Introduction

"Education is the kindling of a flame, not the filling of a vessel ", Socrates.

The nervous system (human in particular) is arguably the most complex and fascinating structure in the entire known universe to date. It is the foundation of our identity, our thoughts, our memory, our emotions, and all the sensations we experience at every moment. The nervous system allows us to see, hear, smell, and discover the world and environment to which we belong. It also allows us to act on this environment: it enables us to build, move, eat, adapt, and expand our faculties in order to apprehend both the most infinitely small particles and the immense and vast structures of the infinitely large universe.

All the rest of the body's organs are at the service of the nervous system: the digestive system supplies it with nutrients, the lungs provide it with oxygen, the cardiovascular system ensures the delivery of these resources, and the kidneys purify the blood of toxins that could damage it. Every organ in the body serves the nervous system in one way or another, because if this system fails, all of life goes with it.

Since the dawn of history, humanity has been looking for answers to several questions about thought, language, memory, and emotions. In the absence of resources, the answers were often misguided. Today, with science and technological development at its peak, we have some solid preliminary answers about how this incredible human machine works.

Unfortunately, the nervous system, as extraordinary and fabulous as it is, is not infallible. We sometimes see its functioning altered and its capacities decrease. As paradoxical as it may seem, it is largely thanks to these abnormalities that we have been able to discover how the nervous system works. Throughout the history of medicine, researchers and doctors have described neurological diseases and disorders in individuals; after their death, they examined the bodies to see what was missing, because the anatomical abnormalities of certain regions gave many clues about their roles in specific functions - functions such as language, memory, and emotions. However, these were impractical methods, as it was not until the individual died that the anomaly could be identified.

Comparative physiology with other animals has also always been a major contributor. But what has undoubtedly most marked modern science in this sense is the development of highly sophisticated methods and means of investigation: optical and electron microscopy, staining techniques, medical imaging (functional imaging in particular), the development of neurophysiology, etc.

All these means, and especially the dedicated people who took upon themselves to ask questions and worked hard to find answers to them, have allowed us to know a great deal about the nervous system today.

Understanding how the nervous system works and the mechanisms of its disorders provides insight into how research can be conducted, or at least in what direction, in order to find effective cures for horrific and devastating neurological diseases such as Parkinson's and Alzheimer's.