Magnetic field measurement in brain tissue

Transcranial magnetic stimulation (TMS) has been used in many researches due to its non-invasive feature and it was shown to have several potential therapeutic effects. Rats are often used as an animal model to mimic similar effects in humans. However, differences in outcomes may exist between the two species. One of the major differences between animals and humans is the affected area in brain stimulated by TMS. Thus, how the actual distribution and magnitude of induced magnetic field affect rat brains is significantly desired but still remains uncertain. In this study, the magnitude of magnetic field in ex-vivo rat brain tissue was measured at various depths in order to understand the actual attenuation of the magnetic field in the brain tissue. The results show that the magnitude of the magnetic field decreases exponentially with respect to the depths of the brain tissue.