3D thought experiment to understand the construction of the brain.

Thought Experiment Three: Vat.

(Photo credit: Sinead Fenton)

I find trying to create a 3D image of the brain in my head a tad difficult.  The diagrams in books are still two-dimensional however skilled the artist.  Pictures of cross sections don’t seem to help me.  The mathematically talented can probably visualise it, but I need something more.

This works for me as a thought experiment:  blow up a balloon and partly fill it with pale pink jelly whipped with milk or cream.  The jelly should

A Twisted Family Tradition ~ The Lime Jello Brain

A Twisted Family Tradition ~ The Lime Jello Brain (Photo credit: hurleygurley)

English: A cranberry jello salad made in a rin...

English: A cranberry jello salad made in a ring mold. (Photo credit: Wikipedia)

be a little short on gelatine so it cannot hold much shape unsupported.  Take a large blob of chocolate on a stick.  How large?  It should be about 2/3 of the

Mousse au chocolat (sur fond transparent)

Mousse au chocolat (sur fond transparent) (Photo credit: Wikipedia)

volume of the jelly;  err on the side of being more.   Chocolate mousse would be better for authenticity but less practical.  Ideally the chocolate should be grey, but this grey chocolate is unattractive.

It’s our thought experiment, so chocolate mousse is fine.  Cut a few holes in the blob, then insert it into the balloon and finish filling the balloon with the pink jelly.  Some of the pink

English: Drawings of the cerebral cortex.

English: Drawings of the cerebral cortex. (Photo credit: Wikipedia)

jelly will fill the holes in the chocolate.

Now coat the balloon in chocolate.  Again, chocolate mouse would be closer to the right texture but impractical. Your choice.  Mould papier-mâché around the balloon and allow to set.

Human cerebral cortex, Brain MRI, Coronal slic...

Human cerebral cortex, Brain MRI, Coronal slices of a hemisphere with gray/white (yellow) and pial (red) surfaces overlaid. (Photo credit: Wikipedia)

Imagine that you can dissolve the balloon, just leaving the jelly, chocolate and papier-mâché.  The papier-mâché is the skull; the thin coating of chocolate is the cerebral cortex and made up of grey matter, neurons. Notice how the wrinkling in the picture below increases considerably the area of the cerebral cortex and therefore the volume as well.   The pale pink jelly is the white matter, largely made up of myelinated axons. The chunk of chocolate in

the middle is the cerebellum, cerebellar and cerebrum, mainly made up of grey matter, except where the jelly fills the holes.  The stick is the part of the spine that uses grey matter.  Of course, the dried papier-mâché is the skull.

brains!

brains! (Photo credit: cloois)

It all looks delicious, what a shame about  the papier-mâché skull.  You could try to carefully cut away the skull, pick up the brain and put it on the plate.  Oops, the brain collapses under its own weight.  I hope the plate was right beside the skull, ready to catch the brain.

Rainbow-Jello-Cut-2004-Jul-30

Rainbow-Jello-Cut-2004-Jul-30 (Photo credit: Wikipedia)

This thought experiment helped me understand why brains often bruise on the opposite side from where the head was struck.  I also realised how white matter can be effective as a transmitter of messages as it seems to be everywhere that the grey matter isn’t.

If you are interested in making a brain dessert, there are brain moulds around or use a ring-shaped jelly mould, fill in the hole with chocolate mousse and gently cover with almost set jelly.  Cover the whole thing with chocolate mousse and la voilà, an educational treat!

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