You’re reading a guest blog post by Manuel Rico Fernández San Silvestre, a summer intern in the Sahay Lab at Massachusetts General Research Institute.

Science goes beyond data, and thus, scientific progress isn’t achieved just by the accumulation of results.

A long time ago, celestial bodies were thought to draw perfectly shaped circles when orbiting around the Earth, which was then believed to be the center of the universe. 

While trying to defend this geocentric model, early scientists came up with the concept of epicycles, a (subsequently disproved) theory to overcome observations that objects in the sky changed in size as a result of increasing or decreasing distance from the earth. 

It wasn’t until Galileo built his first telescope that the idea of the sun as the center of the universe began to gain acceptance.

Kepler, a contemporary of Gallileo, overcame the epicycles issue by proposing an ellipse-shaped orbit, consolidating the idea that the Earth orbits around the Sun. 

In order to understand scientific breakthroughs, it might be convenient to bring the concept of “paradigm” to the table, which is the general body of knowledge (theories, frameworks, etc.) that have been adopted by the members of a given scientific community. 

Thomas Kuhn, a philosopher of science, believed that scientists who try to explain the world in terms of the prevailing paradigm are just doing “normal science.” 

However, they will unavoidably end up facing issues that will eventually lead to a period of “crisis” that is only solved once a new paradigm is established. Researchers who work to establish this new framework constitute a “scientific revolution.”

Another way of thinking about this concept might be to think of scientific frameworks as two parts:  a hard core that holds the fundamental principles of a paradigm, and a protective belt that includes auxiliary hypotheses aiming to defend it against critics⁸.

In this case, the scientists who introduced the concept of epicycles were creating a protective belt to defend the concept of geocentrism from critics.

Those scientists who stated that the sun—and not the Earth—is the center of the universe contributed to the scientific revolution by replacing the hard core of the framework.

The Journey Towards the Neuron: Reticular Theory vs. Neuron Theory

A similar evolution in thought can be seen in our understanding of neurons—the brain cells that are working as you read this to process and understand the article.

Although in modern times it is widely known that neurons are individual cells that connect to one another by releasing molecules called neurotransmitters into the synaptic cleft, the acceptance of this knowledge was not immediate.

Understanding the structure of our nervous system was the first step toward modern neuroscience, and required the development of various staining methods.

Camilo Golgi and the Reticular Theory

Part of this journey started in 1873 when Camilo Golgi, an Italian biologist, developed his black reaction, in which he submerged a block of nervous tissue in silver nitrate after hardening it in potassium dichromate.

Individual neurons could then be seen as black cell bodies with prolongations called dendrites and axons. 

Golgi’s work led to the development of the reticular theory, which posited that the nervous system was composed of a continuous system of cells without gaps. 

Santiago Ramón y Cajal and the Neuron Theory

In the 1880s, Santiago Ramón y Cajal, a Spanish histologist who was fascinated by Golgi’s work, decided to use Golgi’s method to study different nervous system structures, adding detailed explanations of previously undescribed elements.

Although the observed specimens were the same for both Cajal and Golgi, the observer was different, and this made all the difference.

By modifying Golgi’s staining process and studying sections of mammalian and avian brains, Cajal brilliantly suggested that neurons were individual elements separated by a gap that later named a synapse. 

This irreconcilable difference in scientific findings led to one of the most intriguing discussions in biological sciences, and this discussion, dear reader, laid the foundations of contemporary neuroscience.

Making the neuroscientific community realize that the sharp membrane protrusions that could be observed in Golgi’s staining were dendritic spines —branches extending off of dendrites— and not a staining mistake was Cajal’s biggest challenge in consolidating the neuron doctrine 

It wasn’t until he was able to develop his own staining technique that the so-called dendritic spines gained the vast majority’s acceptance^5,10.

Cajal worked on the revolutionary side of science and was finally able to convince his contemporaries that the neuron doctrine was correct after it was visibly demonstrated years later through a process called electron microscopy. 

But his detractors stubbornly resisted adopting the theory.

Golgi still tried to defend the reticular theory when he and Cajal shared the 1906 Nobel Prize in Physiology and Medicine, at a time when the neuron theory was already broadly accepted. 

The Path to Scientific Breakthroughs

This post aims to convey one simple but vital idea: scientific breakthroughs happen because of passion and resilience.

Operating on this side of science is only possible when personal strength is accompanied by an ecosystem that leverages scientists’ confidence. 

Having a high concentration of revolutionary researchers working hand-in-hand and surrounded by the resources they need to make scientific advances is essential if we aim to make an impact in people’s lives, particularly when we are talking about biomedical research.

Science isn’t just data, and the truth isn’t acquired just through results.

Is it the vast majority that sets what’s true? Or is it the truth that is waiting to be proven?

References

1. Bentivoglio, M., Cotrufo, T., Ferrari, S., Tesoriero, C., Mariotto, S., Bertini, G., … & Mazzarello, P. (2019). The original histological slides of Camillo Golgi and his discoveries on neuronal structure. Frontiers in neuroanatomy, 13, 3.

2. Camilo Golgi Nobel Lecture: https://drive.google.com/file/d/1xsY6yw76oA6zW36UJvaixxRSUkDweqB3/view?usp=sharing

3. Castro, P. S. (2011). Cajal y el vuelo de las «mariposas del alma»: los orígenes de la neurociencia moderna.

4. Chalmers, A. F. (2013). What is this thing called science? Hackett Publishing.

5. Glickstein, M. (2006). Golgi and Cajal: The neuron doctrine and the 100th anniversary of the 1906 Nobel Prize. Current Biology, 16(5), R147-R151.

6. Grant, G. (1999). How Golgi shared the 1906 Nobel Prize in physiology or medicine with Cajal.

7. Kuhn, T. S. The structure of scientific revolutions.

8. Lakatos, I. The methodology of scientific research programmes. 9. Santiago Ramón y Cajal Nobel Lecture: https://drive.google.com/file/d/1c2pk-3EEuC6pXdAY_LdkcGPL3NNyv_9m/view?usp=sharing

10. Santiago Ramón y Cajal, S. R. (1896). Les épines collatérales das cellules du cerveau colorées au bleu de méthylène.