In the history of science we find two types of scientists. On the one hand, those like Thomas Alva Edison, inventor of the light bulb and electric lighting, or Alexander Fleming, who discovered penicillin, which saved countless lives. On the other, scientists like Albert Einstein or Charles Darwin, whose respective works on relativity or natural selection are of a more theoretical nature and, therefore, less comprehensible to ordinary people. The latter were basic scientists, that is, thinkers interested in knowing the deep causes of natural events, in knowing not only how but also why things that happen in nature happen.

Technological knowledge, of immediate applicability, is always more popular than basic knowledge, which does not mean that it is more important. In fact, it could be the opposite, because without Einstein’s work, nuclear technology would hardly have been developed, also applicable to the cure of cancer, and without Darwin’s work, it would have been more difficult to advance in the development of biological science and technology. . Basic or fundamental science is necessary to understand nature and be able to control or modify it for the benefit of our species.

So what kind of scientist was Santiago Ramón y Cajal? An inventor or discoverer, like Thomas Edison or Alexander Fleming, or perhaps a basic and theoretical scientist like Einstein or Darwin, interested in explaining how natural processes occur?

The answer is simple, because the Aragonese had all the ingredients of genius: he was an inventor and discoverer, but also, above all, a great thinker, one of the greatest theoretical scientists of all time. Accustomed as we are to seeing him photographed in front of his microscope’s eyepiece, we might think that his main task was to spend hours and hours in that state and make visual discoveries about the materials he observed. But that wouldn’t make him a genius. His greatness is not in seeing what he saw, but in intuiting what he was able to deduce from it, without the techniques available at the time allowing it.

When he began his medical studies at the University of Zaragoza, over a century and a half ago, very little was known about the formation and functioning of the nervous system. Entering his office was like entering a dense and unknown jungle, because when looking at any portion of nervous tissue under a microscope, what was seen was a confusing and at the same time fascinating tangle of intricate and complex structures. Camillo Golgi, an Italian scientist, discovered an important technique for staining this tissue and making its individual components more visible under the microscope. His observations and those of other scientists at the time led him to believe that the nervous system was like a mesh or net of an infinite number of fibrous elements extending one after the other. Ramón y Cajal was introduced to this method of staining Golgi cells in Valencia by Luís Simarro, also a neuroscientist and psychologist (immortalized by Sorolla in one of his paintings). He improved it and applied it to the nervous tissue of different animals.

What kind of scientist was Santiago Ramón y Cajal? The Aragonese was an inventor and discoverer, but also a great thinker

Madrid, 1920. Scientist and Nobel Prize winner Santiago Ramón y Cajal works in his laboratory at the Faculty of Medicine, on Calle de Atocha.VIDAL

The observations that Ramón y Cajal made were motivated by his obsession with knowing not only the shape and structure of the nervous system, but also its functioning. Skillfully, he perfected Golgi’s method and applied it to the tissue of bird embryos, when the brain is still being formed, and the conclusions he arrived at were different from those of the Italian, because from his own observations he intuited that, although very restricted and invisible even under the microscope, between cell and cell there would be a real space, in such a way that the nervous system, far from being a network, would be constituted by billions of individual cells very close to each other, although separated, communicating by contact and not by continuity. It was his precise approximation of what would later be called “synapses,” the tiny gaps through which one neuron communicates with another.

One of Ramón y Cajal’s most surprising scientific moments took place in London, in March 1884, when he was invited by the Royal Society (one of the most prestigious scientific societies in the world) to deliver the Croonian Lecture, its main annual conference on biology. There, before an audience of eminent scientists, he postulated that learning could result from an enrichment of the neural connections between neurons and the sprouting of new shoots and even new endings in brain cells. “Intellectual power,” he said, may depend not so much on the size or number of brain cells as on the connections between them, on the richness of the connective processes. Although these were very bold and difficult to test hypotheses at the time, they dazzled European scientists. It was the first time that someone intuited and dared to propose what can happen in the brain so that we can learn and remember.

In 1884, Ramón y Cajal postulated in London, at the invitation of the Royal Society, that learning could be the result of nervous connections between neurons, not so much the size of the brain.

