Lecture 3 - The Central Nervous System

Question 1

Introduce the Nervous system

***does the spine protect the spinal cord, or is it the spinal cord that protects the spine?

Answer 1

•The Nervous system
- sends out and receives messages throughout these pathways

•The main pathway = spinal cord

• protected by the spine
• the motorway of transmission in the nervous system

•Neurons send excitation down and across the synpatic gap, via chemicals
- trillions of connections

•There are lots of systems in the body, e.g. but the

Question 2

What are the 2 main systems that neurons are organised into?

Answer 2

Neurons are organised into networks that transmit physical stimulation in and out

2 Main Systems: with different functions:

1. Central System
2. Peripheral System

They are joined though

Question 3

What does the central nervous system do?

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Answer 3

Central NS controls: “Higher functions:

• from sensation to thinking
• Mostly our brain
• seat of higher sensations/ abilities/ capacities
• Thinking, perceiving, recognising, language etc

Peripheral NS regulates: Housekeeping functions

• just keeps you alive, not as prestigious
• keeps you at optimal level of functioning
• Broken down into 2 parts: 1. Sensory (somatic), 2. Autonomic

Question 4

Outline the 2 divisions of the Peripheral Nervous system and their roles
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Answer 4

1. Sensory (Somatic) NS
   - paired with motor system (Coordination, perception, sense etc)
   - linked to sensory receptors
   - It connects the CNS to sense receptors, muscles etc
2. Autonomic
   - It connects the CNS to the vital organs
   - takes care of itself
   - has 2 branches itself

Question 5

Outline the 2 divisions of the Autonomic Nervous system and their roles

Answer 5

Either excite or inhibit

1. Parasympathetic - relaxes
   - mediates responses associated with a relaxed state
   - Heart slows
   - lungs slow down breathing
   - blood vessels constrict again
   - digestion: re-initiates
2. Sympathetic - pushes
   - mediates responses associated with arousal
   - heart speeds up
   - breathings speeds up
   - blood vessels dilate - blood flow around system
   - digestion shut off, need blood and energy for important stuff

Question 6

How neurons in elephans and humans differ?

Answer 6

• Elephants have many more neurons than humans
• BUT humans have more dendrites, axons and terminal buttons, so ultimately we have many many more connections
• This enables us to do the higher order functions, that seperate us from other mammals

Question 7

Evolution related stuff includes

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Answer 7

1. First family - Australopithecus
2. Our family began - Homo family
3. What are neanderthals and when were they
4. What happened to neanderthals?

Question 8

Outline the first family - Australopithecus

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Answer 8

4 MIllion years ago

• Can began to trace a family of organisms: Australopithecus
  1. Shared genetic material
  2. Shared geographic habits/ behavioural habits
  3. Evidence from skeletal remains - wear and tear on leg bones indicate they walked on two feet
  4. Also found remains near evidence of fire! An initial distinction between them and other animals
  5. Also used tools - other animals kind of did, but these were stone tools - that required a bit of work
• again sets them aside from other animals

Question 9

Outline when our family began - The Homo family

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Answer 9

2. 5 Million Years Ago - the Homo family began
3. We began to use our hands in a skilled way - Homo Habilis = hand
4. Homoerectus = doing things upright

250,000 Years ago

• Homo Sapiens came about
• Sapien = using knowledge
• Cohabited with Neanderthals with around 250,000 years, they were another species

Question 10

What are neanderthals?

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Answer 10

Homo Neanderthalensis - called this because first remains were found near Neander Valley
Another species that cohabited with homosapiens for around 250,000 years
- Nowadays its a bit of an insult, but were they the same?

1. Some differences in brain & skull size
   - perhaps they were less intelligent
2. Evidence suggests they could do the same stuff we could
   - e.g. kill from distance. They found a spear near remains. This is quite an advanced skill, as it requires perceptual and coordination skills
   - other primates cant really do this, they can just sort of lob things, not track and target
3. More and more evidence to suggest they werent that
   unintelligent
4. Present in our genes, and lived in similar places

Question 11

When were neanderthals/ Homo Sapiens

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Answer 11

• Homo Neanderthalensis: 250,000-300,000 years ago

* Homo Sapien: 200,000 years ago- now

Question 12

What are the 3 theories for what happened to Neanderthals?

