April 07, 2018 Saturday
Bedtime Story
Concluding Remarks of the Paper: ‘The Human Brain in Numbers: A Linearly Scaled-up Primate Brain’ - Part 1
Today finally we shall read through the
concluding remarks of the paper ‘The Human Brain in Numbers: A Linearly
Scaled-up Primate Brain’ published in the journal Frontiers in Human
neuroscience in 2009 (though I would prefer you read the entire paper on your
own).
“Concluding Remarks: Our Place in Nature
Novel quantitative data on the cellular
composition of the human brain and its comparison to other primate brains
strongly indicate that we need to rethink our notions about the place that the
human brain holds in nature and evolution, and rewrite some of the basic
concepts that are taught in textbooks.
Accumulating evidence (from the works of T.
W. Deacon ‘What makes the human brain different?’, Roth G. Dicke ‘Evolution of
the brain and intelligence’, and R.O. Deaner et al ‘Overall brain size, and not
encephalization quotient, best predicts cognitive ability across non-human
primates’) indicates that an alternative view of the source of variations in
cognitive abilities across species merits investigation: one that disregards
body and brain size and examines absolute number of neurons as a more relevant
parameter instead.
Now that these numbers can be determined in
various brain and their structures (by the innovative ‘brain soup’ method),
direct comparisons can be made across species and orders, with no assumptions
about body-brain size relationship required.
Complimentarily, however, it now becomes
possible to examine how numbers of neurons in the brain, rather than brain
size, relate to body mass and surface as well as metabolism, parameters that
have been considered relevant in comparative studies, in order o establish what
mechanisms underlie the loosely correlated scaling of body and brain.
According to this now possible
neuron-centered view (reminds me of Dawkins’ gene-centered view – Pan narrans),
rather than the body-centered view that dominates the literature, the human
brain has the number of neurons that is expected of a primate brain of its
size; a cerebral cortex that is exactly as large as expected for a primate
brain of 1.5 kg; just as many neurons as expected in the cerebral cortex for
the size of this structure; and, despite having a relatively large cerebral cortex
(which, however, a rodent brain of 1.5 kg would also be predicted to have),
this enlarged cortex holds just the same proportion of brain neurons in humans
as do other primate cortices (and rodent cortices, for that matter).
This final observation calls for a
reappraisal of the view of brain evolution that concentrates on the expansion
of cerebral cortex, and its replacement with a more integrated view of
coordinate evolution of cellular composition, neuroanatomical structure, and
function of cerebral cortex and cerebellum.
Other “facts’ that deserve updating are the
ubiquitous quote of 100 billion neurons (a value that lies outside of the
margin of variation found so far in human brains; and, more strikingly, the
widespread remark that there are 10x more glial cells than neurons in the human
brain.
As we have shown, glial cells in the human
brain are at most 50% of all brain cells, which is an important finding since
it is one more brain characteristic that we share with other primates (F. A.
Azevedo et al ‘Equal number of neuronal and nonneuronal cells make the human
brain an isometrically scaled-up primate brain’ Journal of Computational
Neurology 2009).”
Stay tuned to the voice of an average story storytelling
chimpanzee or login at http://panarrans.blogspot.com
Good night mon ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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