History of neuroscience facts for kids

The story of how we learned about the brain is super old! From ancient Egyptians trying to preserve bodies to scientists in the 1700s studying tiny parts of the brain, people have always been curious. Early civilizations didn't have good tools to learn about the brain. So, their ideas about how our minds worked weren't always right. For a long time, people thought the brain was just "cranial stuffing." In ancient Egypt, when they prepared bodies for mummification, they often removed the brain. They believed the heart was where intelligence came from!

Ancient Times

A hieroglyph from the Edwin Smith Papyrus that means "brain" or "skull."

The very first time the brain is mentioned in writing is in the Edwin Smith Surgical Papyrus. This ancient Egyptian text was written around 1700 BC. The hieroglyph (an ancient Egyptian picture-word) for "brain" appears eight times in this papyrus. It describes the problems, diagnosis, and what might happen to two patients with bad head injuries and broken skulls. The person who wrote this (probably a battlefield surgeon) seemed to have a basic idea that head injuries affected people.

Even though the descriptions were detailed, they didn't have much medical knowledge to go on. The author noticed "the pulsations of the exposed brain" and said the brain's surface looked like rippling copper slag (which actually looks a bit like the brain's folds!). They also noticed that an injury on one side of the head caused problems on that same side. They even described problems with speaking ("he speaks not to thee") and seizures ("he shudders exceedingly") after head injuries. This shows that ancient people had some understanding of how the brain worked and how important it was to protect the head. It's amazing that these observations were based on simple looking and logical thinking, especially since most medical ideas back then were based on myths!

In Ancient Greece, people started to get really interested in the brain. A scientist named Alcmaeon seemed to have studied the eye and connected the brain to vision. He also suggested that the brain, not the heart, was the main organ that controlled the body. He thought our senses depended on the brain. Alcmaeon believed the brain was where memories and thoughts happened because it could put all our sensations together. The writer of a book called On the Sacred Disease, which was part of the Hippocratic writings, also thought the brain was the center of intelligence.

The debate about which organ controlled the body went on for a long time among Greek thinkers. In the 300s BC, Aristotle believed the heart was where intelligence came from. He thought the brain was just a cooling system for the blood! He even said humans were smarter than animals because we have a bigger brain to cool our "hot-bloodedness." But during the Hellenistic period, two scientists from Alexandria, Herophilus and Erasistratus, studied human bodies by dissecting them. They found strong evidence that the brain was the most important organ. They even figured out the difference between the cerebrum and the cerebellum, and found the brain's ventricles and the dura mater (a tough membrane around the brain). Sadly, most of their writings are lost, and we only know about their amazing discoveries from other sources. Some of their findings had to be rediscovered a thousand years later!

During the Roman Empire, a Greek doctor and philosopher named Galen dissected the brains of animals like oxen, monkeys, and pigs. He noticed that the cerebellum was denser than the cerebrum, so he thought it must control muscles. Since the cerebrum was softer, he believed it was where our senses were processed. Galen also thought that the brain worked by "animal spirits" moving through the ventricles. He also saw that specific nerves in the spine controlled specific muscles. His ideas about the spine weren't fully improved upon until the 1800s!

Medieval to Early Modern Times

During the Middle Ages, Islamic medicine focused on how the mind and body worked together. They really emphasized understanding mental health. Around the year 1000, Al-Zahrawi, who lived in Islamic Spain, treated patients with brain and nerve problems. He performed surgeries for head injuries, skull fractures, spinal injuries, and headaches. In Persia, Avicenna (also known as Ibn-Sina) had very detailed knowledge about skull fractures and how to treat them with surgery.

Some people call Avicenna the father of modern medicine. He wrote 40 books on medicine, and his most famous was the Qanun, a huge medical encyclopedia used in universities for almost a hundred years. He also explained things like insomnia, mania, hallucinations, nightmares, dementia, epilepsy, stroke, paralysis, vertigo, and tremors. He even described a condition similar to schizophrenia, which he called Junun Mufrit. This condition involved agitation, sleep problems, giving strange answers, and sometimes not being able to speak. Avicenna also discovered parts of the brain called the cerebellar vermis and the caudate nucleus. These names are still used today! He was also the first person to connect mental problems with issues in the brain's middle ventricle or frontal lobe. Other important doctors in the Medieval Muslim world, like Abulcasis, Averroes, Avenzoar, and Maimonides, also described many brain-related medical issues.

Between the 1200s and 1300s, the first anatomy textbooks in Europe were written by Mondino de Luzzi and Guido da Vigevano. These books included descriptions of the brain.

The Renaissance

One of Leonardo da Vinci's drawings of the human skull.

During the Renaissance, a scientist named Andreas Vesalius studied human bodies. He found some problems with Galen's old ideas about anatomy. Vesalius carefully noted many details about the brain and the whole nervous system during his dissections. He recorded features like the putamen and corpus callosum. Vesalius also suggested that the brain had seven pairs of "brain nerves," each with a special job. Other scholars continued Vesalius's work, adding their own detailed drawings of the human brain.

