Galen of Pergamon was a Greek physician and philosopher who was born in what is now modern-day Turkey. However, back then, it was known as the Roman Empire.

Today, Galen is best known for numerous anatomical discoveries and for treating patients across the empire, mainly in Rome. He was a well-known and respected individual known for treating Gladiators, which prompted him to form early theories about how the brain, spinal cord, and nerves controlled movement.

Ahead of his time, Galen believed the brain was the central organ for motion and was one of the first to describe and research reflexes or reflex-like movements. He dissected animals and observed how even after severing the brain, their limbs still twitched and moved, particularly when stimulated.

Though at the time, his theories were inaccurate and relied on the assumption that animal anatomy was similar to humans, his findings marked the beginning of research into involuntary motor responses and neural control of movement.

This research, many many centuries later, would contribute to the birth of athletic performance, reflex testing, and injury rehab.

(1): https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)62314-4/fulltext

(2): https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)61240-3/fulltext

(3): https://pdxscholar.library.pdx.edu/anthos/vol8/iss1/9/

(4): https://upload.wikimedia.org/wikipedia/commons/8/80/Galenus.jpg

Rene Descartes was a French philosopher and scientist who resided primarily in France and the then-Dutch Republic in the mid-1600s.

Descartes was one of the first scientists to propose a mechanical model of nervous system function. In this, he built on Galen's assumptions and introduced the idea of the reflex arc. He proposed that external sources or stimuli could produce involuntary responses. This idea was demonstrated by a person reflexively pulling their foot away from fire or something hot.

Essentially, he believed that nerves were tubes filled with "animal spirits" that traveled from the source of the stimuli to the brain, and then back, causing that involuntary movement or reflex. This concept, although anatomically incorrect, created the concept of the stimulus-response loop, which was revolutionary. His observations suggested that the body could react to environmental changes before the individual's mind could comprehend what was happening.

This idea would later be expanded upon by scientists and physiologists, expanding upon the reflex arc to include things such as motor control and reaction time.

(1): https://plato.stanford.edu/entries/descartes/

(2): https://www.cambridge.org/core/books/abs/cambridge-descartes-lexicon/animal-spirits/C857021D22C021EF7129A2D450740D98

(3): https://upload.wikimedia.org/wikipedia/commons/8/8a/Descartes-reflex.JPG

Luigi Galvani was an Italian physician and physiologist who is responsible for discovering that electrical signals can cause muscles to contract.

This finding was accomplished by him and his assistant hanging frog legs from an iron railing with brass hooks dangling from their spinal nerves. This would cause the leg to twitch even though the animal was already dead. Moreover, they found that placing the legs and hooks on other nonconductive materials did not result in a twitch. This finding built upon previous ideas of the nervous system and introduced the possibility that electricity played a role in function, rather than, say, animal spirits.

Due to the incorporation of electricity into the nervous system, his discovery laid the groundwork for the development of the concept "action potential" and bioelectricity, which is essentially how the brain communicates with muscles to create movement.

(1): https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/frogs/frogs-and-animal-electricity

(2): https://www.theiet.org/membership/library-and-archives/the-iet-archives/archives-highlights/galvanis-animal-electricity-experiments#:~:text=Galvani's%20Frog's%20Leg%20Experiment&text=Motu%20Musculari%2C%201792.-,A%20chance%20observation%20led%20Luigi%20Galvani%20(1737%2D98)%20to,connected%20to%20an%20electrical%20machine.

(3): https://www.historytoday.com/sites/default/files/2021-08/frogslegs.jpg

Robert Whytt was a Scottish physician and physiologist best known for some of the earliest experiments regarding reflexes. Building upon the previous discoveries, Whytt most notably published An Essay on the Vital and Other Involuntary Motions of Animals, which studied and explained how the spinal cord could generate movement without brain input (i.e., involuntary reflexes). This paper was published in 1751 in Edinburgh.

