How Does the Brain Work Anyway A Look Back on the Study of Neuroscience

The brain continues to fascinate scientists and non-scientists alike because ittakes up so much real estate in our body and controls virtually everything we do fromtalking to breathing, thinking and moving. It is probably not surprising that reports about the nervous system (made up of our brain, spinal cord, and nerves spanning our whole body) date back to around 1700 B.C. with the ancient Egyptian document—the Edwin Smith surgical papyrus. The study of nervous system, or neuroscience, began when philosophers and medical practitioners began asking about the origin of emotions,intelligence, sensory perception, and diseases of the mind. Throughout its early history,neuroscience developed from being mostly theoretical to systematically testing ideasthat have laid the foundation for understanding how the brain works. The philosopher Alcmeaon of Croton shaped our current understanding of thebrain as early as 500 B.C. He suggested that contrary to what other philosophersbelieved, the brain, not the heart, was responsible for sensory perception andintelligence. Unlike few others at the time, Alcmeaon relied on empirical evidence, thatis what he could see for himself through observation of patients and anatomicaldissection, to drive his theories. This marked a transition from â€Å"divinely† inspired theoryto that based on evidence. As a result, the next few centuries were characterized byfindings based human cadaver and animal dissections where major structures of thebrain were identified, particularly in regard to the visual and motor system. In the 19 th century, a significant wave of discoveries paved the way for what isreferred to as â€Å"Modern Neuroscience, † where scientists began to unravel the buildingblocks of the brain—the neuron, and the extensive networks they form to processinformation and drive behavior. Santiago Ramon y Cajal is often hailed as the father ofmodern neuroscience because of the plethora of new ideas he introduced based ondetailed anatomical drawings of neurons. The rise of microscopy and improvements onthe methods scientists used to label neurons, paired with Ramon y Cajal’s artisticprowess, led to a slew of groundbreaking ideas. Among his greatest contributions wasthe idea that neurons were polarized individual units, not continuous in a network, butspaced by tiny gaps (now known as synapses). Ramon y Cajal’s beautiful drawingsinclude sketches of different cell types in the nervous system across many differenttypes of animals (humans, birds, flies) and in differen t states (diseased v. non-diseased). These drawings illustrated the similarity of nervous systems acrossorganisms and the rich diversity of cell types in the brain. The detailed description of the nervous system coincided with an increasingeffort to study the function of the brain. In 1842, Marie-Jean-Pierre Flourens introduceda systematic approach for lesioning parts of an animal brain in order to link it to aspecific function, a conceptual approach that is still widely used in Neuroscience.Additionally, seminal case studies such as that of Phineas Gage, provided importantinsight into the function of different parts of the brain. Upon having an iron rod pierce the frontal lobe of his brain, Gage became irresponsible and impulsive, which led scientists to propose that judgement and self-control were controlled by the frontal lobe of the brain. The work of Paul Broca and Carl Wernicke also supported the idea that parts of the brain have specific functions by finding that patients with speech impairments haddeficits in a regions of the brain now aptly called Broca and Wernicke’s area. Anotherinformative case study described â€Å"patient H M† who lost his short-term memory, as aresult of removing a part of the temporal lobe of his brain, the hippocampus, now knownto be vital for memory formation. Once scientists began to understand the organization and function of the brain,they began to ask how nerve cells were communicating with each other. Hodgkin andHuxley provided convincing evidence for the electrical properties of neurons thatallowed them to signal to each other rapidly. This stimulated the growth of a new fieldcalled electrophysiology, which is still studied today. Over the last hundreds years, neuroscientists have made important discoveriesabout how the brain controls just about everything we say and do. These discoverieshave set the framework for the current era of neuroscience (link to How does the brainwork anyway?: The field of Neuroscience today), which explores the molecules thatdrive development and function of the brain, and also takes a more focused approach todetermine how groups of neurons within specific brain regions work together togenerate behavior and how they go awry in disease. ;