Chapter 1 - Introduction Flashcards
brain
an organ consisting of living nervous tissue
- half of nerve cells are neurons (process information)
- half of nerve cells are glial cells (support neuron activity)
spinal cord
where the interconnections between the brain and the body are made
CNS
consists of the brain and the spinal cord
PNS
consists of all the nerves outside of the brain and spinal cord
cerebrum
the largest and uppermost part of the brain and is divided into 2 (almost) symmetrical halves called hemispheres
- linked to conscious behavior
cerebellum
smaller and important for movement
brainstem
responsible for our unconscious behavior
mentalism
Aristotle, from the Greek myth of Psyche, assumed that all human intelligence comes from the psyche (= spirit) and when it leaves, it will end in death
- did not value the brain and assumed that the psyche was responsible for consciousness, perception, emotion, imagination, etc.
- idea of a non-materialistic psyche solely responsible for behavior is called mentalism
dualism
the idea that behavior is controlled by 2 separate entities (mind and body); most popular proponent was Descartes
- mind was found in the brain, and connected to the body through the pineal gland
- explained the mechanical effect of the mind on the body by stating that fluid passes through chambers to control certain parts of the body
materialism
the idea that rational behavior can be fully explained by the functioning of the brain and the nervous system, without the presence of an intangible mind
- became prominent when supported by Darwin’s theory of evolution (natural selection)
- still accepted in the scientific community to this day
evolution of the nervous system in animals
- formation of neurons and muscles
- nerve net
- bilateral symmetry
- segmentation
- ganglia
- spinal cord
- brain
formation of neurons and muscles
brain cells and muscles are the first to evolve
- allows animals to move
nerve net
a net of neurons, without brain or spinal cord, with only neurons for receiving sensory information in contact with neurons for muscle movements
bilateral symmetry
the nervous system on one side of the animal is the mirror image of the other side
segmentation
the nervous system contains similar repeating segments
- in humans, seen in the spinal cord
ganglia
clusters of neurons that function as primitive brains
phylogenetic development of humans
the development of higher species from lower ones
ontogenetic development
the development of the individual human from sperm and egg cells
taxonomy of life
cladogram
shows groups or related organisms as branches on a tree
hominid
(= primate that walked upright)
- was a humanoid species that originated about 5 million years ago
- all humanoid species are descended from this
australopithecus
southern ape
- originated about 4 million years ago in Africa and has a brain size of about 400 cm^3 weighing about 0.4kg
- example of this is australopithecus afarensis called Lucy
homo habilis
handy man
- originated about 1.5-2.5 million years ago in Africa and had a brain capacity of about 800 cm^3 weighing about 0.8kg
- used simple stones as tools and also ate animal foods
homo erectus
erect or upright man
- originated about 1.5 million years ago and has a brain capacity of about 900-1200cm^3 weighing about 1kg
- used better tools than homo habilis and migrated to Europe and Asia
homo sapiens
knowing man (modern humans)
- originated in Africa 120,000 years ago and migrated to Europe 100,000 years ago
- were responsible for the extinction of the Neanderthals and are known for their cave art
- brain capacity of about 1500cm^3 weighing 1.48kg
brain weight over last 4 million years
homo sapiens brain weight is about 3 times the size of an australopithecus brain
- brain weight tripled in about 4 million years
correlation between complex behavior and cerebrum/cerebellum
the larger the cerebrum and cerebellum is and the more folded, the more complex the behavior will be
- in relation to body size
encephalization quotient (EQ)
calculated by dividing the actual brain size by the expected brain size relative to body weight
- humans have the highest EQ of all animals
- cat EQ = 1, australopithecus EQ = 2.5, modern human EQ = 7
counting brain cells
a method to estimate the relative size of the brain
- the higher the packing density, the more complex the behavior
how did the human brain get so big
- drastic climate changes
- lifestyle adjustments
- efficient brain cooling
- life history divided into stages; changed processes at these stages may have cause the size of our brains
lifestyle adjustments impacting brain size
- hunter-gatherer: required complex behaivor
- living in larger social groups
- eating fruit
- use of fire and cooking
efficient brain cooling
human brain has become a lot larger due to better blood circulation
neoteny
the process in which juvenile stages of predecessors become adult features of descendants
larger brain = better brain ?
larger brain does not mean that it is a better brain within the same species
