So, if I understand correctly they're using Hodgkin-Huxley LIF neurons but trained end-to-end in a graph neural network. Through training to reproduce the neural data, the network learns the underlying connectivity of the neural system?

This seems very cool, but I'm surprised this kind of thing attracts VC money! I'm also skeptical how well this would scale due to the inherently underdetermined nature of neural recordings, but I've only skimmed the PDF so may be missing their goals and approach.