I assume that human brains can be considered as directed graphs with neurons as nodes and synapses as edges. I explicitly **don't** want to consider the *weights*, the *dynamics* of neural activity (based on the weights), and the adjustment of weights (*learning*) - just brains as static unweighted finite directed graphs.

Sensor neurons may be those having in-degree 0, actor neurons may be those having out-degree 0. (0 meaning "*essentially* 0".)

Considering human brains as finite directed graphs, for each question concerning finite directed graphs there should be an answer with respect to human brains.

Such questions might be:

How long is the

*shortest*path from a sensor to an actor neuron?How long is the

*longest*(direct) path from a sensor to an actor neuron?What is the (global/local)

*layer*structure (on different levels of granularity)?What is the (global/local)

*cycle*structure (on different levels of granularity)?

I find it hard to get answers to such questions considering human brains as directed graphs, because neuro-scientists don't think in terms of graphs, but for example in terms of signal paths and neuro-anatomy. But then - for them - "anything goes", and "everything is connected to everything" - which is not very helpful.

I would be very glad for any reference treating (formally) human brains as directed graphs.

reallywant to know what is the longest path from any sensory to an actor neuron. And Ireallyjust want to learn more about the layer and cycle structure(s) of the human brain. $\endgroup$ – Hans-Peter Stricker Nov 29 '16 at 1:05directed brain graphs. They say little work has been done specifically ondirectedbrain graphs, but that this "will be a priority for future technical innovation." Bullmore, Edward T., and Danielle S. Bassett. "Brain graphs: graphical models of the human brain connectome."Annual Review of Clinical Psychology7 (2011): 113-140. $\endgroup$ – Joseph O'Rourke Nov 29 '16 at 1:592more comments