NDEs and OBEs reflect altered states of consciousness (ASCs) that can experimentally be studied via modern brain scanning and electroencephalographic methods. Scientific literature presents convincing evidence for brain-based explanations of NDEs and OBEs. The disturbance of normal multisensory integration in the temporo-parietal junction (TPJ) of the cerebral cortex via over- or under-excitation or via misalignment of sensory inputs is the most plausible and experimentally confirmed origin of OBEs. NDE generation seems to be based on information exchange in various neural networks of the brain involving different sets of brain areas for different NDE themes. When NDE themes explicitly refer to a first-person perspective, the TPJ is an excellent candidate for a major contribution to NDE occurrence. When visual phenomena are part of the NDE theme, the occipital cortex can be assumed to be strongly involved. There is a clear connection of NDEs with ASCs and the TPJ as a brain center that significantly contributes via brain-wave activity to the regulation of states of consciousness.