Apparatus for applying Transcranial Magnetic Stimulation (TMS) to a patient, the apparatus including a head mount for disposition on the head of a patient; and a plurality of magnet assemblies for releasable mounting on the head mount, wherein each of the magnet assemblies includes a magnet for selectively providing a rapidly changing magnetic field capable of inducing weak electric currents in the brain of a patient so as to modify the natural electrical activity of the brain of the patient; 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 patient, whereby to provide patient-specific TMS therapy, to assist in diagnosis or to map out brain function in neuroscience research.