Motor-driven advection competes with crowding to drive spatiotemporally heterogeneous transport in cytoskeleton composites*

Particle transport through the cytoskeleton can range from anomalous and heterogeneous subdiffusion to superdiffusion and advection. However, fully understanding the mechanisms by which cytoskeletons induce these different types of transport remains challenging. Here, we combine light sheet microscopy and single particle tracking to elucidate anomalous transport in actomyosin-microtubule composites. We show that particles in these composites exhibit multi-mode transport that transitions from pronounced subdiffusion to superdiffusion at tunable crossover timescales. In particular, we find that increasing actomyosin content enhances superdiffusion at longer time scales via myosin motors inducing ballistic-like contraction, restructuring, and flow of the composites and enhances subdiffusion at shorter time scales via steric entanglements, connectivity, and slow thermal relaxation of cytoskeletal filaments.