Lecture 1: Evolutionary History of the Brain

Question 1

How does the brain use sensory input to guide movement?

Answer 1

Input from sense organs -> brain -> output to muscles

Question 1

What are the two main functions of the brain?

Answer 1

1. Use sensory input to guide movement
2. Use sensory input to regulare internal organs

Question 2

How does the brain use sensory input to regulate internal organs?

Answer 2

Input from sense organs -> brain -> output to internal organs

Question 3

What is the cortex?

Answer 3

Covers the surface of the brain

Question 4

What are gyrus?

Answer 4

Bumps/ peaks in the cortex

Question 5

What are sulcus?

Answer 5

Dips in the cortex

Question 6

What are the names of the four lobes?

Answer 6

1. Frontal lobe
2. Parietal lobe
3. Occipital lobe
4. Temporal lobe

Question 7

What are the names of the two gyrus?

Answer 7

1. Precentral gyrus
2. Postcentral gyrus

Question 8

What is the name of the sulcus?

Answer 8

Central sulcus

Question 9

What are the three parts the brain can be divided into?

Answer 9

1. Forebrain
2. Midbrain
3. Hindbrain

Question 10

What is the function of the forebrain?

Answer 10

Uses current sensory input and past experience to make (and communicate) decisions

Question 11

What is the function of the midbrain?

Answer 11

Uses current sensory input to direct movement

Question 12

What is the function of the hindbrain?

Answer 12

Maintains the current state; control mouth

Question 13

What are the two systems in which the brain uses to send messages to the body?

Answer 13

1. Nervous system
2. Vascular system

Question 14

What is the nervous system?

Answer 14

• Uses electrical signals to send messages rapidly
  however communication is costly
• The network structure determines which cells receive the messages

Question 15

What is the vascular system?

Answer 15

• Uses chemical signals (hormones) so send messages slowly but cheap
• Membrane receptors determine which cells receive the message

Question 16

Where did the brain come from?

Answer 16

• Sensory and communication systems in humans are similar to those in other animals
• Structure of the human brain is similar to that of other brains
• Theory of evolution helps us understand similarities (and differences)

Question 17

When was the Earth Birth: Prokaryotic cells (no nucleus)?

Answer 17

3.5 to 2 billion years ago

Question 18

What are prokaryotic cells?

Answer 18

• membrane regulates contents, produces energy and has sensors
• cytoplasm contains molecules needed for cell to work
• flagella regulate movement
• DNA regulates protein production and allows inheritance

Question 19

When was the Oceons Rus: Eukaryotic cells (with nucleus)?

Answer 19

2 billion years ago

Question 20

What are eukaryotic cells?

Answer 20

• DNA packaged inside central nucleus
• mitochondria produce energy
• cell membrane performsphagocytosis and secretion
• microtubule network **allows complex structure
• cilia and microvilli provide specialised sensing areas

Question 21

What was Metazoa - first animals?

Answer 21

635 million years ago

Question 22

What is metazoa?

Answer 22

Cells stick together after division

→ multicellularity

• differentiated tissue (specialisation)
• digestive chamber
• intercellular signalling
• sensory cells, e.g. photoreceptors

Question 23

What was bilateria?

Answer 23

555 million years ago

Question 24

What is bilateria?

Answer 24

- complete digestive tract with separate **mouth** and **anus** - front end had concentration of **visual**, **olfactory** and **taste** sensors - **muscle**

Question 25

When was Cambrian Explosion: Chordates?

Answer 25

535 million years ago

Question 26

What is Cambrian Explosion: Chordates?

Answer 26

- **notochord** and **tail** for movement - **neural tube** for communication along body

Question 27

When were vertebrates?

Answer 27

525 million years ago

Question 28

What are vertebrates?

Answer 28

- bone **cranium** and **vertebrae** - first group with **tri-partite brain**

Question 29

When were jawed fish?

Answer 29

430 million years ago

Question 30

What are jawed fish?

Answer 30

- **teeth** → more energy - **eye muscles** for movement - three **semi-circular canals** (input for stabilisation) - **cerebellum**—to control stabilisation and gaze

Question 31

When were mammals?

Answer 31

225 million years ago

Question 32

What are mammals?

Answer 32

- **differentiated teeth** → more efficient digestion (but need fine motor control) - sensory innovations: **vibrissae** (whiskers), improved **hearing** - extended **parental care** → more **learning**

Question 33

When were primates?

Answer 33

60 million years ago

Question 34

What are primates?

Answer 34

- **opposable thumbs** *for grasping* - **binocular vision** *for focusing* - **trichromatic vision** *for colour*

Question 35

When was Homo?

Answer 35

2 million years ago

Question 36

What is Homo?

Answer 36

**Rapid expansion of brain size** in *Homo erectus*, but unclear why - **“expensive tissue”** hypothesis*better food → smaller gut → bigger brain?* - **“social brain”** hypothesis*complex social relationships → bigger brain?* - **“mating mind”** hypothesis*bigger brain → more attractive?*

Question 37

Why is there great variation in the sizes of different brain regions?

Answer 37

- Brain tissue has high **running costs**: 2% of body weight but 20% of energy - Natural selection will favour enlargement of brain region only if it enhances **survival or reproduction** - Thus brain evolution depends on an animal’s **anatomy** and **ecology**

Question 38

What does the size of different brain regions tell us?

Answer 38

The abilities of animals e.g. teleost fishes vs mammals - what should each be good at?

Question 39

What is the size of cortical area related to?

Answer 39

The importance of information it processes

Question 40

What is the importance of insight from other species?

Answer 40

Shared ancestry means that studying other animals can help us understand how our brains work