Answer 12

1. Environmental Change
   - They might have been too dependent on one area, e.g. the savannah, then when ice came along, they were unable to adapt and forage - perhaps due to their limited intelligence/ limited perceptual ability
   - BUT WE COULD SO WE SURVIVED
2. Victims of inadvertent genocide - not nice idea
   - Might have been victims to an inadvertent homosapien genocide - perhaps because we introduced them to diseases they were not immune to
3. Victims of purposeful genocide - darkest idea
   - In competition for resources, like food, water and land, homosapiens purposefully killed them all, as they saw them as rivals/ threat
   - We could beat them as we had better weopanry skills, organisation, discipline, communication etc

Question 13

Outline Neuroanatomy - how much has been present for a long time

Answer 13

So: our systems have been running for 250,000 years

• but the brain is pretty much the same
• only things that have changed have been due to culture, like behavioural tendencies or feelings
• some people argue not much has changed and this accounts for a lot of modern behaviours

3 Basic structures that have been present for a long time:

1. Forebrain (Youngest structure)
2. Mid brain (Second Oldest)
3. Hindbrain (Oldest)

Question 14

Outline the forebrain

Answer 14

Has some very powerful structures in it:

1. Cortex
   - this is where everything that makes us human takes place - imagining, reasoning, problem solving, language, thinking, memory
   - 5 sense take place here
   - These abilities are what 250,000 years of evolution has given us
   - lots of neurons here, primates have less here
   - Yes primates can solve problems but our abilities are much more advanced - we can solve problems when we are 3!
2. Limbic System
   a) Hippocampus
   b) Hypothalamus
   c) Corpus Callosum - stradels both hemispheres
   •This area is associated with feeding, drinking, sex etc
   - Debate around how much of this you can actually control - are they just evolutionary strategies that are out of our control

Question 15

Outline the midbrain

Answer 15

Houses the reticular formation

- associated with sleeping/ waking

Question 16

Outline the Hindbrain

Answer 16

•Oldest part of the brain evolutionarily - does all the housekeeping stuff

• the autonomic nervous system (para/sympathetic) goes through
• it’s housed at the top of the brain stem, latching onto the spinal column

Includes:

1. Cerebellum - Muscular & Skeletal co-ordination
   - walking, balance, navigating the world, movement, being in control of your body
2. Medulla - Heart, circulation, breathing

Question 17

What re the 4 cortical lobes

Answer 17

These are implicated when there is damage from the outside world:
1. Occipital, 2. Frontal, 3. Temporal, 4. Parietal

Question 18

Outline the cortex

***meninges

Answer 18

1. 3mm Surface of the brain - not just in one place, all over the brain
2. Has Folds & Fissures to increase surface area
   - more space available for neurons
3. The most dense neuronal area - 10 billion neurons in this tiny strip around the brain
4. Meninges - soft tissue in between the surface of the brain and the skull - inflamed in Meningitis

Question 19

Outline cortical damage

Answer 19

So it’s an evolutionary trade-off, yes the cortex is the area with the most neurons, and the highest availability of function

• but in being so, it is also the most vulnerable to the outside world
• if there are external blows from the outside, the cortex gets hit first

•Internal stuff is relatively protected, and that is because it controls your vital organs/ bodily functions
- you can survive without language skills or whatever, but cannot survive without bodily functions going

•Easier to spot damage/ lesion if its on the outside of the brain - easier to correlate behaviour/ symptoms of the person before they died if the damage is visible from the outside

•E.g. Broca’s Aphasia - can’t produce talk
- Broca opened the skull and saw damage in the cortical area now known as Broca’s area

Question 20

Outline phrenology

Answer 20

Phrenologists argue different areas of the brain are associated with different abilities

• e.g. trustworthiness, Caution
• therefore, someone who is good at language would have a larger language area
• much like how a rower would have bigger rowing muscles
• developed maps/ models

This movement didnt really take off

• but some people use it to look at skulls of previous species and infer what they might have been good at
• or they were less trustworthy or instance