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The nervous system is distinctive as compared to other tissue systems in human body owing to intricate structural organization. Histological studies played a key role in unveiling complex details of nervous tissue. However, the process of developing suitable staining method for nerve cells was arduous and spanned across almost half a century. The present study explored details of the journey involving quest for propitious staining method in neuroanatomy culminating in promulgation of neuron doctrine at the onset of 20th century. Initial efforts involving hematoxylin (including its diverse modifications) and subsequent adoption of analogous dye-based stains (like Nissl's method) had limited success in visualization of different parts of a nerve cell and structural details of nervous tissue. This was due to inability of dye-based stains to penetrate the connective tissue sheath of nervous tissue. Eventually, advent of metallic stains in form of silver impregnation method (Golgi stain), reduced silver impregnation method with gold stain (Cajal's stain) and silver carbonate staining method of Río-Hortega unraveled the structure of nervous tissue. The evolution of staining methods catalyzed the refinement of theories pertinent to constitution of nervous tissue. Golgi's staining led to emergence of reticular theory (neurons exist as a network) and Nissl's staining was the basis of the concept of Nervösen Grau (nerve cells and glial cells are embedded in mass of gray matter). Finally, Cajal's staining method successfully elucidated the complex anatomy of nerve terminals and resulted in emanation of neuron doctrine (neurons exists as individual units with adjacent connections)., (© 2024 American Association for Anatomy.)

Scientific reductionism, the view that higher level functions can be explained by properties at some lower-level or levels, has been an assumption of nervous system analyses since the acceptance of the neuron doctrine in the late 19th century, and became a dominant experimental approach with the development of intracellular recording techniques in the mid-20th century. Subsequent refinements of electrophysiological approaches and the continual development of molecular and genetic techniques have promoted a focus on molecular and cellular mechanisms in experimental analyses and explanations of sensory, motor, and cognitive functions. Reductionist assumptions have also influenced our views of the etiology and treatment of psychopathologies, and have more recently led to claims that we can, or even should, pharmacologically enhance the normal brain. Reductionism remains an area of active debate in the philosophy of science. In neuroscience and psychology, the debate typically focuses on the mind-brain question and the mechanisms of cognition, and how or if they can be explained in neurobiological terms. However, these debates are affected by the complexity of the phenomena being considered and the difficulty of obtaining the necessary neurobiological detail. We can instead ask whether features identified in neurobiological analyses of simpler aspects in simpler nervous systems support current molecular and cellular approaches to explaining systems or behaviors. While my view is that they do not, this does not invite the opposing view prevalent in dichotomous thinking that molecular and cellular detail is irrelevant and we should focus on computations or representations. We instead need to consider how to address the long-standing dilemma of how a nervous system that ostensibly functions through discrete cell to cell communication can generate population effects across multiple spatial and temporal scales to generate behavior., Competing Interests: The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Parker.)

Camillo Golgi was an extraordinary scientist whose contributions in the domain of neuroanatomy proved to be critical for emergence of neuroscience as a sovereign scientific discipline. Golgi's invention of the Black Reaction ( La reazione nera ) was a watershed event as it allowed remarkable visualization of the organizational pattern of elements of nervous system among complex puzzle of close knit interconnections. Till this time thin filamentary extensions of neural cells (axon and dendrites) could not be visualized with available staining techniques because of their slender and transparent nature. However invention of Black Reaction and its subsequent application demystified the basic architecture of brain tissue which was now visible to the scholars in all its complexity in microscopic studies. Golgi is also credited with the discovery of two types of sensory receptors in muscle tendons: Golgi tendon organ and Golgi-Mazzoni corpuscles. Golgi was the first to be successful in staining myelin component of axon, which he used to discover the myelin annular apparatus. He identified the complete life cycle of Plasmodium (malarial parasite) in human erythrocytes. His research on histological details of human kidney highlighted the existence of juxtaglomerular apparatus. Later on Spanish scientist Santiago Ramón y Cajal, based on the use of Golgi's Staining (Black Reaction) documented the morphologic details of nervous system in a more refined manner, which eventually led to the emergence of Neuron Doctrine . In recognition of their exemplary contributions in neuroscience Golgi and Cajal were jointly awarded the Nobel Prize for Physiology or Medicine in 1906.

Sherrington was a major proponent of the neuron doctrine and he was inspired by Santiago Ramón y Cajal's theory of dynamic polarization of nerve cells (Ley de la polarización dinámica de la célula nerviosa). Sherrington coined the term "synapse" to name the Cajal description of interneuronal contact and he gave the term, for functional nerve endings, as "Boutons terminaux," still used today. These two giants of neuroscience met only once, but they had a life-long friendship. It was Sherrington who wrote Cajal's Obituary for the Royal Society. We review here some of the scientific exchanges between Cajal and Sherrington, with particular attention to 1894, when the two neuroscientist met in London during Cajal's visit to deliver the Croonian Lecture to the Royal Society. We shall examine not only the scientific exchanges but also their friendship, which was immediate and strong. Anat Rec, 303:1181-1188, 2020. © 2019 American Association for Anatomy., (© 2019 American Association for Anatomy.)

Over the years the field of neuroanatomy has evolved considerably but unraveling the extraordinary structural and functional complexity of the brain seems to be an unattainable goal, partly due to the fact that it is only possible to obtain an imprecise connection matrix of the brain. The reasons why reaching such a goal appears almost impossible to date is discussed here, together with suggestions of how we could overcome this anatomical problem by establishing new methodologies to study the brain and by promoting interdisciplinary collaboration. Generating a realistic computational model seems to be the solution rather than attempting to fully reconstruct the whole brain or a particular brain region.

Dendritic spines are key components of a variety of microcircuits and they represent the majority of postsynaptic targets of glutamatergic axon terminals in the brain. The present article will focus on the discovery of dendritic spines, which was possible thanks to the application of the Golgi technique to the study of the nervous system, and will also explore the early interpretation of these elements. This discovery represents an interesting chapter in the history of neuroscience as it shows us that progress in the study of the structure of the nervous system is based not only on the emergence of new techniques but also on our ability to exploit the methods already available and correctly interpret their microscopic images.