An intrinsic neuronal manifold underlies brain-wide hierarchical organization of behavior in C. elegans

Large-scale neuronal recordings in various species have revealed behavior-related activity patterns. Surprisingly, these activities are distributed across brain regions, including sensory areas. However, their origins and functions are incompletely understood. Using whole-brain imaging in freely behaving C. elegans, we discover that such distributed brain activity is dominated by a low dimensional manifold, corresponding to the major action sequence of C. elegans. The manifold originates largely from intrinsic dynamics, with minor contributions from movement-induced sensations. We discover a new function of the manifold: to gate the activity of a large number of neuron classes. This gating constrains them to selectively encode faster time-scale motor patterns during specific brain states. We therefore propose that one principle function of brain-wide dynamics is to enable hierarchical organization of behavior: information about major actions is broadcast via a distributed manifold, to enable nesting of granular motor patterns within those major actions.