I don't know about you but I consider sticking a needle deep through the brain to be a surgery. I guess the authors are using a more technical definition. No doubt this will help speed up research in labs.

For actual no surgery stimulation of deep brain tissues there's arrays of low powered ultrasound and interferometric transcranial alternating current. And if 4.5 mm deep is the goal-line even the current practice transcranial magnetic stimulation with a butterfly coil can do the job (more awkwardly).