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Flashcards in Building the brain Deck (16)
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1
Q
How many neurones are in the brain?
How many inputs does a neuron contain?
How much neurostransmitter information is transmitted by 1 input in 3-5 milliseconds?
How many connections are in the brain?
How long can a neuron be?
A

Scale factors of the brain:
> 100 billion neurons = 10% of brain cells
> 1 neuron = 30,000 inputs
> 1 input can transmit 5,000 quanta neurotransmitter (information) in 3-5 milliseconds
> 1,000 connections
> 1 neutron can be 1-3m long

<=> if you (neuron) are in a stadium, you can touch 30,000 people at the same time

2
Q

What composes the forebrain (telencephalon)?

A

Diencephalon

  • Thalamus: motivational drive, libido
  • Hypothalamus: eat, drink, sleep
  • very important, basic, critical functions
  • needs input from the brain stem (tronc cérébral)

Cerebrum (cortical lobes)

  • Occipital lobe: visual cortex (receiving and intepretation)
  • Temporal lobe: auditory cortex (speech) ; memory (episodic ‘autobiographical’ ; semantic)
  • Parietal lobe: primary sensory cortex (integration of sensory info ; problems in this area -> agnosia, apraxia)
  • Frontal lobe: prefrontal cortex (PFC) ; primary motor cortex
3
Q

What is the prefrontal cortex (PFC)?

A

> All of the frontal lobe apart from primary motor cortex

> Higher functions that make us human:

  • personality/expression
  • social awareness
  • goal-setting
  • attentive and task-switching
  • executive functioning
4
Q

What is the evolution of the nervous system?

A

Each time a new part evolved, it built on top of earlier parts
-> deep parts (under the surface of the cortex) are more ancient

  1. Spinal cord and brain stem
    - sophisticated reflexes
    - autonomous organ control
  2. Hypothalamus
    - basic functions (eat, drink, reproduce)
    - primal behaviours
  3. Limbic and hippocampal system
    - emotional processing and memory
  4. Cortical growth
    - higher cognitive processing
    - “makes us human”
5
Q

What does the hypothalamus regulate?
What are its inputs and functions?
How its critical neurotransmitter inputs?

A

> Size of an almond
Regulates a large number of primal/basic behaviours (appetite, motivation, reproduction)

Inputs:

  • Sensory: taste, smell, genitals
  • Eyes: light input as ‘zeitgeber’ (tells its day or night, hunt or hide) -> circadian pattern
  • Hippocampal memory input
  • Amygdala emotional (aversive memory) input
  • Neurotransmitters: serotonin, noradrenaline -> key for appetite and motivation ; critical for the appropriate functioning of the hypothalamus

Functions:

  • Sexual behaviour (core function): Hypothalamic Pituitary Axis (HPA = menstruation, spermatogenesis) ; male mounting, female hip elevation ; interpretation of pheromones
  • Motivational behaviour: basic/primal (food, water, reproduction) = appetitive / consummatory motivation

Critical neurotransmitters:
- without serotonin and noradrenaline - biological side effects (found in depression)

6
Q

What is the role of the prefrontal cortex (PFC) in regards to the hypothalamus?

A

The ancient parts of our brain (hypothalamus) are very strong drivers of human behaviour
BUT our prefrontal cortex (PFC) can control and nuance them

7
Q

What are the limbic and hippocampal systems?

What do they regulate?

A

> Phylogenetically ancient systems

  • with us for 100+ million years
  • > sits in the ‘deep’ subcortical part of the brain

Limbic system
- ‘pure emotions’ (anger, fear, happiness)
= primal drivers

Hippocampal system
- controls function of memory
- Hippocampi (plural of hippocampus): memory formation; 3 neuronal layer of cells (usually 6) -> ancient part of brain ; connects with various regions
- Amygdalae: aversive (fearful) memory -> assists survival
(unwanted thoughts keep occurring ; thought is linked to stimulus)
(in PTSD: pathological dysfunction of the amygdala-hippocampi pathway)

8
Q

Why was the hypothalamus developed before the limbic and hippocampal systems?

