Prelude to study of Deep Learning and Intelligent machines – Quick history of studies on Human Brain

 

Brain in Hieroglyphics

The study of human brain has a long history, spanning almost 5000 years from ancient Egypt through Greek civilization to modern times. Hieroglyphics scripts dating back to 1700 BC refer to the word brain The word “brain” appears on an ancient paper-like document (a “papyrus”) written around the year 1700 BC based on texts that go back to about 3000 BC. This text supposed to be written by the great Egyptian physician named Imhotep is the first book on surgery and also the first written record of the nervous system. This document is named Edwin Smith Surgical Papyrus. This ancient treatise was donated by Edwin Smith’s daughter in 1905 to New York Historical Society. 

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Mind and Soul in Brain

Alcmaeon (sixth-fifth century BC) of Crotone (a colony of ancient Greece), a pre-Socratic physician-philosopher, introduced the concept that mind and soul are located in the brain. Alcmaeon made observations about seeing, hearing, tasting, and smelling and distinguished perception from understanding. He is believed to be the first person to recognize the optic nerve.  

Figure-3: 

Alcmaeon of Crotone

 

Father of Scientific medicine

Hippocrates (460-379 BC) thought to be the father of scientific medicine stated that brain is involved with sensations and also the seat of intelligence. He thought that brain is the center of all pleasures, joys, laughter, jests as well as sorrows, pains, grief’s and tears. 

Figure-4: 

  Hippocrates refusing the presents of the Achaemenid Emperor Artaxerxes, who was asking for his services, painted by Girodet  

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Birth of Modern Science

The great philosophers Plato (428-347 BC) and his disciple Aristotle (384-322 BC) attempted to correlate the structure of human brain with its function. Plato was disciple of Socrates the classical Greek philosopher from Athens believed to be the founder of Western philosophy, and as being the first moral philosopher. Plato believed that brain is the seat of all mental processes. Plato’s disciple Aristotle wrote about “Sleep and Sleeplessness”. He believed that heart is the seat of sensation and ascribed to brain as a radiator having the task of cooling blood from the heart, and this cooling capacity provided the basis of rational behaviour in humans. 

According to Plato empirical evidence adulterated true knowledge. Although Aristotle was wrong in his assumptions of the brain, he had a different view about empirical evidence. It was he who questioned the value of speculative reasoning and invented the method of observation which laid the foundations of modern science. 

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Nerves are different from Blood Vessels and Tendons

Herophilus, also known as “The Father of Anatomy”, 335 - 225 BC and his student Erasistratus ( 304 - 250 BC) are believed to be first to differentiate nerves from blood vessels and tendons, and to realize that nerves convey neural impulses. Erasistratus complemented Herophilus’ teachings and research, and described the brain even more accurately, distinguishing the cerebrum from the cerebellum and sensory from motor nerves. The discoveries made by Herophilus and Erasistratus, thus, remained the pinnacle of anatomical knowledge for 1500 years. 

Figure-7:

Herophilus and Erasistratus

 

Soft and Hard matter

Rufus of Ephesus (AD 70 - 110) provided a physical description of the brain and showed that nerves proceeded from the brain. He identified the soft (pia mater) and hard (dura mater) layers encasing the brain.

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Brain separated into two parts

The Greek physician Galen (AD 130-210) in the Roman empire embraced the Hippocratic school of thought and observed that brain can be divided into two major parts (the cerebrum and the cerebellum). He associated cerebellum with sensations and cerebrum with controls. Galen considered that common sense, cognition, and memory were functions of the brain. Personality and emotion were not generated by the brain, but rather by the body as a whole (or perhaps by the heart and liver). Galen understood that spinal cord was an extension of the brain. 

Figure-9:

Galen treating the wounded Gladiators

Nerves are tissues

Medieval physicians  were in agreement with Galen. The Islamic medical philosopher Avicenna (AD 980 - 1037) wrote that “Nerves are one of the simplest members – homogeneous, indivisible, elementary tissues (others include the bone, cartilage, tendons, ligaments, arteries, viens, membranes and flesh)”. Ibn Sina, also known as Abu Ali Sina, Pur Sina, often known in the West as Avicenna, was a Persian polymath who is regarded as one of the most significant physicians, astronomers, thinkers and writers of the Islamic Golden Age,

Figure-10:

Spine treatment by Avicenna 

Da Vinci dissects Brain

The great Italian polymath Leonardo Da Vinci (AD 1452-1519) dissected the brain and made sketches of its different perspectives. He made accurate sketches of brain and cranial nerves, for the first time describing the olfactory nerves as cranial nerves and diagramming the crossing of nerves as optic chiasm. Leonardo also drew the vagus nerve.

