1. A method of determining displacements of brain areas as a result of tumor formation and of their presentation on an image screen utilizing stereotactic atlases characterized by determining by means of known physical correlations, particularly Hooke's law, a displacement vector u ( r ) for each point of mass of a brain area (P 1, P 2, P 3, P n ) which in an initial state was located at a position described by a position vector (r 1, r 2, r 3, r n ) where the tumor ( 3 ) is now located, which displacement vector may be unambiguously defined by two parameters b, c, whereby the parameters b, c may be derived from the boundary conditions tumor size and tumor type and the displacement vectors u ( r ) are subsequently mathematically calculated and a new position vector ( r 11, r 22, r 33, r nn ) is calculated for each point of mass of a brain area (P 1, P 2, P 3, P n ) as a result of the displacement, thereafter inserting the image of the tumor ( 3 ) as well as the determined displacements with the new position vectors ( r 11, r 22, r 33, r nn ) which took place as a result of the tumor formation, into an anatomic atlas so that the brain areas characterized by the displaced points of mass (P 11, P 22, P 33, P nn ) are now displayed in the actual positions.