Every second that passes, including this one, your central nervous system is the laboratory for millions of chemical reactions, which you, moreover, are not even aware of. They are the language used by the brain to receive, process and transmit information.
The brain has long been thought of as a machine. Since every idea is the daughter of his time, René Descartes had compared it to a hydraulic pump, Sigmund Freud to a steam engine, Alan Turing to a computer. As you can well imagine, Turing is the closest to it. The brain is not exactly a computer, but the analogy between the two is undeniable.
Both transmit information by means of electrical messages. It is true that in the computer, messages are digital (expressed in the binary mathematics of zeros and ones) and in the brain, analog (expressed in a varying arc of millivolts). But the question is more complex, because if the sum of the analog messages exceeds a certain level, the neuron "fires" and transmits an electrical impulse to the connected neurons. If, on the other hand, the level is not passed, nothing happens. This too is a binary message: yes or no, on or off.
Both calculate. But if the computer has a serial structure, i.e. it calculates according to a pre-ordered sequence, the brain operates in parallel mode, performing a large amount of calculations simultaneously. On the other hand, microprocessors for graphics applications (called GPUs) already adopt a parallel technology.
Both need energy: the computer in the form of electrons, the brain in the form of oxygen and glucose.
Both have expandable memory: the first just needs to add or replace memory banks made of silicon, the second just needs to multiply the synaptic connections through study, exercise and repetition.
Both have evolved over time: the computer at an exponential rate, doubling its calculation capacity every two years, while the brain of Homo sapiens - originating from the primitive brain of primitive invertebrates - took 500 million years and, in the last 50 thousand, not much has changed. In fact, it is the same basic model that you, dear users, are equipped with.
For centuries and millennia it was believed that the human brain - with the exception of the childhood period, when we learn to talk and walk - was essentially static and unchanging. That physical damage to the brain was impossible to repair, not even in part. That a boy behind in his studies had to deal with insurmountable cognitive limits, thus fueling generations and generations of social inequalities. It was believed that bad habits and addictions were burdens to be carried through life, or that a person of eighty could not keep the memory of one of fifty.
Instead, only since the XNUMXs have we discovered that the opposite is true: the brain is constantly changing. Indeed, change is at the very basis of its mechanisms. The effects of this property, also called brain plasticity, go beyond imaginable. The brain is a powerful computer, asynchronous and parallel but which, moreover, is capable of re-adapting its own hardware by itself.
The brain hardware, basically made up of ingeniously arranged atoms and molecules, packs some 86 billion neurons into a 200-pound brain. Since each neuron can fire and flood thousands of adjacent neurons with signals up to 38 times per second, some have estimated that the brain can perform up to 10 trillion operations per second. That story that humans only use 13% of their brains is total nonsense. But the beauty is that it manages to do all this, consuming not even XNUMX watts/hour. No supercomputer in the world can yet beat the calculation capacity of a human brain (consider that sight, hearing or imagination are also "calculations") let alone its extraordinary energy efficiency. And this is only the beginning.
Almost all cells of the human body are born and die, incessantly. All but the neuronal cells, the only ones that accompany her along the path of existence, from the first to the last day of her life. After all, they are the ones who produce what you are. Personality, skills and talents, erudition and vocabulary, inclinations and tastes, even memories of the past are somehow written into the personal neural architecture. So personal that there is no brain in the world like yours, even if you had a twin or a twin.
Well, the aforementioned machine is even able, within certain limits, to correct the defects of its hardware. When an area of the brain is accidentally damaged, the brain is often able to reprogram itself, move missing links elsewhere, and essentially fix itself. And while this sometimes happens on a large scale (as in the case of vision loss, when unused brain areas serve other senses), it happens all the time on a small scale because, with aging, many neurons die and never come back. . But the neurons left alive know how to reorganize themselves so that advancing age has no fatal consequences. Don't tell that to a silicon processor, where one bad transistor can bring the whole thing down.
However, when it comes to reorganizing the synapses, the estimated 150 trillion connections between neurons, the brain does not need to face an emergency. It does it by itself, spontaneously.
The influence of one neuron on each of the hundreds of connected neurons can be very strong, very weak, or anywhere in between, depending on the strength and strength of each synapse. There is also a sort of rule, enunciated by the Canadian scientist Donald Hebb, in 1949: «Neurons that fire together, wire together». Neurons that fire together pair up and strengthen each other's bond. This is how the brain continuously reorganizes itself: creating new synapses, strengthening old ones, cutting off those that are no longer needed. A large number of brain functions, starting with learning, depend on this constant adjustment of synaptic connections and their strength, solidity.
In short, contrary to what has been believed for centuries, the human brain is anything but static and immutable:
* in some cases it is able to repair itself;
* any "back in school" child can learn to learn. Just teach him how to do it and, instead of mortifying him, encourage him;
* any bad habit, however unpleasant or venial it may be, can be abandoned. Even a serious addiction, such as acute gambling addiction, can be controlled and subdued;
* an elderly lady can keep the memory of a young adult, if she doesn't stop learning and brain effort;
* on the contrary, even a condition of prolonged stress, or even a post-traumatic stress syndrome, produces unwanted and long-term changes to the brain connections.] Attention: in some cases, an imperfect functioning of the brain machine can imply pathologies or other unwanted responses that are beyond the reach, merely informative, of this manual and that require advice and care from specialized professionals.
The user of a functioning brain can discover that, almost always through a volition – an act of will – he is able to modify, adjust, tune at least in part his own synaptic configuration. Which then, in a nutshell, means one's life.
Waiting to meet some alien of superior intelligence, the brain of Homo sapiens remains the most complex, amazing and fantastic thing in the universe.
It is the complexity that makes those neurons capable of producing thought, intelligence and memory, all tailor-made for each user. It is astonishing that such a biological machine still vastly surpasses all the machines in the world in terms of calculation capacity and efficiency. It's great to walk around.
