The use of the term neurotheology in published scientific work is currently uncommon. A search on the citation indexing service provided by Institute for Scientific Information returns five articles. Three of these are published in the journal Zygon: Journal of Religion and Science, while two are published in American Behavioral Scientist. Work on the neural basis of spirituality has, however, occurred sporadically throughout the 20th century. Keywords for such work include 'deity', 'neurophysiological bases', 'spirituality' and 'mysticism'.