This chapter focuses on a special coil for transcranial magnetic
stimulation (TMS) of the monkey brain, to compare induced currents in
the phantom brain elicited by different coils and to confirm that with
coil, focal stimulation is achieved in the monkey brain using positron
emission computed tomography (PET). It is well known that TMS cannot
induce enough currents to activate neurons within a small volume
structure. How the different stimulating coils affect induced currents
are investigated to find out an appropriate size and shape of the coil
for focal stimulation of an animal brain. The measurements of induced
electric fields have shown that stronger, more localized fields were
elicited with monkey coil than with a flat, same-sized, figure-of-eight
coil or with a larger coil for human brain stimulation. Moreover, an
F-fluorodeoxyglucose (FDG)-PET study has shown that localized activation
was really accomplished in the monkey brain with this coil.