80,000 thoughts go through our heads every day but have you ever stopped to think. . .
What are thoughts? And what happens in our brain when we think? This topic was proposed by our patron Brian García.
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com/curiosmente or by clicking the join button in this video. We have to admit that we cannot answer this question so satisfactorily because there are still many questions about how the brain works, but there are many parts of the puzzle that we do know and that we can talk about. Our brain has about 100 billion neuronal cells, about the same number of stars as the Milky Way.
The most abundant neurons are composed of dendrites, the body, an axon, and the axon terminals. Our neurons are like thousands of batteries capable of producing electricity, but unlike a battery, neurons do not produce electricity by the movement of electrons, but by the movement of charged atoms, that is, by ions. At rest, neurons have a positive charge on the outside due to the large amount of sodium ions and a negative charge on the inside due to the large amount of potassium ions.
Well, the truth is that both sodium and potassium are positive ions, but potassium ions are associated with negatively charged proteins and that generates a difference in charges. The voltage differential inside and outside is -65 millivolts. This is how it is in the rest state, as if our battery were turned off by a switch and how does it go from being in rest to being activated?
It is a process that consists of several steps. In the dendrites there are receptors, where neurotransmitters released by other neurons bind . This union causes ion channels to open that allow sodium ions to pass inside, making the neuron more positive.
If enough ions enter so that the voltage inside the neuron changes from -65 to -55 millivolts, even more sodium channels open and the neuron becomes positive. This change in charge is called action potential and acts as an electrical signal that moves through the axon of the neuron, opening sodium channels and making the neuron's path more positive. It's like when the public waves in a stadium!
When the electrical signal reaches the end of the neuron, that is, the axon terminals, the neurotransmitters are released and pass into the synaptic cleft. The neurotransmitters bind to the receptors of the next neuron and the entire process is repeated. As you can see, the chemical signal is transformed into an electrical signal and then back into a chemical signal, although some neurons do not have this change and remain as a rapidly moving electrical signal, as in the case of neurons that control reflexes.
A single neuron is linked to many other neurons through synapses and may be receiving different neurotransmitters from each . Just as there are neurotransmitters that cause sodium channels to open and make the neuron positive, there are neurotransmitters that open channels for the chlorine ion, which is a negative ion, and make the neuron more negative, preventing the neuron from activating. In a very simplified way, it is something similar to the ones and zeros of the binary code of computers, where the ones are an electrical pulse and the zeros are the absence of it and the combination of numbers is what forms the instructions.
The difference is that we have many neurotransmitters and each neuron is receiving different instructions. The electrical activity of clusters of neurons creates repetitive, rhythmic, and synchronized frequency patterns known as brain waves. These oscillations apparently facilitate communication between neurons and have been seen to be regulated by some neurotransmitters.
So far we distinguish 5 main types of patterns according to their frequency and amplitude: alpha, beta, gamma, delta and theta. Different brain waves have been linked to different states, e. g.
When we are asleep, delta waves predominate, while when we are wandering, theta waves are usually more present. More recent studies detected alpha waves in the prefrontal cortex when thoughts jump from one topic to another. Anomalies in these oscillations also allow us to diagnose epilepsy and other diseases.
The curious thing is that, although these patterns are similar even between species, they are also very different between one individual and another and it is even believed that they are almost as unique as a fingerprint. Neurons are interconnected and form circuits or “pathways”, some of these paths function as “highways” carrying electrical impulses to different parts of the brain quickly. These roads and highways are important in the functioning of the brain and are related to neural networks.
We know that there are certain neural networks that turn on depending on the activity we are carrying out, for example: the default neural network is the one that turns on when we are thinking about the future, or simply when our mind is wandering. There is also a control network, another of salience, another of attention, another motor and another visual. Well, very complicated and all, but what does this have to do with thoughts?
Well, everything: our perceptions, feelings, emotions, memories and thoughts arise from our neural activity. The difference is that a perception is associated with a stimulus and it is easier to see how and where it is processed in our brain. The way we convert electrochemical signals into language, symbols and thoughts is not so clear.
Some believe that thoughts are the retrieval of a large number of memories. But, if we kept a brain alive in a laboratory, although it would be capable of thinking, the thoughts would not correspond to reality. So other people believe that in addition to the brain, it is our body and the world around us that allow us to form thoughts.
People with Botox, who cannot gesture as much, even if their brain is functioning well, take longer to perceive sadness and annoyance in other people. In another study, different people were asked to determine how steep a hill was just by looking at it from below. People with better physical condition saw it as less steep than those who did not exercise or who had been given a heavy backpack.
With these experiments we can see how our body influences our thoughts. And is it possible to read thoughts? Since thoughts are represented in a spatial dimension, it might become possible to read them.
Since 2011 we have been working on decoding mental images. First, a person observes different images and the brain activity is recorded through an MRI, then only with the information obtained from the MRI they try to recreate the images. Until now, videos, photographs and even some dreams have been recreated in a very simple way .
It has also been possible to translate neuronal oscillations into words with a 40% success rate. We are still quite far from reading people's minds and even more so because the “algorithm” with which each person thinks varies a little, but the small advances are impressive. Curiously!
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