Workshop 1: Brain evolution & Animal models

Question 1

Triune brain theory

Answer 1

• we have 3 brains:
• reptilian
• paleomammalian
• neomammalian▪ Developed in the 1960s by Paul D. Maclean
  ▪ Three distinct brains emerged through evolution which co-inhabit the human skull▪ These three brains do not operate independently
  ▪ Numerous interconnections through which the regions influence each other (very coordinated)
  - The brain did not evolve in successive stagesTherefore… the theory is not widely accepted today

Question 2

Triune brain theory: Reptillian brain

Answer 2

▪Oldest part
* 300 million years
▪Main structures found in a reptiles brain
* Brainstem
* Cerebellum
Functions:
▪“Regulating & Surviving”
▪Vital functions (digestion, food searching, defence, reproducing)
▪Basic behaviours (survival)
* Defending territory
* Mating
▪Instinctive and automatic

Question 3

Triune brain theoy: Limbic brain/ Paleomammalian brain

Answer 3

▪ aka “paleomammalian” brain
▪ Emerged in the first mammals Limbic system
▪ i.e., the feeling centre Main structures:
▪ Hippocampus
▪ Amygdala
▪ Hypothalamus
Functions:
▪ Helps keep internal state of the body constant: (homeostasis)
* Hunger with satiation
* Thirst with fluid retention
* Sweating when hot
* Shivering when cold
* Etc…
▪ Controls emotions
▪ Seat of value judgements
▪ Fear, anger, love, attachment and bonding

Question 4

Triune brain theory: Neocortex/ neomammalian brain

Answer 4

▪ Emerged in primates but is most important in humans
Functions:
▪ The thinking brain (Rationalising)
▪ Moderator – reining in instinct and emotional responses
▪ Allows for cooperation
▪ Responsible for the development of language, imagination and consciousness
▪ Flexible with almost infinite learning abilities (millions of neurones)
Metacognition

Question 5

Our brain has evolved

Answer 5

Brain size increased (brain-body ratio)
(encephalisation quotient - sophisticated way of displaying this)

▪Proportion of the different areas changed 

▪Folding of cerebral cortex increased

Question 6

Bird intelligence

Answer 6

Mclane talked about how it was unique to humans…?

- Similar than originally thought to human brains
- Capable of complex behaviours Study on crows - Inserted electrodes into brain to observe activity before making a decision

Question 7

Evolution of humans

Answer 7

2. Homo Habilis <——- Homo Naledi

Question 8

Homo Naledi

Answer 8

Same genus, different species

Primates

Did display social behaviours (art, burying the dead…)

Found deep in caves - even in tight spaces

- Around the time of Australopithecus robustus & Homo habilis
- Credited to similarly to large prefrontal cortex
	○ Originally thought we were the first with large context More out there to discover

Question 9

Einstein’s brain

Answer 9

• Found to be smaller than the average brain
• What changed were the interconnections & white matter (more)

Question 10

Reading task: Animal research, for

Answer 10

• Animal experiments have also contributed significantly to the development of vaccines, antibiotics, and our fundamental understanding of human disease processes. Albert Sabin used monkeys in the 1930s to develop the polio vaccine
  • Insulin was discovered in the 1920s using canines, and the foundation of diabetes research relied on genetically modified mouse and rat models
  • majority of antibiotics are tested on animals prior to use in humans

Mice have similar brain structure to humans = useful

Question 10

Animal research: against

Answer 10

▪ Unpredictable translation of animal models to humans leading to concerns over clinical validity, application, and ethics (extrapolation) Can have different evolution of deiseases, physiological structures, recovery from disease…
▪ Three areas of concern
1. Study design and data analysis (rigorous? Scientific?)
2. Heterogeneity of animals and humans
3. Translation of preclinical animal trials to human clinical
- In animal studies, however, this placebo effect is not pertinent. Rather, animal subjects are routinely exposed to potentially harmful and painful procedures, with no benefit
- Singer, speciesism
Alfred Wallace Russel - idea of reducing, reusing, recycling

Question 11

Animal Study design issues:

Answer 11

▪ Inconsistent designs
▪ Lack of randomisation
▪ Lack of blind studies
▪ Inadequate of absent use of inferential statistics (need enough pps)
▪ Many trials concurrent, or even after, human studies (is it needed?)

Question 12

The three R’s

Answer 12

(Russel and Burch, 1959)
* Replacement, Reduction, Refinement (e.g. in vitro studies using animal cells, not whole animal)