I woke up on Saturday to a heartbreaking front-page article in the New York Times about a terminally ill young woman who chooses to freeze her brain. She is drawn into a cottage industry spurred by “transhumanist” principles that offers to preserve people in liquid nitrogen immediately after death and store their bodies (or at least their heads) in hopes that they can be reanimated or digitally replicated in a technologically advanced future.
Proponents have added a patina of scientific plausibility to this idea by citing the promise of new technologies in neuroscience, particularly recent work in “connectomics”—a field that maps the connections between neurons. The suggestion is that a detailed map of neural connections could be enough to restore a person’s mind, memories, and personality by uploading it into a computer simulation.
Science tells us that a map of connections is not sufficient to simulate, let alone replicate, a nervous system, and that there are enormous barriers to achieving immortality in silico. First, what information is required to replicate a human mind? Second, do current or foreseeable freezing methods preserve the necessary information, and how will this information be recovered? Third, and most confounding to our intuition, would a simulation really be “you”?
I study a small roundworm, Caenorhabditis elegans, which is by far the best-described animal in all of biology. We know all of its genes and all of its cells (a little over 1,000). We know the identity and complete synaptic connectivity of its 302 neurons, and we have known it for 30 years.
If we could “upload” or roughly simulate any brain, it should be that of C. elegans. Yet even with the full connectome in hand, a static model of this network of connections lacks most of the information necessary to simulate the mind of the worm. In short, brain activity cannot be inferred from synaptic neuroanatomy.
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