Continuing the usage of frogs in studying body mechanics and the nervous system, Whytt observed decapitated frogs and, like Galvani, who is discussed in the next entry, found that their legs moved when stimulated, even when dead. He described what is now known as the "stimulus-response" pattern and began the initial distinction of voluntary and involuntary motion and how it relates to the spinal cord.

Ultimately, this essay and the observations helped bridge the later findings of Galvani's electric experiments on frogs to be more applicable to bodily motion and spinal coordination.

(1): https://pmc.ncbi.nlm.nih.gov/articles/PMC1891630/

(2): https://m.media-amazon.com/images/I/41chxoOJuUL._AC_UF1000,1000_QL80_.jpg

The early 1800s played a crucial role in bridging the gap between experiments on frogs and theory, to translating that idea to muscle movement. Most notably, individuals such as Johannes Muller, Emil du Bois-Reymond, and Carl Ludwig all helped to transform the idea of reflexes and involuntary movement into a measurable process. They utilized electrical stimulation (like Whytt and Galvani) as well as mechanical recording tools to cement these findings.

Muller, for example, worked in a physiology lab in Germany, where he initially introduced the idea of the Law of Specific Nerve Energies, which essentially states that the nature of a sensation is determined by the specific nerve pathway stimulated, not the nature of the stimulus itself. For example, pressing or tapping, although different stimuli, result in the same neuro response as long as the sensation is applied to the same place.

Muller's student, Emil du Bois-Reymond, utilized this finding on striated muscle and discovered that electricity was associated with muscle contraction and nerve excitement (action potential).

Lastly, Carl Ludwig invented the kymograph in 1847, which was used to record muscular motion and changes in blood pressure, amongst other things. This discovery was incredibly important not just in the neuro field but beyond, as it began linking systems together, such as urine filtration and the cardiovascular system. Neuro-wise, because the kymograph could measure muscular motion, it helped to clarify the fact that the nervous system does communicate electrically and that motor control is a nerve-based process not a spiritual or purely mechanical-based one.

(1): https://www.britannica.com/biography/Carl-F-W-Ludwig

(2): https://www.britannica.com/science/specific-nerve-energy

(3): https://pmc.ncbi.nlm.nih.gov/articles/PMC9815794/#:~:text=He%20unveiled%20the%20fast%2Dchanging,by%20an%20externally%20applied%20current.

(4): https://c8.alamy.com/comp/RFT23R/carnegie-institution-of-washington-publication-30-metabolism-during-walking-measurement-of-the-step-lift-with-each-step-in-walking-the-body-is-raised-to-a-greater-or-less-degree-in-a-vertical-direction-and-this-becomes-an-appreciable-factor-in-the-amount-of-work-which-is-done-in-the-previous-research-in-this-laboratory-on-the-muscular-work-of-walking-a-dual-record-of-these-movements-was-obtained-by-means-of-a-work-adder-wheel-the-spring-pointer-introduced-by-professor-carl-tigerstedt1-and-a-kymograph-record-the-same-method-of-measurement-was-used-in-this-research-see-fig-7-exc-RFT23R.jpg

In 1870, German scientists Eduard Hitzig and Gustav Fritsch made groundbreaking neuromuscular discoveries by experimenting on dogs. They discovered that stimulating specific areas of the dog's brain cortex resulted in muscle movements. This was the first physical proof that the brain controlled not only involuntary movement (as seen with all the prior research on reflexes) but also voluntary muscle movement. It was also the beginning of motor cortex mapping (as seen through modern-day homunculus!)

The experiment in question was done in Berlin and, by using electrical currents, the scientists stimulated the dog's frontal lobe and observed which muscles were impacted (i.e if it was a limb, a facial muscle, etc.) This finding helped transition medicine fully to being brain-centric as it cemented the idea that the brain was truly the "control center" for the body as direct stimulation to it caused different body parts to react accordingly.

(1): https://neuroscientificallychallenged.com/posts/history-neuroscience-fritsch-hitzig-motor-cortex

(2): https://pubmed.ncbi.nlm.nih.gov/17620195/

(3): https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRltIKkMJv9Yv-h5UCwNyaH9r5MzqAY-eBKig&s

Although a Nobel prize-winning discovery, it is not the one in question. With that said, in 1906 Santiago Ramon y Cajal and Camillo Golgi won the Nobel Prize in Physiology or Medicine for the formation of the Neuron Doctrine.

