Medieval Neuroscience, 400 – 1500 C.E.

Challenges to Galenic Theory

Medieval Europe had very little to contribute to the field, if any at all (Gross, 1987). There was an extreme preoccupation with the earthly body and heavenly spirit, and a heavy reliance on the theory of four humors. European contributions to neuroscience were made during the Renaissance.

The majority of neurological study in the Medieval world came from the Muslim world. During the Golden Age of Islam (700-1300 B.C.E.), there was a large growth in medical, technological, mathematical, legal, and artistic knowledge (Elbahnasawy, 2010). Many classical Greco-Roman texts were translated from their original languages into Arabic, and were later translated from Arabic to various other languages.

In the Golden Age of Islam, the validity of Galenic theory started being questioned by three notable scholars. While ibn Sina, ibn al-Nafis, and ibn al-Haytham began arguments against Galen’s anatomic theory, widespread skepticism did not begin until the 16th century in Europe.

ibn Sina (Avicenna)

 ibn Sina

Ibn Sina is one of the most famous Medieval Hellenistic Muslim philosophers, who wrote approximately 99 books throughout his lifetime on philosophy, religion, poetry, and memory (Islamic Philosophy Online, 2011).

Ibn Sina places logic and reasoning abilities in the category of mental functioning. He believed that sensation and perception are factors of memory. Conceptualizing theories requires the use of manipulating memories in order to understand the concept. With this idea, Ibn Sina almost equates imagination to intellectual ability.

ibn al-Nafis

File:Ibn al-Nafis.jpg

ibn al-Nafis

The discovery of pulmonary circulation is generally credited to Sir William Harvey in the 17th century, but was actually first discovered in the 13th century by ibn al-Nasif(Islamic Medical Student Association). His discovery disproved Galen’s explanation of blood circulation happening through “invisible pores.” ibn al-Nasif stated that blood must move from the right ventricle to the left, passing through the lungs.

He went on to overshadow ibn Sina by writing The Comprehensive Book of Medicine, an incomplete encyclopedia of medicine that eventually replaced Avicenna’s  “Cannon of Medicine.”

ibn al-Haytham (Alhazen)

File:Ibn al-Haytham.png

ibn al-Haytham

There is a common problem of being able to hit a pool ball at the right angle in billiards. This is sometimes referred to as Alhazen’s Billiard Problem (Weisstein, 2012). The video below shows the solution to the problem.

http://www.youtube.com/watch?v=3gLNUV8wgOE

Alhazen first discussed a similar concept in his work on optics. Much of his work consisted of the use of mirrors, the refraction of light, magnification, and optical lenses (Zahoor). He described vision as a single beam of light being reflected into the eye, with other ray is too small to be detected (Tschanz, 2012). This theory broke from Greek beliefs in rays of light leaving the eye itself to cause vision (O’Reagan).

Alhazen worked with the camera obscura, an invention which projects an inverted image through a pinhole. He applied the functional construction of the camera to the human eye, asserting that what humans see is reflected inside the brain upside down. This completely violated Galen’s optic theory of animal spirits traveling through the optic nerve.

File:Pinhole-camera.svg

Rudimentary structure of a pinhole camera        File:Gray722 refined.svgLithograph of the visual system from Grey’s Anatomy

 

By discrediting Galen’s anatomy, medical and scientific knowledge of the human body, and therefore the human brain, could begin advancing.

 

Resources

Elbahnasawy, R. (2010). Islamic Golden Age. Retrieved November 7, 2012, from http://www.elbahnasawy.com/author/index.php?option=com_content&view=article&id=48:islamic-golden-age&catid=2:culture&Itemid=6

Gross, C. G. (1987). Early History of Neuroscience. In Adelman, G. (ed.), Encyclopedia of Neuroscience, 843-847.

Islamic Medical Student Association (n.d.). The Contributions of the Islamic Empire to Medicine and Science. Wayne State University School of Medicine. Retrieved November 7, 2012, from http://www.med.wayne.edu/imsa/Islam%20and%20Medicine.html

Islamic Philosophy Online, (2011). Ibn Sina. Retrieved from http://www.muslimphilosophy.com/sina/art/ibn%20Sina-REP.htm#is4

O’Regan, J. K. (n.d.). Ancient Visions. Retrieved November 6, 2012, from http://nivea.psycho.univ-paris5.fr/FeelingSupplements/AncientVisions.htm

Rflodett (2011, June 21). Geometry and Billiards [Video File]. Retrieved from http://www.youtube.com/watch?v=3gLNUV8wgOE

Tschanz, D. W. (2012). Alhazen: Master of Optics – Science – Health & Science. OnIslam.net. Retrieved November 5, 2012, from http://www.onislam.net/english/health-and-science/science/412265.html

Weisstein, E. W. (2012). Alhazen’s Billiard Problem — from Wolfram MathWorld. Wolfram MathWorld: The Web’s Most Extensive Mathematics Resource. Retrieved November 6, 2012, from http://mathworld.wolfram.com/AlhazensBilliardProblem.html

Zahoor, A. (n.d.). Alhazen (965-1040 AD). UC Santa Barbara Geography. Retrieved November 5, 2012, from http://www.geog.ucsb.edu/~jeff/115a/history/alhazen.html

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