On the non-uniqueness of the inverse MEG problem

It has recently been shown by Fokas and coworkers that if the brain is approximated by a homogeneous sphere, magnetoencephalographic measurements determine only the moments of one of the three scalar functions specifying the electrochemically generated current in the brain. In this letter, we show that this is a generic limitation of MEG. Indeed, this indeterminancy persists in the general case that the sphere is replaced by a starlike conductor.