The Scientific Revolution

In the 1600s, René Descartes studied how the brain worked. He came up with the idea of dualism, trying to explain how the brain and mind are connected. He thought the pineal gland was where the mind and body interacted. This was after he studied how the brain makes and moves cerebrospinal fluid. Jan Swammerdam did a cool experiment with a frog's leg muscle. He put it in a syringe with water and made the nerve twitch. The water level didn't rise, it actually went down a tiny bit! This showed that nerves didn't just inflate muscles like balloons, which was a popular idea then. This experiment was important because it suggested that behavior comes from stimuli (things that make us react). Thomas Willis also studied the brain, nerves, and behavior to find ways to treat nerve problems. He described in great detail the structure of the brainstem, the cerebellum, the ventricles, and the large parts of the brain called the cerebral hemispheres.

Modern Times

The idea that electricity plays a role in nerves was first seen in dissected frogs by Luigi Galvani, Lucia Galeazzi Galvani and Giovanni Aldini in the late 1700s. In 1811, César Julien Jean Legallois was the first to figure out a specific job for a brain region. He studied breathing in animals and found that the center for breathing was in the medulla oblongata. Between 1811 and 1824, Charles Bell and François Magendie discovered something important by dissecting and studying living animals. They found that the front roots of the spinal cord send out signals for movement, and the back roots receive sensory information (this is called the Bell–Magendie law). In the 1820s, Jean Pierre Flourens started a new way of experimenting. He would remove small parts of animal brains and then watch how it affected their movement, senses, and behavior. He found that removing the cerebellum made movements "not regular and coordinated." In 1843, Carlo Matteucci and Emil du Bois-Reymond showed that nerve fibers actually send electrical signals. Hermann von Helmholtz even measured how fast these signals traveled in 1850 – about 24 to 38 meters per second!

In 1848, John Martyn Harlow wrote about Phineas Gage, a railroad worker whose frontal lobe was pierced by an iron rod in an accident. Phineas Gage became a famous case study showing the link between the prefrontal cortex (the front part of the brain) and our executive functions (like planning and decision-making). In 1861, Paul Broca heard about a patient who had slowly lost the ability to speak over 21 years, but could still understand things and think clearly. Broca performed an autopsy after the patient died and found a lesion (a damaged area) in the frontal lobe of the left side of his brain. Broca published his findings from 12 patients in 1865. His work encouraged other scientists to do careful autopsies to connect more brain areas to senses and movements. Another French neurologist, Marc Dax, had made similar observations earlier.

Broca's idea was supported by Gustav Fritsch and Eduard Hitzig. In 1870, they found that if they electrically stimulated the motor cortex of a dog, specific parts of its body would twitch. John Hughlings Jackson also supported this idea by watching epileptic patients in the 1870s. He correctly guessed how the motor cortex was organized by watching how seizures spread through the body. Carl Wernicke further developed the idea that specific brain parts specialize in understanding and producing language. Richard Caton showed in 1875 that the brains of rabbits and monkeys had electrical activity. In 1878, Hermann Munk found that vision was controlled in the back part of the brain (occipital cortex) in dogs and monkeys. David Ferrier found in 1881 that hearing was in the superior temporal gyrus. And in 1909, Harvey Cushing found that the sense of touch was in the postcentral gyrus. Even today, modern research still uses the brain maps from this time, like those by Korbinian Brodmann, to show that different areas of the brain are active for different tasks.

Studying the brain became much more advanced after the invention of the microscope. Also, a special staining method was developed by Camillo Golgi in the late 1890s. He used a silver salt to show the amazing, detailed structures of single neurons (brain cells). His technique was used by Santiago Ramón y Cajal, which led to the idea of the neuron doctrine. This idea says that the basic working unit of the brain is the neuron. Golgi and Ramón y Cajal even shared the Nobel Prize in Physiology or Medicine in 1906 for their detailed observations and descriptions of neurons throughout the brain. The neuron doctrine was further supported by experiments that built on Galvani's early work on how muscles and neurons use electricity. In 1898, British scientist John Newport Langley first used the term "autonomic" to describe the connections of nerve fibers to nerve cells outside the brain and spinal cord. Langley is known for his ideas about "chemical receptors" and "receptive substance." Towards the end of the 1800s, Francis Gotch did several experiments on how the nervous system works. In 1899, he described the "inexcitable" or "refractory phase" that happens between nerve impulses. He mainly focused on how nerves affected muscles and eyes.

In 1887, Heinrich Obersteiner started the "Institute for Anatomy and Physiology of the CNS" in Vienna, Austria. This was one of the first brain research centers in the world! He studied the cerebellum and wrote one of the first books on neuroanatomy in 1888. Róbert Bárány, who studied the ear's balance system, also went to this school.

The 1900s

In the 1900s, neuroscience really started to be seen as its own unique field of study. Before this, studying the nervous system was just a small part of many different sciences.

Ivan Pavlov made many contributions to how we understand nerves and the body. Most of his famous work was about conditioning (like Pavlov's dogs!) and involuntary reflex actions. In 1891, Pavlov was invited to lead the Physiology Department at the Institute of Experimental Medicine in St. Petersburg. He published his book The Work of the Digestive Glands in 1897 after 12 years of research. His experiments won him the 1904 Nobel Prize. Around the same time, Vladimir Bekhterev discovered 15 new reflexes. He also founded the Psychoneurological Institute in 1907, where he tried to combine many different ways of studying the brain.

