Brain Basics Flashcards
who was Phineas Gage?
- iron fired like a missile into and out of his head
- went from being efficient, capable, energetic, and persistent to… sporadic, disrespectful, inappropriate, indulgent, impatient and impulsive
- had a radical change in personality, but changes may have been temporary
developed severe epilepsy which was ultimately his cause of death
what are the two schools of thought regarding the brain?
- doctors - the head is the seed of your intelligence and personality
- philosophers - the heart is the source of your personality/spirit
what was the egyptian perspective on intellect and the brain?
- didn’t give much credit to the brain, thought the heart was the seed of intellect
- preserved all organs, especially the heart, but disposed of the brain
what were the different greek perspectives on intellect and the brain?
- hippocrates - notable doctor, saw that patients with head injury had problems with emotion, memory, cognition (head is the seed)
- aristotle - philosopher, thought that the brain cooled or heated the blood which results in our emotions (heart is the seed)
what was the roman perspective on the brain and intellect? who did it come from?
- Galen
- saw that humans and other animals have the same basic anatomical layout, started dissecting animals, sometimes alive
- cerebrum and cerebellum - galen noticed a big brain (cerebrum) and little brain (cerebellum), assumed cerebellum was used to control muscle because its hard and that cerebrum was for memory because it’s soft
- ventricles and nerves - noticed holes with fluid (ventricles) and tubes (nerves), thought that our thoughts were in the fluid and controlled our body by moving through nerves
- humours (fluids) - noticed the brain was full of fluid and thought that our thoughts are in them
what did Vesalius discover and when?
- 18th century
- vesalius was known for dissecting the human brain and mapping the anatomy
- noticed darker and lighter parts of the brain, ventricles, gyri and sulci are consistent in different people
what did Descartes discover and when?
- 18th century
- descartes was fascinated by hydraulics - how pushing a fluid through a tube activates areas (a → b → c)
- thought that fluid moving in the body controlled our reflexes
- we are a series of biological mechanisms
- descartes thought all organisms were clockwork mechanisms except humans because we have a soul
- only have one pineal gland, so he thought that was where our soul is
what is materialism in science?
- have to assume that everything in the universe is physical, either matter or energy
- it can all be physically observed and correspond to physical laws (cause and effect)
- thoughts are physical, memories are physical, emotions are physical
in the 19th century, what was the connection between wires/electricity and the brain?
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wires/electricity - galvani and du bois-reymond thought that the brain worked through electricity
- if you put the brain in water, there is an electric charge
- they took half of a frog and connected to wires and ran a current through it and the leg muscles moved
- showed us that the brain is connected to the body through wires and sends message down and up to control
how did bell and magendie think neurons and wires differ?
- bell and magendie found that our nerves and neurons are not wires but are similar
- damaged the spinal cord on the dorsal or ventral sides
- when damaging the dorsal side, they lose sensory inputs
- when damaging the ventral side, they lose motor output
- we carry electricity but the “wires” only move one direction
who discovered the localization of brain function and when?
fluorens, gall, and broca discovered the localization of function in the brain in the 19th century
- fluorens - deliberately damaged cerebellum to see motor coordination problems, proved localization of function
- broca - patient could only say “tan” but seemed to comprehend conversation well, after he died they saw that one part of the left frontal lobe was damaged, showed us where is responsible for speech (broca’s area)
- gall - noticed that peoples’ heads and skulls were different sizes, looked at bumps of skulls to determine the shape of the brain which he thought tells us about a person’s personality
what were the two main biological insights from the 19th century?
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evolution - darwin recognized the mechanisms of evolution
- slight differences show us slight advantages and disadvantages which make us more or less likely to survive
- tells us all aspects of psychology are evolutionarily useful (like emotions)
- tells us we all have common ancestors so we can investigate animal models to represent the human brain
- slight differences show us slight advantages and disadvantages which make us more or less likely to survive
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cellular theory - schwann found that the base unit of life is a single cell
- neurons in the brain tell us the story, not the whole nerve
who was Golgi and what did he do/believe? when was he prevalent?
- late 19th and early 20th century
- golgi mixed silver nitrate and created the golgi stain, showing us a neuron for the first time
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reticular theory (golgi) - neurons are interconnected and continuous like tubes and the net as a whole is the base unit of the brain
- claimed electricity could move back and forth
- went against schwann by saying that the brain is special and the reticulum is the base unit
who was Ramon y Cajal and what did he do/believe? when was he prevalent?
- late 19th and early 20th century
- Ramon y Cajal used the golgi stain and reproduced what he saw in the microscope as drawings
- noticed a variety of types of cells, the ones in the cerebellum and cerebrum look different
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neuron doctrine (ramon y cajal) - base unit of the nervous system is the single neuron, some of the branches the neurons are input layers and others are output layers
- said they were discontinuous and had a gap (synapse)
who was right, Golgi or Ramon y Cajal?
- ramon y cajal and golgi shared the nobel prize but they did not like each other
- ramon y cajal was proven right with the discovery of the electron microscope
- golgi wasn’t entirely wrong, sometimes the cells in the nervous system work like a reticulum
what discoveries/technological advancements were made in the 20th century?
- modern neuroscience was born
- structural MRI - showed us the brain without damaging it
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brain bow mouse - took a gene of a jelly fish and made variations in different colours, gave them to different cells and each of them express different amounts
- allows us to see neurons densely packed together
- two photon microscopy - animal exposed to light for the first time, dendrite in the visual cortex grew and changes
what metaphor do we use for our brains today?
Today’s Metaphor: The Computer
* binary is chosen for computers because of neurons
* neurons either fire, or don’t fire
* neuroscience and psychology love computer-related terms like “processing” “information” “wiring” “coding”
* this can lead us to more problems since the words we use aren’t completely accurate
* computers represent information while the brains construct information
what is modern neuroscience?
- the study of the nervous system
- ultimately is the study of human nature
- goal is to learn how the nervous system functions, and how it relates to the mind
what are the levels of analysis in modern neuroscience?
- molecular neuroscience
- cellular neuroscience
- systems neuroscience
- behavioural neuroscience
- cognitive neuroscience
what are some human brain facts?
- 2-3% of body weight (~3lbs) but consumes about 20% of your energy
- slightly larger in men than women
- composed of neurons, glia, stem cells, blood vessels
- less than 100 billion neurons, more than half are in the cerebellum
- consistency of soft tofu
- convoluted (wrinkled)
- cells are not replaced, once they die they are gone
what is adult neurogenesis? does it happen?
- adult neurogenesis is the creation of new cells to replace the other ones
- historically didn’t see evidence of adult neurogenesis in humans
- subregion of hippocampus may be the only area of adult neurogenesis
- then we found that hippocampal neurogenesis happens only until 13 years old
- so, adult neurogenesis does not happen
- if it does, it’d be a very small undetectable amount in a subregion of the hippocampus
- cells may change shape or form, but we don’t get any new ones
what part of our brains are related to intelligence?
- more convolutions → more intelligent
- bigger forebrain → more intelligent