The paradigm, of course, is the human observer. Too much detail is required to specify a space-time path. Because of the level of abstraction at which observers are defined, in fact it is necessary to work with sets of density matrices rather than with individual states. A Neural Quantum Switch is an entity in the human nervous system which satisfies the definition of a quantum switch and which has switching behaviour strongly correlated with the firing of some neuron. Neural Quantum Switches exist.
Examples are parts of various ion channel molecules, and patches of neural and synaptic membrane.
To attack problem 2, a pattern of elementary localized events is defined in terms of the space-time relations between the events. The information processed by a brain can be perfectly modelled by the pattern of space-time events formed by a set of determinations of statuses of a family of neural quantum switches. Each pattern of determinations of switch status has a set of possible physical manifestations and each manifestation corresponds to a set of sequences of quantum states. A complete mathematical definition of these sets is given. This involves, for example, defining what it means for a localized object to maintain its identity over time.