How might someone be revived from a preserved brain?

Revival scenarios have to be taken with a grain of salt, because predicting future technology is notoriously difficult. However, it does not seem like we need any fundamentally new technology to revive people from their preserved brains, just refinement of existing technology.

We could revive people using mind uploading, which involves making a high quality digital recreation of the brain and then simulating it on a computer. We already have the first stages of technology to do this, as we can preserve small sections of brain tissue, scan them with an electron microscope, trace out the neuronal connections using computer vision and manual human tracing, and even simulate the resulting system in simple models today. For examples, see Briggman, Helmstaedter, and Denk, 2011, Briggman and Bock, 2012, and Hayworth, 2012.

It is no longer implausible to imagine preserving a whole human brain, and then a few decades from now either scanning it nondestructively, in a future molecular-resolution MRI scanner, or cutting it into a million slices with an automated machine, and digitizing it in parallel using multibeam electron microscopes (destructive scanning), and then running the digitized brain on a very powerful computer. Though applying these techniques to a whole large animal brain is presently beyond our ability, we have been using destructive scanning techniques (FIBSEM, etc.) on very small animal brains for a few years now (zebrafish today, flies very soon) , though we don’t yet know how to extract memories from these digitally uploaded brain scans, as we haven’t yet cracked the long-term memory code for neocortex. But we do seem very close to understanding memory in hippocampus, our most ancient type of cortex, also called archecortex, an area of the brain used for storing short-term memory. For more, see computational neuroscientist Edmund Rolls’ publications. Getting to scans of larger animal brains, and extracting memories from these scans (simple ones in model organisms, at first) is a matter of engineering and incremental improvement over our current techniques. Specifically, we need faster computers, better brain preservation techniques, faster electron microscopes, better models in computational neuroscience of hippocampal and cortical memory, and better algorithms to process the vast amounts of data involved in a human connectome.

We could also revive people by restoring biological function. This may or may not be feasible depending on the exact way in which the brain is preserved. The idea is to reverse the damage done to brain by the preservation method and restore the brain to the same or better healthy biological state it was in before preservation. The restored brain would then be placed in a cloned or robotic body, or the preserved biological body would also be repaired at the molecular level. As preservation methods become more advanced and do less damage to the brain, it will become easier to reverse the damage and revive the brain. The ultimate achievement of this approach would be reversible preservation, where a person could be put into suspended animation and then revived at any time with no complications. Reversible preservation would be immensely useful for many applications such as organ banking, space travel, or emergency medical stabilization.