(a, left) Synaptic area of dopaminergic neuron (DAN) innervating the mushroom body in aged PD models (AuxR927G, synjR258Q, or LRRK2G2019S) and with or without GH146-Gal4-driven expression of the wild-type PD gene (aux or synj) or EndoAS75D, respectively. Here, LGALS4 is linked to Parkinson disease.