Something called Transcranial Magnetic Stimulation alters brain activity at about one Tesla (10,000x earth's field).
TMS has been shown to induce euphoria, amnesia, and relieve depression. Unclear what stronger magnetic fields could do. A ten Tesla magnet can levitate a small animal.
I work in this sector, and what you say is correct, however it is important to note that in TMS the fields are pulsed over millisecond time intervals. In doing so they can induce an electric field which can cause neurons to fire. The time varience is crucial. A 3T static field from the magnet of an MR scanner is far less dangerous than a 1T field pulsed in the vicinity of your brain. That is providing that there aren't any ferromagnetic objects close to the MR scanner!
Radiologist here. We regularly image patients in 3T MRI scanners. As long as they don't have certain metal surgical implants, a pacemaker, or metallic foreign bodies, there is no problem.
