The purpose of the following study was to employ bioinformatics technology to examine the 3D structure of the calcium-binding domains in the protein synaptotagmin, the so-called gatekeeper of neurotransmission (1). Sites were sought which permit interaction between the world of the self and the world of the brain. The study was based on the dualist-interactionist hypothesis of the late Nobel-laureate Sir John Eccles who, in his book “How the Self controls its Brain” (2), persuasively argues for the existence of such interaction sites between the physical brain and the non-physical “self”; sites he called quantum microsites. Sir John Eccles recognized that quantum interactions at such sites could be used to both affect behavior and affect perception of the physical world. Because such interactions are achieved through manipulation of probability density fields rather than movement of physical particles, they avoid potential conflict with any of the physical conservation laws. The cerebral cortex houses clusters of neurons devoted to specific motor and sensory tasks. The junctions between these neurons are called synapses, and they consist of phospholipid membranes and protein complexes. At the synapse, the axon of the pre-synaptic neuron ends in a bouton, which usually connects with a dendritic spine of the post-synaptic cell. The bouton contains synaptic vesicles awaiting entry of calcium ions triggered by the arrival of nerve impulses. Calcium entry stimulates fusion of the vesicles with the end membrane of the bouton causing release of their cargo of neurotransmitter. The calcium-binding protein, synaptotagmin, triggers rapid fusion events characteristic of normal neural activity. The incoming calcium ions covalently bind seven oxygen atoms. Six of the oxygen atoms are located in two loops of synaptotagmin’s calcium-binding domains. Electrostatic charges surrounding the Ca2+ ions in the domains promote interaction with phospholipid molecules in the end-membrane of the bouton. The two loops position the Ca2+ ions so that they lie at the extreme end of synaptotagmin ready to interact with the negatively charged phospholipid, phosphatidylserine. The seventh oxygen atom which completes the coordination sphere of the Ca2+ ion is located in the charged head of the phosphatidylserine molecule. This seventh Ca-O bond is an ideal quantum microsite. It has the correct dimensions, being no larger than the size of a hydrogen atom. Its manipulation in the physical world would result in perceived perturbation in the non-physical world of wave-fields. Furthermore, its manipulation in the non-physical world could either enhance or inhibit the probability of neurotransmitter release in the physical world and, thereby, regulate neural activity. The non-physical soul would interact with a vast number of such microsites in the brain. Specific centers within the brain would be regulated in order to control particular thought processes. Eccles suggested that neural columns in the cerebral cortex are centers where differentiated interaction could occur. One way to further substantiate Eccles’ dualist-interactionism will be through advances in synapse and neural network research. References (1) Fernandez-Chacon, Konigstorfer, Gerber, Garcia, Matos, et al. (2001). Nature, 410, pp 41-49.(2) Eccles, (1994). How the self controls its brain. New York – Berlin, Springer-Verlag.