Data representing logical computations along four stages in the brain

A key challenge in neuroimaging remains to understand where, when and now
particularly how human brain networks compute over sensory inputs to
achieve behavior. To study such dynamic algorithms from mass neural
signals, we recorded the magnetoencephalographic (MEG) activity of
participants who resolved the classic XOR, OR and AND functions as overt
behavioral tasks (N = 10 participants/task, N-of-1 replications). Each
function requires a different computation over the same inputs to produce
the task- specific behavioral outputs. In each task, we found that
source-localized MEG activity progresses through four computational stages
identified within individual participants: (1) initial contra-lateral
representation of each visual input in occipital cortex, (2) a joint
linearly combined representation of both inputs in midline occipital
cortex and right fusiform gyrus, followed by (3) nonlinear task-dependent
input integration in temporal-parietal cortex and finally (4) behavioral
response representation in post-central gyrus. We demonstrate the specific
dynamics of each computation at the level of individual sources. The
spatio-temporal patterns of the first two computations are similar across
the three tasks; the last two computations are task specific. Our results
therefore reveal where, when and how dynamic network algorithms perform
different computations over the same inputs to produce different
behaviors.