Cortical connectivity is embedded in resting state at columnar resolution

Nicholas S. Card, Omar Gharbawie

Abstract:

Resting state (RS) fMRI is now widely used for gaining insight into the organization of brain
networks. Functional connectivity (FC) inferred from RS-fMRI is typically at macroscale, which
is too coarse for much of the detail in cortical architecture. Here, we examined whether imaging
RS at higher contrast and resolution could reveal cortical connectivity with columnar granularity.
In longitudinal experiments (~1.5 years) in squirrel monkeys, we partitioned sensorimotor cortex
using dense microelectrode mapping and then recorded RS with intrinsic signal optical imaging
(RS-ISOI, 20 μm/pixel). FC maps were benchmarked against microstimulation-evoked activation
and traced anatomical connections. These direct comparisons showed high correspondence in
connectivity patterns across methods. The fidelity of FC maps to cortical connections indicates
that granular details of network organization are embedded in RS. Thus, for recording RS, the
field-of-view and effective resolution achieved with ISOI fills a wide gap between fMRI and
invasive approaches (2-photon imaging, electrophysiology). RS-ISOI opens exciting opportunities
for high resolution mapping of cortical networks in living animals.