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This introductory chapter begins with a brief discussion of the many contributions of Santiago Ramón y Cajal, who is considered the father of modern neuroscience. He published almost 300 articles and several books of great importance, such as the classics Textura del Sistema Nervioso del Hombre y de los Vertebrados (1899-1904) and Estudios Sobre la Degeneración y Regeneración del Sistema Nervioso (1913-1914). He also received numerous awards and distinctions, including some of the most prestigious awards of his time: the Moscow Award (1900); the Helmholtz Gold Medal (1905); and the Nobel Prize for Physiology or Medicine (1906). The chapter then goes on to discuss why scientists often referred to trees and forests in their descriptions of the brain and, in particular, of the cerebral cortex, and how these neuronal forests served as an unlimited source of artistic and poetic inspiration to many scientists.

Many Mexican neuroscientists consider themselves to some extent to be descendants or at least beneficiaries of the School of Santiago Ramón y Cajal. This chapter outlines the genealogy linking them to this great Spanish master not only scientifically, but culturally, linguistically, and philosophically—beyond a strictly academic affiliation to one that is social and political in nature.

This chapter discusses the cellular and molecular mechanisms by which neurons are generated from the ventricular zone in the forebrain and migrate to their destinations in the cerebral cortex. Topics covered include radial migration, tangential migration, labelling techniques, and Cajal–Retzius cells. It is argued that the complexity added to the initial model of cortical development comes from the abundant populations recently discovered that use tangential migration. In turn, this reflects the intricate pattern of tangential movements during early telencephalic development. Although it was initially believed to be of little importance, this type of migration is fundamental during the earliest developmental stages.

This chapter discusses recent evidence on the genetic factors controlling Cajal–Retzius (C-R) cell production, differentiation, and migration during corticogenesis. Topics covered include genetic determinants of C-R cell differentiation, routes of C-R cell migration, and subtypes of C-R cells generated by distinct progenitor domains. It is shown that C-R cells are a heterogeneous population formed by distinct subtypes generated in different focal sites at pallial and subpallial locations that migrate toward the dorsal pallium following stereotyped routes. C-R cell subtypes differ not only in their place of origin and migratory routes but also in their gene expression profile.

This chapter first focuses on Alain Prochiantz, professor at the École Normale Supérieure, and his lab’s efforts to think about the adult human brain in embryogenetic terms. It then covers the emergence of (cellular) cerebral pathology from 1820s to 1870s; Ramón y Cajal’s large-scale study of the cellular emergence of the brain in its entirety beginning in the early 1890s; the emergence of new concepts of plasticity and pathology in the mid-1960s; studies on the relevance of adult neurogenesis for rethinking the diseases of the brain, specifically depression; and the rise of adult neurogenesis research, arguably the fastest growing branch of neuroscience between 2000 and 2010.

After an adventurous boyhood, Ramon y Cajal is persuaded by his father to study medicine. Inspired by the results of the Golgi staining method, he commences a thorough study of the structure of the nervous system, not only in man but in a variety of other species. Two of his conclusions are that the nerve cells are separate from each other, and that nerve impulses proceed from the dendrites to the axon. Frustrated with the limited recognition of his work, Cajal attends a meeting of anatomists in Germany and is finally accepted as a pioneer. Camillo Golgi, however, is skeptical of Cajal’s conclusions and makes this clear when they share the Nobel Prize in 1906.

The scientific career of Santiago Ramón y Cajal's consisted of three major phases. He was occupied with studies of a rather general histological character carried out with conventional techniques. From his studies the foundations of the neuron doctrine were firmly laid. He was jointly the Nobel Prize for Physiology or Medicine with Golgi. Cajal makes it clear in his autobiography that he entered the field of neural regeneration with some reluctance and largely because he felt that the neuron doctrine was under attack. He formulated the theory of chemotactism. For him, the principle of neurotropism was one of the fundamental laws of neurogenesis. He was unimpressed by the limited capacity displayed by the cerebellar cortex for regeneration. He also concluded that the regenerative phenomena observed are on the whole temporary reactions.

When maximally differentiated, the nervous system to a large extent loses its vegetative capacities, especially that of multiplication, acquiring instead an exquisite sensitivity to any pathogenic action culminating in degeneration and death. Cajal dedicates more than twenty of the most important works of his third period to the study of degeneration and regeneration in the peripheral and central nervous system. Trophic form as a degeneration necessarily falls on those constitutive elements of the nerves which form the central trophic action and cannot persist without the axon and the myelin. From the works of Cajal, the phenomena that occur in a nerve in degeneration are admirably represented. In this chapter degeneration and regeneration in the white matter, degeneration and regeneration in the gray matter, and neurotropism in nerve regeneration will be also explained one by one.

