[MD] Da Vinci's Brain

[Krimel]

MoQers All,

A while back dmb and I had a discussion about some anatomical drawings Da
Vinci made of the human brain. The point Dave made was that in Da Vinci's
early drawings he replicated anatomical errors that dated back to Galin.
Dave correctly used this as an example of how ones concepts govern ones
percepts. I believe Dave went on to make the point that all percepts are
governed by concepts which I disputed but that is another story. 

Those drawing illustrate a point I have tried to make in different contexts.
Imagine young Da Vinci presented with the opportunity to make such drawings.
He clearly was not ignorant of anatomy, He had studied it to some degree and
was familiar with the concepts. In his drawings he assimilated his
observations into that conceptual structure he had studies or was studying.
This is known as top down processing. This happens when conceptual
frameworks override perception. These conceptual frameworks were call schema
by Piaget and Da Vinci's early drawings are examples of what Piaget called
assimilation. Da Vinci made his observations fit into the existing schema.

Later in life Da Vinci did other anatomical drawing of the brain in which he
corrected his earlier errors and made original contributions to anatomical
observations. We could say that at this later time Da Vinci was familiar
enough with the schema and had accumulated more observations so that his
later drawings were guided more by his percepts. His observation drove the
content of his drawing. This is called bottom up processing and it happens
when perception overrides conception. In his later drawings Da Vinci changed
his schema to accommodate the new perceptual data. He made his schema fit
his observation.

Like Da Vinci we are capable of both top down and bottom up processing. Both
perception and conception are important but as James notes, in the end
concepts are derived from and subordinate to perception. We view Da Vinci's
early drawings as quaint and his later ones as ground breaking. It is true
that Da Vinci's later drawing were still governed by his conception of the
brain. But his drawings illustrate beautifully not only anatomy but the
dynamic interplay of static concepts and dynamic percepts.

Krimel