Eli5: how neurons activities are detected and used to manipulate mechanical hands?

Question

There was a video(forgot the source) where scientists use a device to detect brain signals and use those signals to manipulate mechanical hands in a paralyzed patient.

I know there are devices that can detect brain signals, but how scientists can tell if those signals are responsible for like moving fingers or moving wrist?

In: 2

Answer 1

I believe there won’t be a specific region in brain that tell which fingers will move in a specific way when there are neuron activities(in the region), am I right?