A

At first, it was more important to develop a survival system for seeking food, water, and reproducing -> hypothalamus
Then, we developed an emotional system -> limbic and hippocampal systems (on top of the hypothalamus)

9
Q

What is the ‘Circuit of Papez’?

A

In the hippocampi

  • long-term potentiation (LTP)
  • which is necessary for the encoding, storage, and retrieval of memory
10
Q

What are Hominin and Hominids?

A

Hominin + Hominids = Humans

> Hominin: any species that came before us
Hominids: great apes

11
Q

What is sexual dimorphism?

How does it relate to the famous 4-million year old picture of anthropology saw in the lecture?

A

Sexual dimorphism:
- distinct difference in size or appearance between the sexes of an animal

Famous picture: 2 close sets of footprints

  • female and male
  • female’s footprints are deeper
  • > hypothesis: she was carrying a child
  • they were Australopithecus
12
Q

What is Australopithecus?
What was it’s lifespan, cranial capacity?
What is their evolution significance?
What are the evolutionary bipedalism advantages and disadvantages?

A

> “southern stone man”
Grandfather of Homo Sapiens
Lifespan: 4.2 - 1.2 million years ago
Cranial capacity: 3-600 cm3 (= chimpanzee)

> Evolution significance:
- they show we walked before we got smarter

> Evolutionary (bipedalism) advantages:

  • walked longer distances
  • moved from trees to plains
  • new posture -> cooler -> more hours active
  • hands free to make and carry tools, master fire
  • able to get more food (than needed to survive)
  • > enough energy available for brain growth and development

> Evolutionary (bipedalism) disadvantages:
- locked hips -> difficult childbirth

13
Q

What is the evolution of the genus Homo, from Australopithecus to Sapiens?

A

Australopithecus (4.2-1.2 mya)

  • > Homo habilis (2.2-1.4 mya)
  • > Homo erectus (1.8-1.3 mya)
  • > Homo heidelbergensis (600,000-200,000 years ago)
  • > Homo sapiens, neanderthal, denisova
14
Q

What are the 3 species derived from the same ancestor that were living side by side, 200,000 years ago?
What is that common ancestor?

A

Homo heidelbergensis (common ancestor)

  • > 3 species:
  • Neanderthal range (Europe)
  • Denisova hominin (Asia)
  • Homo sapiens (Africa): “wise”/”knowing” man
15
Q

What are the differences between Homo neanderthalensis and Homo sapiens?

A

Homo neanderthalensis

  • complex culture
  • tool making
  • language
  • Physical attributes: stocky (stronger than sapiens), large cranial volume (larger than sapiens)
  • Hunting style: ambush larger prey
  • Cognitive makeup: large occipital cortex (very good vision, including at night)

Homo sapiens

  • Physical attributes: nuchal ligament (connects skull to spine), strong Achilles tendon
  • > run over longer distances than neanderthal
  • Hunting style: persistence hunters (chase down/follow prey over long distances)
  • Cognitive makeup: smaller occipital cortex ; larger orbital frontal cortex (key to social behaviour and mentalisation) = ultimate difference

=> Sapiens: our physical attributes made us better hunters - outcompete neanderthal

16
Q

What is the genetic history from 200,000 years ago to modern day?

A

200,000 - 70,000 years ago
> 7bn people on the planet, all incredibly connected
> Event: Supervolcano (approx. 70,000 years ago)
- largest known explosion on Earth for the past 25 million years
- Lake Toba (current Indonesia)
- Mitochondrial DNA (mDNA) findings
-> population dropped to: population of 10,000 or less remained
-> all humans follow this lineage

50,000 - 12,000 years ago
> Behavioural explosion
- buried our dead
- huge increase in artwork and jewellery
> We spread from Africa, through the Levant, across the world
> Wiped out Neanderthalensis
12,000 years ago - modern day
> Neolithic revolution
- animal domestication and farming
- rise of great cities: Ur, Babylon, Jericho
- first empires: Persian, Assyrian, Egyptian
> Bronze Age
> Iron Age
> Industrial Revolution
> Scientific Revolution
> Computer and information Revolution