For background, in Spain, Golgi developed a silver nitrate stain method that allowed for the visualization of neurons and their processes under a microscope. This process involved gardening nervous tissue and then soaking it in silver nitrate (hence the name), which would cause the black reaction staining the neurons, and thus, revealing their structures.

Cajal perfected this method, which enabled him the see the neuron in insane detail. Due to this, he argued that neurons were discrete units connected by gaps (synapses). He described the parts of the neuron, all the way from dendrites to axons, to the growth cones. This cemented the idea that neurons were the central signal receivers in the body and carried these signals towards the brain.

Moreover, this finding began to be used in the future to perfect the idea of neuron circuits and the reflex-response chain.

(1): https://www.nobelprize.org/prizes/medicine/1906/cajal/biographical/

(2): https://pubmed.ncbi.nlm.nih.gov/17315476/#:~:text=The%20Golgi%20silver%20impregnation%20technique,silver%20nitrate%20(black%20reaction).

(3): https://cdn.the-scientist.com/assets/articleNo/38476/iImg/19613/97966147-d9e8-435f-884b-80bb62103740-foundations.jpg

Throughout the early 1900s, in Oxford, much research was being done to expand upon the Neuron Doctrine and subsequent works.

Specifically, Sir Charles Scott Sherrington was an English neurophysiologist in charge of coining the term "synapse" and truly built upon the neuron doctrine to describe the gap between neurons. This gap is the place where communication - or synapses - occur. His work explained how sensory input becomes voluntary movement, specifically through the reflex arc which was discussed back in the first historical entry.

Sherrington introduced many essential questions about the nervous system and neurons, such as:

• How do neurons communicate?

• What pathway does a reflex stimulus follow?

Sherrington's discoveries ultimately led to the idea of inhibition and excitation in synapses, meaning that some signals get blocked to create movement. His work also proposed the idea that muscles are not simply innervated by nerves, but also send sensory information through this innervation (think sensory-loop). Additionally, his work led to a greater understanding of neural communication, reflexes, proprioception, spinal nerves, and muscle action.

It is important to note a deviation from Cajal's original beliefs as well. Cajal began to believe that the brain consisted of separate nerve cells, or neurons, however, Sherrington's observations helped form the idea that the brain actually functions as a continuous uninterrupted nerve that consists of multiple neurons communicating with each other.

(1): https://neuroscientificallychallenged.com/posts/history-of-neuroscience-charles-scott-sherrington

(2): https://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Charles_Scott_Sherrington2.jpg/640px-Charles_Scott_Sherrington2.jpg

In the 1920's British electrophysiologist Edgar Douglas Adrian developed a technique to record the electrical activity of individual neurons, building upon the discoveries and theories in the previous two historical entries. Ultimately, his work discovered that nerves communicate through rhythmic electrical impulses and that stronger stimuli increased signal frequency, not signal intensity.

Adrian conducted his research at the University of Cambridge in England. There, he utilized cathode-ray oscilloscopes that recorded the electrical activity in individual nerve fibers. His findings confirmed the following:

• Nerve impulses are, in fact, electric-based.

• The strength of a stimulus results in a change in firing length; however, the signal size in the neuron is the same. Higher stimuli result in higher firing.

• Neurons either fire or they don't. Building upon the previous finding, this meant that less strong stimuli don't result in a "half-fire" but rather just slower firing.

Adrian's findings, which would later lead to a Nobel Prize, changed how scientists ultimately began to view the brain and body. Transitioning towards the movement, or physiology-based fields such as sports medicine, Adrian's work can be directly attributed to findings on reaction time and reflex speed, and can be used to explain muscle fatigue and nerve injury.

