1. An apparatus for assessing consciousness comprising: an electroencephalographic sensor for collecting electrical signals from firing neurons within a patient's brain; a neural stimulator for promoting a localized excitation of neurons within the patient's brain at a location and time using transcranial magnetic stimulation; and an electronic computer for receiving the electrical signals from the electroencephalographic sensor and executing a stored program to: (i) measure neural activity indicated by the electrical signals following the localized excitation of neurons by the neural stimulation, (ii) analyze the neural activity to determine how well the patient's brain is integrating information by evaluating spatial propagation of excitation of neurons, and (iii) provide an indication of consciousness is based on an assessment of information integration; and wherein the electronic computer is configured to measure an extent of the spatial propagation of excitation of neurons from a location of localized excitation by evaluating a combination of strength and location of neural current sources over multiple locations within the brain and map greater spatial propagation to greater consciousness.