A unilateral coil for transcranial magnetic stimulation of a head, the coil comprising: a base portion including multiple spaced apart stimulating elements , said multiple spaced apart stimulating elements nested within one another so that they are configured to carry electrical current in a first direction, wherein said multiple spaced apart stimulating elements comprises a first base portion group and a second base portion group spaced apart from said first base portion group , wherein said second base portion group is configured to be positioned on a parietal section and said first base portion group is configured to be positioned on a temporal section on only one side of the head; and a return portion including multiple spaced apart return elements , wherein each of said multiple spaced apart return elements corresponds to one of said multiple spaced apart stimulating elements , wherein said multiple return elements comprises a first return portion group of protruding return elements for return of current from said first base portion and configured in use to protrude above the head, and a second return portion group of contacting return elements for return of current from said second base portion and configured in use to be located adjacent the head, wherein the second return portion group is spaced apart from said first return portion group , and wherein each of said multiple spaced apart return elements is configured to carry electrical current in a second direction, wherein said second direction is an opposite direction to said first direction, and wherein said return portion is spaced a distance away from said base portion , and wherein said coil is configured to induce a supra-threshold field at deep structures of a brain region on the one side of the head. a base portion including multiple spaced apart stimulating elements , said multiple spaced apart stimulating elements nested within one another so that they are configured to carry electrical current in a first direction, wherein said multiple spaced apart stimulating elements comprises a first base portion group and a second base portion group spaced apart from said first base portion group , wherein said second base portion group is configured to be positioned on a parietal section and said first base portion group is configured to be positioned on a temporal section on only one side of the head; and a return portion including multiple spaced apart return elements , wherein each of said multiple spaced apart return elements corresponds to one of said multiple spaced apart stimulating elements , wherein said multiple return elements comprises a first return portion group of protruding return elements for return of current from said first base portion and configured in use to protrude above the head, and a second return portion group of contacting return elements for return of current from said second base portion and configured in use to be located adjacent the head, wherein the second return portion group is spaced apart from said first return portion group , and wherein each of said multiple spaced apart return elements is configured to carry electrical current in a second direction, wherein said second direction is an opposite direction to said first direction, and wherein said return portion is spaced a distance away from said base portion , and wherein said coil is configured to induce a supra-threshold field at deep structures of a brain region on the one side of the head. <EOS>