 

Figure-11:

 In a drawing of a skull viewed obliquely from above, Leonardo shows the intracranial nerves and vessels. From the Royal Collection Trust / © Her Majesty Queen Elizabeth II 2019

Brain and Central Nervous System the sketch

The famous Dutch physician Andre Vesalius (AD 1514-1564) documented every scrap of human anatomy his eye could see. He made the first highly detailed map of the nervous system 

Figure-12: 

White and Grey matter

Archangelo Piccolomini or Arcangelo Piccolomini (AD 1525-1586) was an Italian anatomist and personal physician to a number of Popes. In 1586 he published the anatomical treatise Anatomicae praelectiones explicantes mirificam corporis humani fabricam, which he dedicated to Pope Sixtus V, who had just taken office, he was the first to describe and differentiate the white matter of the cerebrum from the grey matter.

 

Figure-13:

Pineal Gland

French mathematician Rene’ Descartes (AD 1596-1650) also contributed to the early understanding of human brain. He described pineal gland which is a tiny organ in the center of brain as the control and center of body and mind.

 

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Cartesian Dualism 

Birth of Neurology

Sixteenth and early seventeenth anatomists made significant progress in the understanding of brain. The English physician Thomas Willis AD (AD 1621-1675) published his book “Anatomy of Brain” and Dutchman Nicolaus Steno (AD 1638 - 1686) a pioneer in both anatomy and geology  published his “Lecture on the Anatomy of Brain” . Both of them severely criticized Galen for his ideas on animal spirits. Thomas Willis coined the term “neurologie” to  describe the study of neuroanatomy. 

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Steno made notable contributions in the fields of geology, anatomy, crystallography, and paleontology. He became a Catholic bishop, and died in self-imposed poverty. In 1988 he was beatified – the third of four steps needed to be declared a saint. 

Figure-16:

Blessed Nicolas Steno

 

Nerves fired by Electricity

In 1791, in the first suggestion that electrical impulses were important in the nervous system, Italian Luigi Galvani (AD 1737-1798) showed that electricity applied to nerves could make muscles contract. 

Figure-17:

Galvani and his frog experiment

Chemical and Other factors

In the late 18^th century physiologists began to connect the recent understanding on electricity and theories of the nervous system. Italian Giovanni Valentino Mattia Fabbroni (AD 1752 - 1822) suggested that nerve action involves both chemical and physical factors. 

Figure-18:

Chemical Transmission of nerve impulses

 

Regions discovered in Brain

In 1848, American railroad worker Phineas Gage had an iron rod strike his head, passing through his left frontal lobe. He survived, but aspects of his personality changed, suggesting that specific brain regions were important for certain functions. This idea grew stronger after studies in the 1860-70s by physician, surgeon, and anatomist Pierre Paul Broca (AD 1824-1880) and German neurologist Carl Wernicke (AD 1848-1905). They showed that specific parts of the brain were dedicated to different components of speech. 

Figure-19:

Language centers in brain

 

Speed of electrical impulses in nerves

In the 19th century, Hermann von Hemholtz,(AD 1821-1894) a German physician and physicist, measured the speed at which nerve cells produced electrical impulses. He was able to measure the speed of frog nerve impulses, and determined it to be about 27 meters/second.

The speed of nerve impulses varies enormously in different types of neuron, fastest nerve impulses can travel up to 288 km/h (180 mph).

 

 

Brodmann’s Areas

In more modern times Korbinian Brodmann (AD 1868 – 1918) the German neurologist defined the human cerebral cortex into 52 distinct regions.  The cerebral cortex is divided into 52 regions according to its cytoarchitectonic areas

 

 

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Recently neuroscientists have mapped each hemisphere of human ceberal cortex into 180 separate areas.

Neurons, units of the brain

In the early 1900s, anatomists were taking advantage of microscopes and new staining methods to explore the smallest parts of the brain. Spanish neuroscientist Santiago RamÓn y Cajal  (AD 1852-1934) and Itallian physician Camillo Golgi  (AD 1843-1926) were awarded the 1906 Nobel Prize for identifying that nerve cells (neurons) are the building blocks of the brain, and for showing they are of many different types.

 Camillo Golgi, used silver chromate salt to see what neurons looked like.

 

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And it was Santiago Ramón y Cajal (1852-1934), the Spanish neuroscientist who introduced the idea of neurons as the structural constituent of the brain.  He used a method developed by Golgi to stain nerve tissues to visualize the morphology and structure of neuron and their connections. Findings of Cajal and his students led to the “neuron doctrine” which proposed neuron as the functional unit of the nervous system. Cajal is widely considered the founding father of modern neuroscience. 

               

Figure-22:

A Purkinje neuron from human cerebrum drawn by Cajal

 

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Communication in the brain

In 1932 Englishmen neurophysiologist Sir Charles Sherrington (AD 1857-1952) and electrophysiologist Edgar Adrian (AD 1889-1977) won the Nobel Prize for proposing the concept of synapses (junctions between neurons, pictured). This resulted in increased research interest in neurosciences.

