Edge of the Brain

I have been using an icon consisting of interlocking ‘C’s in a number of my watercolor studies. My composition below is a visual explanation of that icon.

Watercolor Pen and Ink: Hem of the Border

9″x12″ 140# Cold Pressed Watercolor Block

The idea of the interlocking ‘C’s come from a electron micrograph of a cross section of the brain through the hippocampus.  I have expanded in much more detail in my post, My Favorite Part of the Brain, but one passage bears repeating:

“Imagine that we fold over the 3 layered part of this sheet all around the edge. Furthermore, imagine that before we do this, we put a string inside the pleat, like the string that always seems to get lost inside the pajama bottoms (or does that just happen to me?). When we pull the string, we get a puckered circle, like a lady’s purse, or like pursed lips. Broca, described it in exactly this way:

‘As it surrounds the threshold of the hemisphere the mantle forms a border which resembles the circular edge of a purse. Hence I am calling this border the limbus of the hemisphere and the convolution that forms it the ‘limbic convolution.’  (1)

The great neuroanatomist Walle Nauta concurs with Broca’s description:

Little wonder, all in all, that Broca decided he had found the edge of the cerebral cortex, at least in the temporal lobe, and little wonder that he initially chose to call his discovery the great lobe of the hem.’ (2)”

(1)  Broca, P. Anatomie compare des circonvolutions cerebrales. Le grand lobe limbique et la scissure limbique dans la serie des mamiferes, Rev. Anthrophol.1 Ser. 2. (1878). pp.385-455.  Quoted from A. Lautin, Limbic Brain  Kluwer Academic/Plenum Publishers (2001)

(2) Nauta, W.J.H and Fiertag, M. Fundamental Neuroanatomy.  W.H.Freeman and Company, NY. (1986) Quoted from A. Lautin, Limbic Brain  Kluwer Academic/Plenum Publishers (2001)

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