[robwwilliams]

I second the question below. The phase, magnitude, and polarity are all used. Yes, sure, you can focus on sub-systems with positive correlation under the presumption that joint increases in signal signify joint increases in O2 use and neuronal activity. Functional connectivity is functional more relevant than mere axonal connectivity. Only a small fraction of an axonal arbor — its collection of presynaptic terminals—-is functionally and reliably coupled to postsynaptic targets.