larval MP1 neuron MP1b neuron VFB:FBbt_00001601 FBbt:00001601 Medial-most of the two bilateral MP1 neurons found at the midline, anterior to the posterior commissure (Schmid et al., 1999). fly_anatomy.ontology Doe et al. (1988) distinguish the MP1-progeny by referring to them as left or right. However, as this changes the identity of the cell depending on whether the right or left side of the animal is observed, we have adopted a nomenclature based on reference to the midline.