Reviewer B (Sebastian Seung)
I’d like to call for a more careful definition of the term “connectome.” For this we need a more precise definition of connection:
connection = projection + synapse
Tract-tracing using MRI or light microscopy is about *projections*, not connections. The same is true of light microscopy of single neurons labeled by the Golgi stain or other methods. Cajal inferred connections from projections, but those were just inferences. He could not truly find connections.
Kasthuri and Lichtman have proposed the term “projectome” to mean a complete map of axonal projections in the brain. I suggest that a new “projectome” entry be created in Scholarpedia. Most of the current article should be moved there.
The “connectome” article should be rewritten to truly focus on connections. Right now the only method for finding connectomes is 3d electron microscopy. Light microscopy with transsynaptic tracers is another method, but provides only partial information. The C. elegans connectome should be discussed more completely, as it is the only connectome that has been found so far.
Here's another way to think about it: The connectome follows the tradition of Brenner...though he hates the word :) The projectome follows the tradition of Cajal...who is not alive to complain about the word.
I could make a lot of other suggestions, but I think we need to resolve this basic issue before we go on.