  As the field of connectomics has matured, it has expanded from mapping the
existence of connections between brain components to measuring the strength of
connections. This information is increasingly accessible via methodologies such
as pairing functional magnetic resonance (MR) imaging and MR tractography in
the same human subject, as well as novel methods in non-human animals using
optogenetics. Systems and network neuroscience have in recent years focused
extensively on explaining correlation patterns of functional activity in the
brain in terms of the degree of connectedness of brain components, the
so-called functional connectivity-structural connectivity relationship (SC-FC).
What has been surprising has been how low the SC-FC correlations are. Why is it
that brain parts that are more well-connected appear not to engender more
correlated activity between them? Several explanations have been proposed but
one possibility has not been considered: perhaps more neural activity doesn't
imply more functional involvement. This article examines this possibility and
proposes a new general framework for understanding brain network dynamics based
on the design constraints of large-scale network communication systems. With
this new perspective, we may start to answer the article's main question, and
perhaps others.
