 The causation of these experiences is problematic. Some aspects of the experience have been deliberately induced by the administration of drugs (see Jansen 1997); this demonstrates that such phenomena can be produced by chemical alterations to the brain, but in most NDE cases no such chemical causes can be identified. Several researchers have concluded that the triggering cause of the NDE is simply the perceived nearness of death. (NDEs have also been experienced by persons who believed they were close to death but were not in fact in any life-threatening situation (K. Augustine 2008,  Other Internet Resources,  see the section on Pam Reynolds).) The specific content of NDEs can be divided into mundane content, in which what is experienced is or resembles typical features of the ordinary world, and transcendental content, portraying “another realm” quite unlike the world of ordinary experience. The source of the transcendental content is problematic, though the cultural variations suggest that a significant role must be assigned to cultural expectations concerning the afterlife.