(1): https://www.nobelprize.org/prizes/medicine/1932/adrian/biographical/

(2): http://trinitycollegechapel.com/about/memorials/brasses/adrian/

(3): https://www.pdn.cam.ac.uk/about-us/history/centenary/edgar-adrian

Nobel Prize in Physiology or Medicine 1932: Sir Charles Scott Sherrington and Edgar Douglas Adrian

In 1932, at the Nobel Assembly at the Karolinska Institute in Stockholm, Sweden, Sir Charles Scott Sherrington and Edgar Douglas Adrian were jointly awarded the Nobel Prize for their discoveries about the functions of individual neurons. Specifically, for their findings and differentiation of motor and sensory nerves. Their work, which took place from the late 1800s to the 1920s, explained how nerves transmitted signals, how reflexes operated, and how the brain and spinal cord interact to create sensory input and motor output.

To restate the previous entries, Sherrington introduced the idea of synapses in neurons, reciprocal innervation, and the reflex circle. Adrian worked on and proved how information is encoded and transmitted in neurons through electrical impulses.

When combined, their work ultimately revealed how everything combines to create simple and complex reflexes and voluntary movement.

(1): https://www.nobelprize.org/prizes/medicine/1932/ceremony-speech/

(2): https://pubmed.ncbi.nlm.nih.gov/16997762/

(3): https://www.tandfonline.com/cms/asset/29d742bf-7100-413d-b1f8-354a2c48870f/njhn_a_163877_o_f0001g.jpg

My contemporary entry will be the modern-day usage of surface electromyography (sEMG) and ultimately, how its usage in modern sports medicine uses the findings discovered above.

sEMG's are a piece of technology that records electrical signals from muscles in real-time. This technology is widely used in the sports medicine and rehabilitation fields to analyze muscle activation, fatigue, and motor control, while it is happening, allowing physicians and physios to give real-time feedback.

sEMG's are used around the world, mainly in rehab clinics and in professional athletic performance centers. They began to be used in the 2010s and have grown in popularity since.

This technology is truly a modern-day version of Adrian's original nerve findings and Sherrington's reflex theories. Due to sEMG's meaning, electrical signals in the muscle, physios can evaluate how well an individual's nerve to muscle communication is, allowing them to analyze and detect imbalances or delays in coordination ad reaction time.

Due to this, it enables individuals to create custom rehab programs tailored specifically to the patient's muscle sequencing, movement pattern, and reaction time.

(1): https://pmc.ncbi.nlm.nih.gov/articles/PMC7677519/

(2): https://tensegrityphysicaltherapy.com/semg-what-is-it/

(3): https://pmc.ncbi.nlm.nih.gov/articles/PMC4934580/

(4): https://i.ytimg.com/vi/eRxU4Pa39ME/maxresdefault.jpg

He was born on November 27, 1857, in London, where he was originally educated in the classics and philosophy. He was drawn to the arts, as his mother married a well-known archaeologist and artist. However, Sherrington was always drawn to movement and medicine and began training at RCSI and later in Berlin. What prompted much of Sherrington's work can all be boiled down to one event: the 1881 Medical Congress in London.

At this event, Sherrington listened to Sir Charles Bell discuss the effects of excisions of parts of the cortex of the brains of dogs and monkeys. Sherrington decided there and then that he wanted to further delve into these effects.

Much of Sherrington's earlier research took place between 1895 and 1898. As discussed above (specific dates and studies can be found in historical entries 8 and 10), it was focused on the nervous system and spinal cord injuries by analyzing animal reflexes. Through his research he was able to realize that the nervous system worked as a single unit rather than miniature systems all working together.

Ultimately, Sherrington’s ability to blend observation with animals and rigorous science made him one of the most important figures in neuroscience history, and why I chose him to be the docent/individual entry. His contributions are still cited in studies on reflex testing and neuromuscular coordination, all foundational in sports medicine.

(1): https://www.nobelprize.org/prizes/medicine/1932/sherrington/biographical/

(2): https://www.britannica.com/biography/Charles-Scott-Sherrington

(3): https://collectionimages.npg.org.uk/std/mw05776/Sir-Charles-Scott-Sherrington.jpg