Answer 5

Corpus Callosum!

Question 6

What are the 3 main fissures of the cerebral cortex?

Answer 6

Longitudinal
Central (Rolandic)
Lateral (Sylvian)

Question 7

What are the 4 lobes of the brain?

Answer 7

Frontal, parietal, temporal, occipital

Question 8

What are the two ‘hidden’ lobes of the cerebral cortex?

Answer 8

Limbic & insula

Question 9

What structures comprise the limbic lobe? (5)

Answer 9

Cingulate gyrus
Hippocampus
Parahippocampal gyrus
Uncus
Subcallosal gyrus

Question 10

What are the functions of the limbic & insula lobes?

Answer 10

Limbic - emotional drive & survival instinct
Insula - related to sensorimotor functions (apraxia of speech) and limbic functions (e.g. self-awareness, social emotion, etc.)

Question 11

What structures are highlighted in the medial view of the brain? (7)

Answer 11

Cingulate gyrus
Corpus callosum
- Anterior commissure
- Genu, Body, Splenium
- Fornix
Lateral ventricle
Thalamus
Hypothalamus
Precuneus & Cuneus
Lingual gyrus

Question 12

What structures are highlighted in the ventral view of the brain? (8)

Answer 12

Inferior temporal gyrus
Pre-occipital notch
Olfactory tracts and bulbs (smell)
Optic nerve and chiasm (vision)
Hypophysis (pituitary gland – homeostasis hormones)
Mammillary bodies (memory)
Parahippocampal gyrus (memory)
Uncus (smell, memory, emotion)

Question 13

What structures are highlighted in the lateral view of the brain? (3)

Answer 13

Frontal lobe
- Precentral gyrus
- Primary motor cortex (4)
- Somatotopically organized
Premotor cortex (6)
- Supplementary motor area
- Superior frontal gyrus
- Middle frontal gyrus
Inferior frontal gyrus
- Contains Broca’s area (BA 44/45)

Question 14

Who is Brodmann? What did he do?

Answer 14

German anatomist in the 19th century.
Created a cytoarchitectonic map – based on the type of cells and their density in various regions of the brain. Map was later enhanced by Canadian neurosurgeon Walter Penfield.
- “zapped” the map to determine function
- Epilepsy surgery
- Patients were awake!

Question 15

Brodmann’s areas 41 and 42 make up what?

Answer 15

Auditory cortex

Question 16

Brodmann’s areas 44 and 45 make up what? What is 44 specifically?

Answer 16

Motor speech - Broca’s is 44 specifically

Question 17

Brodmann’s areas 1, 2, & 3 make up what?

Answer 17

Primary somatosensory cortex

Question 18

Brodmann’s area 4 makes up what? What is its function?

Answer 18

Primary motor area (execution)

Question 19

Brodmann’s area 6 makes up what? What is its function?

Answer 19

Premotor area (planning)

Question 20

What are the primary and secondary/association Motor areas (Brodmann’s)

Answer 20

Primary- 4
S/A- 6, 9/10, 11, 44

Question 21

What are the primary and secondary/association Sensory areas (Brodmann’s)

Answer 21

Primary - 1,2,3
S/A - 7, 39, 40

Question 22

What are the primary and secondary/association Auditory areas (Brodmann’s)

Answer 22

Primary - 42
S/A- 22

Question 23

What are the primary and secondary/association Visual areas (Brodmann’s)

Answer 23

Primary - 17
S/A - 18, 19

Question 24

3 structures within the inferior frontal gyrus are the pars _____, ______, and _____ (“TOO”)

Answer 24

triangularis, orbitalis, opercularis

Question 25

Describe the primary motor cortex

Answer 25

It’s a map of muscles in the body, a ‘homunculus” for contralateral side

Question 26

The primary motor cortex is a pure homunculus without redundant representation of muscles (T/F)

Answer 26

F!
Not pure & it is redundant

Question 27

There is not a 1:1 relationship within the primary motor cortex (T/F)

Answer 27

T. One mm^2 of neurons does not equal one muscle

Question 28

Representation of the primary motor cortex is based on size (T/F)

Answer 28

F. Based on refinement - leg has small representation but are physically large body parts

Question 29

T/F: The primary motor cortex is sensitive to environmental change

Answer 29

T. It is plastic!

Question 30

The premotor cortex is referred to as what? What is it responsible for

Answer 30

A second map! Responsible for sequence of movements

Question 31

How is the premotor cortex moderated?

Answer 31

by input from feedback centers (cerebellum, basal ganglia and thalamus)

Question 32

If the primary motor area are construction workers, the premotor cortex is what?

Answer 32

The blueprint!

Question 33

What two regions of the prefrontal cortex were highlighted in class?

Answer 33

Dorsal prefrontal region & orbital prefrontal region

Question 34

What are the responsibilities of the dorsal prefrontal region of the prefrontal cortex?

Answer 34

Short-term memory, executive function (e.g. decision making), critical for learning!
Planning & problem-solving (e.g. Tower of Hanoi)

Question 35

What are the responsibilities of the orbital prefrontal region of the prefrontal cortex?

Answer 35

Emotional regulation, adaptive behaviour, social cognition, inhibition/self control
- Affected in Fetal Alcohol Syndrome