Santiago Ramón y Cajal

File:Santiago Ramón y Cajal.png

Santiago Ramón y Cajal.

Santiago Ramón y Cajal (May 1, 1852 – October 17, 1934) was a Spanish histologist and physician who (along with Camillo Golgi) won the Nobel Prize in Physiology or Medicine in 1906 for establishing the neuron (or nerve cell) as the primary structural and functional unit of the nervous system. Ramón y Cajal’s proposal that neurons were discrete cells that communicated with each other via specialized junctions, or spaces, between cells, became known as the neuron doctrine, now one of the central tenets of modern neuroscience.

To observe the structure of individual neurons, Ramón y Cajal used a silver staining method developed by Italian anatomist Camillo Golgi, who supported the prevailing view of the time that the nervous system was a reticulum, or a connected meshwork, rather than a system made up of discrete cells. Convinced that the brain needed independent neurons to function, Ramón y Cajal persisted, modifying Golgi's technique until he obtained clear pictures of distinctly bounded nerve endings.

Ramón y Cajal’s beautiful and meticulously rendered drawings of neurons are still used in textbooks today.

Although he became one of the founders of neuroscience, as a young man Ramón y Cajal wanted to be an artist, and vision would play a central role in his scientific contribution. Ramón y Cajal felt the most essential quality of a scientist was the ability to see clearly: according to Cajal, Golgi was actually seeing separate cells when he looked at the stains, but believed he was seeing a net because he fell prey to suggestion (Otis 2001).

Ramón y Cajal’s artistic leanings extended to the writing of fiction: one year before receiving the Nobel, he published a science-fiction collection called Vacation Stories (Cuentos de vacaciones) under the pen name Dr. Bacteria. Tackling issues of ethics in science as well and challenging established views on organized religion and social class, the stories indicate a scientist engaged with the larger social and ethical questions of scientific discovery.

Contributions to neuroscience

Ramón y Cajal in the lab.

Before the neuron doctrine was accepted, it was widely believed that the nervous system was a reticulum, or a connected meshwork, rather than a system made up of discrete cells (Kandel et al., 2000).This theory, called the reticular theory, held that neurons' somata (later identified as the bulbous ends of individual neurons) mainly provided nourishment for the system (DeFelipe, 1998). Even after the cell theory was postulated in the 1830s, most scientists did not believe the theory applied to the brain or nerves.

The initial failure to accept the doctrine was due in part to inadequate ability to visualize cells using microscopes, which were not developed enough to provide clear pictures of nerves. With the cell staining techniques of the day, a slice of neural tissue appeared under a microscope as a complex, tangled web and individual cells were difficult to make out. Since neurons have a large number of neural processes, an individual cell can be quite long and complex, and it can be difficult to find an individual cell when it is closely associated with many other cells.

Thus, a major breakthrough for the neuron doctrine occurred in the late 1800s when Ramón y Cajal used a technique developed by Camillo Golgi to visualize neurons. Golgi's method is a nervous tissue staining technique discovered by Italian physician and scientist Camillo Golgi (1843-1926) in 1873. Golgi found that by treating brain tissue with a silver chromate solution, a relatively small number of neurons in the brain were darkly stained.

The cells in nervous tissue are densely packed and little information on their structures and interconnections can be obtained if all the cells are stained. Furthermore, its thin filamentary extensions—the axon and the dendrites—are too slender and transparent to be seen with normal staining techniques. The Golgi stain is an extremely useful method for neuroanatomical investigations because, for reasons unknown, it stains a very small percentage of cells in a tissue, so one is able to see the complete microstructure of individual neurons without much overlap from other cells in the densely packed brain.Golgi's method stains a limited number of cells at random in their entirety. The mechanism by which this happens is still largely unknown.

Based on his stains, Golgi concluded that nervous tissue was a continuous reticulum (or web) of interconnected cells much like those in the circulatory system.Using Golgi's method, Ramón y Cajal reached a very different conclusion. He postulated that the nervous system is made up of billions of separate neurons and that these cells are polarized. Rather than forming a continuous web, Cajal suggested that neurons communicate with each other via specialized junctions called "synapses", a term that was coined by Sherrington in 1897. This hypothesis became the basis of the neuron doctrine, which states that the individual unit of the nervous system is a single neuron. Electron microscopy later showed that a plasma membrane completely enclosed each neuron, supporting Cajal's theory, and weakening Golgi's reticular theory.

A human neocortical pyramidal neuron stained using the Golgi technique.

For their technique and discovery respectively, Golgi and Ramón y Cajal shared the 1906 Nobel Prize in Physiology or Medicine. Golgi could not tell for certain that neurons were not connected, and in his acceptance speech he defended the reticular theory. Ramón y Cajal, in his speech, contradicted that of Golgi and defended the now accepted neuron doctrine. A paper written in 1891 by Wilhelm von Waldeyer, a supporter of Ramón y Cajal who coined the term neuron, debunked the reticular theory and outlined the Neuron Doctrine.

Ramón y Cajal also proposed that the way axons grow is via a growth cone at their ends. He understood that neural cells could sense chemical signals that indicated a direction for growth, a process called chemotaxis.

The relation between art and science in Ramón y Cajal's work

Ramón y Cajal's lifelong interest in painting and photography influenced his approach to scientific investigation. It was only when he began dissecting cadavers with his father (a physician and medical lab assistant), and learning about anatomy became a visual experience, that Ramón y Cajal grew interested in science. In Advice for a Young Investigator (1897), Ramón y Cajal cites French naturalist and zoologist Georges Cuvier, who claimed that people needed to understand their own artistic conventions and ways of representing the world before they could start comparing the forms of animals (Otis 2001).

