Day-1 : Basic Plan of the Nervous System
Warning- Julie Powell-esq Posts in the context of Neuroscience ahead!
The first lesson was primarily about the basic architecture of the nervous system, wherein it has been stated very powerfully that organisms, starting right from the phylum Cnidiria to the most complex organisms of the planet- Homo sapiens, have pretty much the same major nervous system parts but differ in terms of ontogeny and phylogeny.
While studying this chapter, a very important quote popped up in between by none other than René Descartes which, by far, is the most appropriate description of the brain and its property of consciousness-
“I think, therefore I am”
To understand the biological complexity of any organism, evolutionary and developmental studies are the two approaches by which it can be done. The brain roughly possesses 100 billion neurons and 100 trillion axonal connections. from the perspective of evolution, the organisms of the phylum Cnidirian were the first to develop neurons, the sensory neurons were the first ever neurons to evolve.
Furthermore, the development of the Neuron Doctrine occurred, which gave birth to two schools of thought regarding the architecture of the Nervous System- one was called as the Reticularist Theory which stated that neurons possess cytoplasmic continuity and when the axons enter the spinal cord, they fuse with other axons. This school of thought was backed up by scientists such as Camillo Golgi. Against this theory, proliferated the rather more accepted version, which happens to be the basis of the present doctrine.
It took into account the thoery of Schleiden and Schwann, i.e the cell theory of life, stated that the neurons like any other cell in the body are the fundamental units of the nervous system, which combine together to form a neural circuit to coordinate the processes of the body. This theory was backed up by Santiago Ramón y Cajal. Till this date, this has been the part of the Neuron Doctrine, which became the foundation for the modern neuroscience.
Charles Sherington provided the evidence of the existence of synapses which act as intercellular junctions, like that of desmosomes and adherence junction of Epithelia.
Neurons have probably evolved from ectoderm. Sensory neurons were the first one out of all the neurons to develop.
The “Bible” of structural neurosciences — The Histology of the Nervous System of the Man and the Vertebrates, written by Santiago Cajal, which contains the theory that sensory neurons have bipolar structure where one part detects the stimuli and the other transfers it to other neuron via cell body and dendrites, which is also termed as the functional polarity theory, was by far the most revolutionary discovery in the realm of Neuroscience.
All in all, I believe that the first day went in a pretty splendid manner and the journey that I have embarked upon will bring along quite a number of benefits for me.
I found a brilliant article while doing some research on Cajal, which gave a brilliant insight of how his diagrams of the neurons of the cerebral cortex has a sort of artistic touch, all drawn fby the help of a rudimentary microscope. Cajal received the Nobel Prize for Medicine in the 1906, and shared it with none other than Camillo Golgi.
To read more, click here:
https://blogs.scientificamerican.com/illusion-chasers/santiago-ramon-y-cajal-the-young-artist-who-grew-up-to-invent-neuroscience/
Until then, keep learning!