  

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Alan Hodgkin, Andrew Huxley and Australian Sir John Eccles won the Nobel Prize in 1963 for showing how neurons communicate via electrical and chemical signalling.

 

 Figure-25:

Communication between Neurons through the Synpase

 

Rapid growth of research interest in neurosciences

Ever since these developments neuroscience research is rapidly growing. Assisted by great advances in various areas of technology, and scientific areas such as physics and genetics, scientists have made great leaps in understanding the brain, through detailed imaging and mapping of networks and deciphering chemical pathways.

Neuroscience and Artificial Intelligence

The field of AI  and ANNs was born during the 1950s when early researchers began to pursue top-down models for mimicking human intelligence. Recent advances in AI retrace the same approach followed by early researchers. Researches in artificial neural networks have proved useful for studying the brain. Artificial neural networks are only a very coarse and rough analogy of how the brain works. ANNs model synapses as numbers in a matrix. In the neurosciences synapses are complex pieces of biological machinery that use both chemical and electrical activity to send or terminate signals, and that interact with their neighbours in dynamic patterns.

If an ANN can produce a pattern of neural activity that resembles the pattern that is recorded from the brain, scientists can examine how the system generates its output and then make inferences about how the brain does the same thing. This approach can be applied to any cognitive task of interest to neuroscientists. As an example if an ANN can be trained to process images we can understand how that network functions, and then use it to understand how brain process biological data. Focusing on the principles and mathematics researchers in AI and Neurosciences can share their knowledge to help advance research into both fields. This will lead to achieving new levels of ability for computers and understanding of natural brains.

References

1. brainworldmagazine.com/a-very-brief-history-of-neuroscience/
2. faculty.washington.edu/chudler/hist.html - Milestones in NeuroScience Research
3. web.stanford.edu/class/history13/earlysciencelab/body/nervespages/nerves.html
4. Alcmaeon of Croton's Observations on Health, Brain, Mind, and Soul, October 2012, Journal of the history of the neurosciences 21(4):409-26, DOI: 10.1080/0964704X.2011.626265
5. www.bibalex.org/SCIplanet/en/Article/Details?id=10296
6. web.stanford.edu/class/history13/earlysciencelab/body/brainpages/brain.html
7. The Medical Writings of Rufus of Ephesus, Thesis submitted for degree of Ph.D at University College, University of London by Amal Mohamed Abdullah Abou-Aly, discovery.ucl.ac.uk/id/eprint/1317541/1/246073.pdf
8. Galen's ideas on neurological function, F R Freemon, J Hist Neuroscience, 1994 Oct; 3(4):263-71. doi: 10.1080/09647049409525619.,
9. Neurophysiology: The man who bared the brain, Alison Abbott, Published: 13 May 2015, Nature volume 521, page160(2015)
10. wikivisually.com/wiki/Archangelo_Piccolomini
11. www.amacad.org/publication/neuroscience-study-nervous-system-its-functions
12. Thomas Willis and the background to Cerebri Anatome, James P B O'Connor, MA MB, J R Soc Med. 2003 Mar; 96(3): 139–143., doi: 10.1258/jrsm.96.3.139
13. www.medicalnewstoday.com/articles/248680#history
14. accessphysiotherapy.mhmedical.com/data/Multimedia/grandRounds/neuropt/media/neuropt_print.html
15. www.qbi.uq.edu.au/brain/intelligent-machines/understanding-brain-brief-history
16. www.cerebromente.org.br/n06/historia/bioelectr3_i.htm#:~:text=in%20the%20nerve%2Dmuscle%20plaque.&text=In%201852%2C%20Hermann%20von%20Helmholtz,be%20about%2027%20meters%2Fsecond.
17. www.brainpickings.org/2017/02/23/beautiful-brain-santiago-ramon-y-cajal/

18. 1.    www.cns.nyu.edu/~david/courses/perception/lecturenotes/brain/brain.html

Image Credits

Figure-1: image.slidesharecdn.com

Figure-2: image2.slideserve.com

Figure-3: tandfonline.com

Figure-4: wikipedia.org

Figure-5: pinterest.co.uk

Figure-6: twitter.com

Figure-7: bibalex.org

Figure-8: tibbiyelisozluk.com

Figure-9: alamy.com

Figure-10: sciencephoto.com/

Figure-11: dana.org

Figure-12: nlm.nih.gov

Figure-13: www.nlm.nih.gov

Figure-14: ocf.berkeley.edu

Figure-15: medicalnewstoday.com

Figure-16: famousscientists.org

Figure-17: vintagenewsdaily.com

Figure-18: hyperphysics.phy-astr.gsu.edu

Figure-19: psychology.wikia.org

Figure-20: accessphysiotherapy.mhmedical.com

Figure-21: slideplayer.com

Figure-22: brainpickings.org

Figure-23: center of neuroscience.nyu.edu

Figure-24: slideplayer.com

Figure-25: sites.duke.edu