Ramón y Cajal had arrived at these conclusions after observing the buds or spines that arise from neurons, and he reasoned that these buds, which he called dendritic thorns (today we call them simply dendrites), since they reminded him of the thorns of rose bushes, could be elements needed to form new connections when learning or performing intellectual exercises. Camillo Golgi, with whom Ramón y Cajal shared the Nobel Prize in 1906, thought differently, believing that the dendritic spines discovered by Cajal were nothing more than artifacts or optical defects in the rudimentary microscopes of his time. As artificial intelligence makes clear, a brain structured in the form of a network could never have the capacity of a brain formed by individual cells interconnected in a complex way where each connection between them, each synapse, works as a small subordinate decision center and combined with the 10¹⁴ interconnections between neurons that can be found throughout the human brain.

Ramón y Cajal was on that track and he wasn’t mistaken, but it took a while to confirm and he was clearly recognized. In 1944, ten years after his death, Rafael Lorente de Nó, one of his most distinguished disciples, published in the United States an important scientific work in which, in line with his master’s postulates, he stated that the brain contains numerous circuits. neurons reciprocally interconnect with each other. This work was decisive for another great neuroscientist, the Canadian Donald Hebb, to postulate “associative plasticity”, a mechanism that allows neurons to modify their morphology and metabolism based on their activity, making them more powerful to communicate with each other. and produce mental functions. Just as physical exercise modifies an athlete’s muscle mass, the Canadian scientist thought that the recurrent neural circuits proposed by Lorente de Nó based on the ideas of Ramón y Cajal could serve to increase the activity of neurons, altering their functioning and enhancing their efficiency .

Pedro Duque, former Minister of Science, inaugurated an exhibition on Ramón y Cajal in 2020 at the National Museum of Natural Sciences.KIKE TO

And he was right, because that was exactly what the Norwegian Terje Lomo and the British Timothy Bliss verified in 1973 after stimulating the neurons of the hippocampus with weak electrical currents of high frequency (a region of the brain highly involved in memory formation). of anesthetized rabbits. Because the potentiating effect was achieved quickly and could last for weeks, these researchers thought that the long-lasting changes that occurred in neurons in this way, called long-term potentiation, might help the brain store memory. The scientific team of another Nobel laureate, the American Eric Kandel, upped the ante by looking at the electrical and chemical changes that occurred in the neurons of the sea slug Aplysia californica when the animal learned and remembered simple behaviors. In this way, they verified, as Hebb postulated, that learning increases the response of neurons and their interconnections, and that this increase is the result of a series of very precise chemical changes within cells.

It was these chemical changes revealed by American scientists that generated the appearance of the neural buds or thorns that Ramón y Cajal proposed in London in his historical croonian lecturer? It certainly was. On May 6, 1999, Naturefor many the first scientific magazine in the world, gave the following news:

About 100 years ago, Santiago Ramón y Cajal proposed that the neural substrate for learning and memory was the strengthening of connections, or even the formation of new connections, between nerve cells. We now have definite confirmation that such a thing occurs. Formation of new spines was observed after long-term potentiation and this should tell us a lot more about how the brain stores information permanently.

What Cajal intuited could then be seen directly at the Max-Planck Institute for Neurobiology, in Munich, by scientists Florian Engert and Tobias Bonhoeffer, thanks to the use of sophisticated microscopy techniques that showed the emergence of new spines in the stimulated neurons. of the hippocampus: it was the definitive confirmation of Ramón y Cajal’s postulates on the plasticity of the nervous system and memory. The spikes, in short, were not optical defects as Golgi believed. The Aragonese scientist knew this before anyone else, but that was not all, because from his microscopic observations he also intuited the place where neurons receive (the dendrites) and send (the axon) the information they process, and he imagined that neurons targets they could release chemicals that attract and guide the formation of connections, helping neurons find their way as the nervous system forms in embryos.

Almost everything Ramón y Cajal proposed has been confirmed in experiments and observations with modern technology. It even fueled thoughts that are still beyond us today, such as the possibility that the glial cells that accompany neurons in the brain also participate especially in mental processes, something we have already begun to verify. Great scientists are ahead of their time in understanding the phenomena they study. Santiago Ramón y Cajal was at least a century ahead of his contemporaries in understanding the structure and functioning of the nervous system.

gray matter it is a space that tries to explain, in an accessible way, how the brain creates the mind and controls behavior. The senses, motivations and feelings, sleep, learning and memory, language and consciousness, as well as their main disturbances, will be analyzed in the conviction that knowing how they work is equivalent to knowing ourselves better and increasing our well-being and our relationships with other people.

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