An apparatus for generating a representation of a portion of a brain for use in transcranial magnetic stimulation ("TMS") comprising: a processor for performing a process encoded on a computer readable medium, wherein the process includes the steps of: generating an actual representation of a head surface of a head; generating an idealized representation of the head surface; combining the actual and idealized representations to form a visualization surface, wherein the visualization surface is representative of a portion of the brain within the head at a depth beneath the head surface; and providing for display of the visualization surface, characterized in that the combining step further comprises: weighting the actual and idealized representations with first and second weightings, respectively, wherein the first and second weightings are a function of the depth and wherein the sum of the first and second weightings equals one and each of the first and second weightings is not less than zero or more than one, and wherein the first weighting decreases as the depth increases and the second weighting decreases as the depth decreases; combining the actual and idealized representations weighted by the first and second weightings, respectively, to generate an unscaled visualization surface; and scaling the unscaled visualization surface based on the depth to generate the visualization surface. a processor for performing a process encoded on a computer readable medium, wherein the process includes the steps of: generating an actual representation of a head surface of a head; generating an idealized representation of the head surface; combining the actual and idealized representations to form a visualization surface, wherein the visualization surface is representative of a portion of the brain within the head at a depth beneath the head surface; and providing for display of the visualization surface, generating an actual representation of a head surface of a head; generating an idealized representation of the head surface; combining the actual and idealized representations to form a visualization surface, wherein the visualization surface is representative of a portion of the brain within the head at a depth beneath the head surface; and providing for display of the visualization surface, the combining step further comprises: weighting the actual and idealized representations with first and second weightings, respectively, wherein the first and second weightings are a function of the depth and wherein the sum of the first and second weightings equals one and each of the first and second weightings is not less than zero or more than one, and wherein the first weighting decreases as the depth increases and the second weighting decreases as the depth decreases; combining the actual and idealized representations weighted by the first and second weightings, respectively, to generate an unscaled visualization surface; and scaling the unscaled visualization surface based on the depth to generate the visualization surface. weighting the actual and idealized representations with first and second weightings, respectively, wherein the first and second weightings are a function of the depth and wherein the sum of the first and second weightings equals one and each of the first and second weightings is not less than zero or more than one, and wherein the first weighting decreases as the depth increases and the second weighting decreases as the depth decreases; combining the actual and idealized representations weighted by the first and second weightings, respectively, to generate an unscaled visualization surface; and scaling the unscaled visualization surface based on the depth to generate the visualization surface.