Metaphors, Analogies, and Schemata
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METAPHORS
Microglia are the 'Vacuums' of the Brain
Microglia are ‘vacuums’ that suck up all of the debris and waste floating around after neuronal cells die or in the presence of foreign bodies and infection. When your brain is dirty, the microglia vacuum it up for you so that you don’t get sick!
Antidepressants are the 'Food Stamps' of the Brain
Antidepressants allow someone who does not have the adequate ‘funds’ of serotonin, dopamine, and/or other neurotransmitters to function better by providing them with a pass to have more neurotransmitters become available. However, antidepressants, like food stamps, are often not equal to what the average American has or eats on a daily basis, although they do help.
ANALOGIES
Adenosine and the Urge to Sleep
Adenosine blocks the release of neurotransmitters essential to your daily functions. The more adenosine you have, the less neurotransmitters get released, thus the greater the urge to sleep becomes.
You can think of this as the daily cycle of a cell phone. Your body is the ‘cell phone’. Your ‘app usage’ is the adenosine level in your body. Your ‘battery’ is charged with neurotransmitters.
In the morning, you have just woken up and have not gotten a chance to check your phone yet. You have little-to-no adenosine, and plenty of neurotransmitters are getting released, so your phone battery is fully charged. Then, as you go through your day, your app usage increases, causing you to drain your battery, or essentially, have fewer neurotransmitter-receptor interactions.
At some point, you start to have ‘low battery’, and you get more and more warnings until you absolutely have to recharge to continue using your phone. The warnings serve as your increasing urge to sleep that becomes more and more unquenchable as your battery drains. In order to keep your phone (your body) active, you must recharge (and to recharge means you have to sleep).
Neural Networks as a State
The brain is a state that holds many counties with even more towns, and even more people.
Your brain regions are ‘counties’, your neurons are ‘towns’, their axons are the ‘highways’, and the synapses are the ‘interchanges’ that allow people to move around the county to get to their destinations.
People are the neurotransmitters that drive the motivation for the towns, counties, and state to fully operate. They move in vesicles (or ‘cars’) with purpose, as a result of other people’s interactions and their actions have consequences and set off reactions in other towns.
Eventually, people’s movements and actions cause changes and growth for their county, and slowly, the brain-state gains history, adapts, and grows.
SCHEMATA
Myelinated versus Unmyelinated Axon Speeds
Think of myelinated and unmyelinated axons as different cars.
A car, no matter what brand, will serve the same purpose of getting you from one destination to the other, just like an axon will transport an electrical signal down to the next destination.
However, the speed at which an axon does this is very important because it creates different effects in the body and leads to different reactions. A myelinated axon can be thought of as a fancy Ferrari, while an unmyelinated axon, a Honda Civic.
Both will take you home from UCSB, but the Ferrari, if unrestricted by government speed limits, would get you there much faster, because the engine is made with extra features that make it stronger and allow it to be about ten times faster than a Honda Civic.
This is much like a myelinated axon; myelin is the ‘extra feature’ that propels the electrical signal forward at about ten times the speed in milliseconds. So, unmyelinated axons still perform the same task, but because they lack the myelin, they reach their destination in about one-tenth the time of a Honda Civic.
IPSP's
EPSP's
EPSP’s and IPSP’s are like ‘money’ and ‘taxes’, respectively.
The more ‘money’ you have, the more you can do with it, but ‘taxes’ take away from that. You are trying to raise enough ‘money’, or have enough excitation, in your ‘business’, or in your neuron, to go on a ‘trip to Paris’, or fire an action potential.
EPSP’s and IPSP’s in a neuron come from multiple locations. Let’s say you are running a ‘business’ (this is your neuron), and each EPSP is a ‘client’ who is paying you. The more ‘clients’ you have, the more money you are earning, and the more likely you will be able to spend it on a ‘trip to Paris’. Your ‘trip to Paris’ is the firing of an action potential.
However, while EPSP’s are coming to your business (or, ‘neuron’), IPSP’s are also coming in. So that, in effect, is ‘taxes’. They regulate how much money you actually earn by taking some of it (or, giving you negative money).
So, if you add the amount of ‘money’ you make and subtract it by the amount that taxes take away from you, you get your net earnings. If your net earnings reach a certain ‘total goal amount’, you are able to use that ‘money’ and go on a ‘trip to Paris’!
Same with your neuron: the net total of your EPSP’s (positive, excitatory electrical potential) and IPSP’s (negative, inhibitory electrical potential) dictates whether your neuron will reach threshold, and fire an action potential, allowing it to reach its destination and communicate with the next neuron.