This chapter describes selected developments between the meeting of the German Anatomical Society in Berlin in 1889 and the publication twenty years later of Santiago Ramón y Cajal's treatise on the regeneration in the nervous system. Cajal formulated one of the early arguments for the Neuron Theory from studying the embryological development of nerve cells, particularly the sequential growth of their processes. In the two decades following Cajal's mission to Berlin, a flourishing research program was established, rooted in the neuron, the fundamental morphological and functional unit of the nervous system.

This chapter focuses on the cellular changes required to produce experience-dependent alterations in neural function. This account is grounded on issues raised by Santiago Ramón y Cajal. His treatise on neuroanatomy catalogued in 1909 a range of proposals for cellular mechanisms. Cajal envisaged a reinforcement of existing pathways through repetitive use as well as the creation of new pathways by a “continued branching and growth of dendritic and axonal arborizations.” In 1917 C. U. Ariëns Kappers in Amsterdam developed this notion of neuronal growth. Associative learning, he argued, resulted from the synchronous stimulation of neurons, with axons growing toward dendrites already active. Learning required the same processes that he imagined to be involved in neural development.

This chapter describes the development of a neuroscience project at Ross informed by literature and art. This project explores how a metaphor can serve as a trigger for interdisciplinary work in a school. Students started with Ramón y Cajal's scientific metaphor equating neurons to butterflies. This served as a launching pad for a series of scholarly investigations ranging from a linguistic analysis of the word butterfly in different contexts, to a review of scientific and other texts about butterflies, to time in the laboratory viewing neurons under the microscope. Students combined their skills about technology, art, neurobiology, and literature to create a digital video that converted the original metaphor into a living, visual form. This project illustrates the beauty of interdisciplinary learning, as well as the role of the spiral curriculum in transforming students' engagement in learning.

This chapter narrates the discovery of dendritic spines. It begins with Santiago Ramón y Cajal, a Spanish professor of Pathology and Histology, and his work entitled Estractura delos centros nerviosos de la aves (Structure of the Nervous Centers in Birds) and how he discovered the spines using the Golgi technique. Cajal defined “spine” on the spines of a rose bush, as it resembled one when he first investigated it in Purkinje cells.

The electrical aspect of the function of spines is explored in this chapter. Ramón y Cajal was the first one who proposed the idea of the electrical function of the spine, as he believed that the spine stores electric energy (Ramón y Cajal, 1904). This hypothesis was picked up 50 years later by Chang, who suggested that spines have electrical resistance, hence can attenuate synaptic inputs. It then explained that there are two categories of electrical property models of spines: the active and passive, according to whether they assume the presence of voltage-dependent conductances in spines. The chapter concludes by explaining that the electrical roles of spines has important repercussions for the function of the neuron, and it is likely that better knowledge of the electrical role of spines will change the general understanding of how neurons work.

This chapter discusses the author's research methodology to address the question: What venues for living a life, for being neurologically human, have the neuronal sciences opened up since 1891, when Wilhelm Waldeyer introduced the term neuron? He began by studying the genealogy of morals by turning to Santiago Ramón y Cajal, whose histology marked the emergence of the neurological human. What Ramón y Cajal then found when he set out to transform the development of the nervous system into a linear series of ink-pen drawings was that neurons must be thought of as instances of a free growth. From Ramón y Cajal, he then turned to German cytoarchitecture to study the cybernetic theories of the brain.

The nucleus is subdivided into a number of compartments that are not enclosed by membranes and whose main functions are transcriptional regulation and RNA processing. Many of the same proteins are found in different compartments, highlighting the dynamic exchange of components. The perinuclear compartment (PNC) is a hallmark of a number of different cancers. Cajal bodies (CBs) are sites of assembly of small nuclear ribonucleic particles (snRNPs) that function in messenger RNA (mRNA) or ribosomal RNA (rRNA) processing and in the biogenesis of telomerase. Nuclear speckles contain pre-mRNA splicing components and proteins involved in every aspect of gene regulation. Paraspeckles are involved in the processing and maturation of micro RNAs (miRNAs). Promyelocytic leukemia (PML) nuclear bodies contain the PML protein that has tumor suppressor activity by preventing the inactivation of p53. Under conditions of stress, the number and size of PML nuclear bodies increases. Transcription factories are nuclear regions where several RNA polymerase II (RNAPII) complexes are transcribing several genes. The co-localization of genes in transcription factories may lead to their co-regulation.