What strenght magnetic field can be applied to the human brain?

Question

For anyone familiar with transcranial magnetic field, or electriciy in general, is it safe to place one tesla of electrical field right next to the skull?

Answer 1

TMS (Transcranial Magnetic Stimulation) usually uses about 2 Tesla. The 2 Tesla on the coil surface is estimated to carry over to approximately 0.5 Tesla in the brain. The strength of stimulation is not the only issue however, it is the manner in which the stimulation is delivered. Thus, a 3T MRI (which is quite common for use with humans) has no (known) effect on the brain, and stronger MRIs (up to 12T to my knowledge) are in use with animals with no expected impact on brain function.

All effects of TMS are theorized to reverse - meaning that the brain is supposed to go back to normal. Many remain skeptical.  

Answer 2

Probably not.  The strength of MRI scanners, in which the magnet is a foot or two away from the head, is generally 1.0 - 1.5T.

Answer 3

None.