In particular, pseudo-time ordering identified an activation trajectory that branches out from resting microglia into two activated subpopulations—cells overexpressing GPNMB or such with high levels of HSP90AA1 and IL1B. In addition, quantitative imaging analysis of sPD and control midbrain sections revealed a reduction in microglial branching exclusively in the SN of PD patients [55•]. This evidence concerns the gene IL1B and Parkinson disease.