Scaled Brain (Nervous System) Recognition in Early Greeks’ Time
Like the Egyptians and Babylonians, whose medical tradition was based on a combination of traditional magical and religious methods, some philosophers in Greece sought to develop a detailed anatomical understanding of the body. The era of the Greeks was critical in the appearance of future theories which reflected on the origins of neuroscience and neurology.
The rationale for some doctors therefore became the extensive documentation and theorization about the different parts of the body: their function, purpose, and inner workings. Physician-philosophers such as Alcmaeon, and, in later centuries physicians, Praxagoras and Herophilus, attempted to understand the biological form and function of the brain, and its relationship to the rest of the body. Being a physician within this atmosphere of philosophical inquiries, questions about the nature of the mind arose many theories which enrich the neuroscience.
Those are some of the most popular thinkers who enrich the science:
- and his theory of the brain:
Alcmaeon has been described as one of the most eminent natural philosophers and medical theorists of antiquity who lived in city of Crotone in Magna Graecia (now southern Italy) during the 5th Century BC. He has been referred to as “a thinker of considerable originality and one of the greatest philosophers, naturalists, and neuroscientists of all time. His work in biology has been described as remarkable, and his originality made him likely a pioneer.
Even Alcmaeon’s work was philosophical in nature; it aimed, not merely to observe, but also to understand the nature of things. The main theories of Alcmaeon relating to the brain are provided in summary below:
- Human beings can both perceive and understand:
Unlike animals, who can merely perceive, human beings have the capacity to interpret and place meaning on the objects they perceive. For Alcmaeon, thinking and perceiving are two different things. Human beings are capable of understanding because they can perceive and think about what they perceive [1].
- The brain is the center of the senses:
All the perceptions of which human beings are capable are connected to and transmitted from the brain. These sensations pass through passages which run to and from the brain. When the brain suffers some disaster, these passages are severely impeded, leading to the inability to move or feel. Because all the senses transfer what they perceive to the brain so that it can be decoded, the brain is essential for perception. He had recognized (sight, hearing, taste, and smell).
- Intelligence resides in the brain:
The brain is hegemonic in the body. The brain dictates not merely physical and mental function but also coordinates the relationship between the two. Mind and body are therefore not necessarily distinct, separate entities.
Alcmaeon’s investigations and theories were, however, provisional; so far as scholars are aware, his ideas were not conclusively proved or extended upon in his lifetime, Nonetheless, his work, even in its most basic form, laid the theoretical groundwork for further investigations into the nature of the brain.
- Praxagoras’s original hypotheses, 2nd important development in the history of neurology:
Praxagoras, a natural philosopher who born on the Greek island of Kos lived in the 4th Century, held this view. Praxagoras’ main contribution as a philosopher seems to have been the first to make a general, explicit distinction between arteries and veins and to explain their different functions. Alcmaeon had provided the beginnings of an answer to the question in the previous century, the theories had neither been properly tested nor thoroughly proved by examination of the body. Praxagoras had pustuled that there were in the body miniscule arteries that were responsible for transmitting signals through the body. Some arteries became so thin at their endings that their lumen (koilotès) virtually disappeared. For this final part he used the word “neuron” (νεῦραν), which was the Greek word for ‘cord’ or ‘sinew’. The nerves were no longer “poroi”. Praxagoras did not himself locate and identify neurons, however, After Alcmaeon’s original hypotheses, this was the second important development in the history of neurology.
- Herophilus reveals secrets after dissecting human cadavers:
Herophilus of Kos a student of Praxagoras, and so learnt about and discussed the theories of Alcmaeon and Praxagoras. He was born in Chalcedon, Asia Minor (now Turkey) in the late 4th Century BC, but did his important work in Alexandria, Egypt.
Herophilus was the first to examine and report on the structure of the nervous system. He was able to do this by dissecting human cadavers Figure 1, a practice that was in many places abandoned until the 16th Century [2]. This method allowed him to make many discoveries. Herophilus showed that the nervous system was distinct and separate from the cardiovascular system [3]. He noted the different function of sensory and motor nerves, something neither Alcmaeon nor Praxagoras hypothesized. In examining these nerves by dissection of the spinal regions, he was able to observe that they originate in the brain and are threaded throughout the whole body [4].
These discoveries were accompanied by the realisation that motor nerves were joined to muscles and sensory nerves to organs of sensation. In addition, Herophilus distinguished between the cerebrum and cerebellum and measured the pulse of blood through the body.
In making his observations, Herophilus was one of the first in history to acknowledge and correctly articulate the separate systems contained within the body and to prove the particular primacy of the brain as the prime mover of those systems.
Herophilus’ discoveries, and the theories of Alcmaeon and Praxagoras upon which they were built, can therefore be considered as the foundations of neuroscience and neurology.
References:
1 Panegyres, K.P., and Panegyres, P.K.: ‘The Ancient Greek discovery of the nervous system: Alcmaeon, Praxagoras and Herophilus’, Journal of Clinical Neuroscience, 2016, 29, pp. 21-24
2 Pearce, J.: ‘The neurology of Erasistratus’, J Neurol Disord, 2013, 1, (111), pp. 2
3 Von Staden, H., and Chalcedonius, H.: ‘Herophilus: the art of medicine in early Alexandria: edition, translation and essays’ (Cambridge University Press, 1989. 1989)
4 Longrigg, J.: ‘Greek rational medicine: philosophy and medicine from Alcmaeon to the Alexandrians’ (Routledge, 2013. 2013)
