How does the human brain work?


Specifically when considering the storing of memories

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“If the human brain were so simple that we could understand it, we would be so simple that we couldn’t.”

-George Edgin Pugh

Answer that and go grab your nobel prize because that is one of, if not the greatest mystery of modern medicine.

We have a pretty good idea how the brain works physiologically. A neuron, which is the brain’s main type of cells, produce electrical signals by opening and closing ion channels on their cell membranes. The mechanism is far to complicated for a 5yo, but if you remember middle school science, you can conduct electricity in metals and in solutions with lots of salt dissolved. Neurons produce and conduct impulses (electricity) by opening and closing those channels on their cell walls which in turn allows ions to freely exit or enter the neuron.

Now, let’s group two neurons together. A typical neuron that is taught to kids and HS students, which is called a multipolar neuron, consists of 4 basic parts: neuron body (the central part that keeps the neuron alive), dendrites (which accept impulses from other neurons), axon (which carries the impulse through the neuron and ends with the, axon terminal which connect to the dendrites of other neurons via a synapse.

So if we have a chain of 3 neurons, the impulse will bass through them beween the axon terminal of the previous neuron to the dendrite of the following neuron and so on. This is all in general because there are exceptions, such as axon-body synapses, axon-axon synapse etc.

Now onto how a neuron *works* think of a neuron as a little computer, it can take one of two states: 1. It is actively conducting impulses to another neuron 2. It is not conducting impulses to another neuron. As you can see, just like a computer has on and off (1 and 0), so does the neuron. Then, how does a neuton know if it should be in the on or off state. The answer is EPSPs and IPSPs

While keeping it eli5, the axons of previous neurons which form a synapse with the dendrites of the following neuron, produce EPSPs and IPSPs. EPSP stand for excitatory post synaptic potentials and they nudge a neuron towards its “on” state. IPSPs are inhibitory post synaptic potentiald and they nudge the neurin away from it’s “on” state, so they keep the neuron in its “off” state. Let’s remember that a neuron get’s a lot of impulses from other neurons that give their impulses to it and because those impulses can be excitatory or inhibitory, our little neuron conbines all the EPSPs and IPSPs and checks if the signal is strong enough to flip that neuron to its “on” state.

Think of it like this. Imagine you have a light bulb connected to a lever or a switch, and 10 people pusshing the lever. Now imagine 2 of them pushing the lever to a “on” position, while 8 of them are pushing it towards the “off” position. The lever in this analogy is the neuron. It “combined” all 10 inputs and decided if the two people pushing for “on” are strong enough to overcome 8 people pushing for “off”. If it concludes that they are, the light will shine.

This is the basic of the basics we know. We know a lot more than that, and we suppose that this concept which is not too hard to grasp is the turning wheel that makes uor brain work. All of brain’s functions are, at leats attempted to” being explained by this foncept, just on a larger scale. Truth be told, we still know so little, but day by day, we are finding out mora about the most complicated sack of meat and fat dipped into a salt bath.