Charles Scott Sherrington focused a lot on reflexes. His experiments led to the discovery of motor units (groups of muscle fibers and the nerve cell that controls them). His ideas centered on how cells work together, either being activated or stopped at what he called synapses (the tiny gaps between nerve cells). Sherrington won the Nobel Prize for showing that reflexes need different parts to work together. He also showed how muscles work in pairs (when one contracts, the other relaxes). Sherrington also worked with Thomas Graham Brown, who, in 1911, came up with one of the first ideas about central pattern generators. Brown realized that the basic pattern of stepping could be produced by the spinal cord itself, without needing commands from the brain.

Acetylcholine was the first neurotransmitter (a chemical messenger in the brain) ever found. It was first identified in 1915 by Henry Hallett Dale for how it affected heart tissue. It was confirmed as a neurotransmitter in 1921 by Otto Loewi in Austria. Loewi showed how nerves could release a chemical that affected the heart in frogs. He first called it Vagusstoff because it came from the vagus nerve.

This graph shows the "all-or-none" rule for how nerves respond.

A big question for brain scientists in the early 1900s was how nerve impulses worked. In 1902 and 1912, Julius Bernstein suggested that the electrical signal (action potential) in a nerve came from a change in how easily ions (charged particles) could pass through the nerve cell's outer layer. Bernstein was also the first to use a special equation to describe the resting electrical charge across the nerve cell membrane. In 1907, Louis Lapicque suggested that the action potential was created when a certain "threshold" was reached.

A lot of study on sensory organs and nerve cells was done by British scientists Keith Lucas and his student Edgar Adrian. Keith Lucas's experiments in the early 1900s proved that muscles either contract completely or not at all – this is called the all-or-none principle. Edgar Adrian watched nerve fibers in action during his experiments on frogs. This showed that scientists could study how the nervous system worked directly, not just indirectly. This led to a rapid increase in experiments and new technology for studying the brain. Much of Adrian's early research was inspired by how vacuum tubes intercepted and boosted coded messages. At the same time, Josepht Erlanger and Herbert Gasser were able to change an oscilloscope (a device that shows electrical signals) to work at low voltages. They saw that action potentials happened in two parts: a sharp spike followed by a smaller after-spike. They found that nerves came in many forms, each with its own ability to be excited. With this research, they discovered that the speed of action potentials was directly related to the diameter of the nerve fiber. They won a Nobel Prize for their work!

3-D models of the sensory and motor homunculi at the Natural History Museum in London. These show how much brain space is dedicated to different body parts.

While treating epilepsy, a doctor named Wilder Penfield created maps of where different functions (like movement, senses, memory, and vision) were located in the brain. He put his findings in a 1950 book called The Cerebral Cortex of Man. Wilder Penfield and his team are known for creating the idea of the cortical homunculus. This is a distorted drawing of the human body that shows how much brain space is used for different body parts.

Kenneth Cole made big steps in understanding the electrical properties of nerve tissue. Bernstein's idea about the action potential was confirmed by Cole and Howard Curtis, who showed that the membrane's ability to conduct electricity increases during an action potential. David E. Goldman worked with Cole and developed the Goldman equation in 1943, which helps explain the electrical charge across cell membranes.

Alan Lloyd Hodgkin and Andrew Huxley later created a mathematical model to explain how electrical signals are sent and started in the giant nerve fiber of a squid. This is known as the Hodgkin–Huxley model. In 1962, Bernard Katz created a model for how neurotransmission (nerve signals) happens across the tiny gaps between neurons called synapses. Starting in 1966, Eric Kandel and his team studied how learning and memory storage cause chemical changes in neurons, using a sea slug called Aplysia.

Eric Kandel and his team have said that David Rioch, Francis O. Schmitt, and Stephen Kuffler were very important in starting the field of neuroscience. Rioch combined basic brain research with mental health studies in the 1950s. Around the same time, Schmitt started a neuroscience research program at MIT, bringing together biology, chemistry, physics, and math. The first stand-alone neuroscience department was founded in 1964 at the University of California, Irvine by James L. McGaugh. Stephen Kuffler started the Department of Neurobiology at Harvard Medical School in 1966. The word "Neuroscience" itself might have first been used in 1962 with Francis O. Schmitt's "Neuroscience Research Program" at MIT.

Over time, brain research has gone through phases of philosophy, experiments, and theories. In the future, simulating the brain with computers is expected to be very important.

Institutes and Organizations

Because more and more people became interested in the nervous system, many important neuroscience institutes and organizations have been created. These groups provide a place for all brain scientists to share their work. The largest group for neuroscience professionals is the Society for Neuroscience (SFN). It's based in the United States but has many members from other countries.

In 2013, the BRAIN Initiative was announced in the US. An International Brain Initiative was created in 2017. It now includes more than seven national brain research projects from different countries (like the US, Europe, Allen Institute, Japan, China, Australia, Canada, Korea, and Israel).

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