Apparatus for applying Transcranial Magnetic Stimulation (TMS) to an individual, wherein the apparatus comprises: a head mount for disposition on the head of an individual; and a plurality of magnet assemblies for releasable mounting on the head mount, wherein each of the magnet assemblies comprises a permanent magnet, and at least one of (i) a movement mechanism for moving the permanent magnet and/or (ii) a magnetic shield shutter mechanism, for selectively providing a rapidly changing magnetic field capable of inducing weak electric currents in the brain of an individual so as to modify the natural electrical activity of the brain of the individual; wherein the number of magnet assemblies mounted on the head mount, their individual positioning on the head mount, and their selective provision of a rapidly changing magnetic field is selected so as to allow the spatial, strength and temporal characteristics of the magnetic field to be custom tailored for each individual, whereby to provide individual-specific TMS therapy, to assist in diagnosis or to map out brain function in neuroscience research.