Decoding Task-Specific Cognitive States with Slow, Directed Functional Networks in the Human Brain.

Flexible functional interactions among brain regions mediate critical cognitive functions. Such interactions can be measured using functional magnetic resonance imaging (fMRI) data either with instantaneous (zero-lag) or lag-based (time-lagged) functional connectivity. Because the fMRI hemodynamic response is slow, and is sampled at a timescale (seconds) several orders of magnitude slower than the underlying neural dynamics (milliseconds), simulation studies have shown that lag-based fMRI functional connectivity, measured with approaches like Granger-Geweke causality (GC), provides spurious and unreliable estimates of underlying neural interactions.

Infra-slow brain dynamics as a marker for cognitive function and decline.

Functional magnetic resonance imaging (fMRI) enables measuring human brain activity, . Yet, the fMRI hemodynamic response unfolds over very slow timescales (<0.1-1 Hz), orders of magnitude slower than millisecond timescales of neural spiking.