The gallery of images below represents a sampling of Ramón y Cajal's scientific illustrations, which continue to be used in neuroscience textbooks:

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  Drawing of the neural circuitry of the rodent hippocampus in Histologie du Systeme Nerveux de l'Homme et des Vertebretes (Paris, 1911).

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  Drawing of the cells of the chick cerebellum, from Estructura de los centros nerviosos de las aves (Madrid, 1905).

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  Drawing of a section through the optic tectum of a sparrow, from Estructura de los centros nerviosos de las aves (Madrid, 1905).

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  From "Structure of the Mammalian Retina" (Madrid, 1900).

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  Drawing of Purkinje cells (A) and granule cells (B) from pigeon cerebellum (Madrid, 1899).

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  Drawing of Cajal-Retzius cells (1891).

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  Drawing of a Purkinje cell in the cerebellum cortex, clearly demonstrating the power of Golgi's staining method to reveal fine detail.

Ramón y Cajal as a writer: Vacation Stories

In 1905, Ramón y Cajal published Vacation Stories, five science-fictional tales, under the pseudonym Dr. Bacteria. Though written in 1885-86, the period immediately preceding his scientific breakthrough, Ramón y Cajal refrained from publishing them for nearly 20 years to publish them, perhaps fearing that their anti-establishment attitudes might jeopardize his scientific funding.

(more on the subject matter)

The stories were edited extensively in 1905, in part so that they could be associated w/ a Spanish literary movement called the Generation of 1898. A group of novelists, poets, essayists, and philosophers that included Azorín, Pío Baroja, and Miguel de Unamuno, the Generation of 1898 focused on the individual will as a mean’s to regenerate Spain, perceived of as on a slow cultural decline since the mid-17th century, and called for political and educational reform. A strong patriot, Ramón y Cajal wrote articles for liberal journals and identified as a socialist. His patriotism, however, extended to an imperialist attitude; he saw science as they key to recovering Spain’s lost empire, believing that bacteriologists would attack the microbes that prevented Europeans from settling in Africa (Otis 2001).

Vacation Stories was not only Ramón y Cajal's only foray into fiction: he had previously written two novels, both lost.

Biography

The son of Justo Ramón and Antonia Cajal, Ramón y Cajal was born of Aragonese parents in Petilla de Aragón, a poor, rural enclave in Aragon, in northeastern Spain. As a child he was transferred between many different schools due to his unruly behaviour and anti-authoritarian attitude. An extreme example of his precociousness and rebelliousness is his imprisonment at the age of eleven for destroying the town gate with a homemade cannon. He was an avid painter, artist, and gymnast, who preferred being out of doors rather than trapped in school memorizing lessons.

However, Justo Ramón, who himself had escaped poverty by becoming first a surgeon and later a physician, was determined to make his son a physician. Ramón y Cajal attended the medical school of Zaragoza, from which he graduated in 1873. A mandatory draft made him a military doctor, with the rank of caption, in the Spanish Army; he was sent him to first the Carlist campaign and later to Cuba (where uprising of Cuban nationalists demanding independence from Spain) served as a medical officer in the Spanish Army, where he contracted malaria. After returning to Spain, he married Silveria Fañanás García, with whom he had seven children (two of whom died in childhood).

Ramón y Cajal secured a post as an assistant professor at Zaragoza teaching anatomy in 1879, and was appointed as a university professor at Valencia in 1881. In 1883, he was made chair of the anatomy department there. He later held professorships in both Barcelona and Madrid, remaining in the latter position for 30 years. He was Director of the Zaragoza Museum (1879), Director of the National Institute of Hygiene (1899), and founder of the Laboratorio de Investigaciones Biológicas (1922) (later renamed to the Instituto Cajal, or Cajal Institute). Ramón y Cajal died in Madrid in 1934.

Selected works

Ramón y Cajal published over 200 scientific texts and articles, many of which were translated into French and German. Among his most notable publications are works of memoir and fiction.

• 1894-1904: Histology of the Nervous System of Man and Vertebrates 2 vols. (Textura del Sistema Nervioso del Hombre y los Vertebrados)
• 1897: Advice for a Young Investigator (Reglas y consejos sobre le investigación cientifica)
• 1905: Vacation Stories (Cuentos de vacaciones)
• 1913-1914: Degeneration and regeneration of the nervous system 2 vols. (Estudios sobre la degeneración y regeneración del sistema nervioso)
• 1917: Recollections of My Life (Recuerdos de mi vida)
• 1918: Manual of general pathological anatomy (Manual técnico de anatomía patológica)
• 1921: Cafe Conversations (Charlas de Café)
• 1934: The World From an Eighty-Year-Old's Point of View (El mundo visto a los ochenta años)

References

ISBN links support NWE through referral fees

• DeFelipe, J. 1998. MIT Encyclopedia of the Cognitive Sciences, Cambridge, MA: MIT Press.
• Everdell, W.R. 1998. The First Moderns. Chicago: University of Chicago Press. ISBN 0-226-22480-5.
• Kandel E.R., Schwartz, J.H., and T.M. Jessell. 2000. Principles of Neural Science, 4th ed. New York: McGraw-Hill.
• Ramón y Cajal, S. 1999 (1897). Advice for a Young Investigator. Trans. N. Swanson and L.W. Swanson. Cambridge: MIT Press. ISBN 0-262-68150-1.
• Ramón y Cajal, S. 1937. Recuerdos de mi Vida. Cambridge: MIT Press. ISBN 8-420-62290-7.
• Ramón y Cajal, S. 2001 (1905). Vacation Stories: Five Science Fiction Tales. Trans. L. Otis. Urbana and Chicago: University of Illinois Press. ISBN 0-252-07355-X.

External links

• The Nobel Prize in Physiology or Medicine 1906
• Life and discoveries of Cajal
• Ramon y Cajal, an Aragonese Nobel Prize

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