Interesting paper on WBE
Conclusions
It appears feasible within the foreseeable future to store the full connectivity or even
multistate compartment models of all neurons in the brain within the working memory of a
large computing system.
Achieving the performance needed for real‐time emulation appears to be a more serious
computational problem. However, the uncertainties in this estimate are also larger since it
depends on the currently unknown number of required states, the computational complexity
of updating them (which may be amenable to drastic improvements if algorithmic shortcuts
can be found), the presumed limitation of computer hardware improvements to a Moore’s
law growth rate, and the interplay between improving processors and improving
parallelism16. A rough conclusion would nevertheless be that if electrophysiological models
are enough, full human brain emulations should be possible before mid‐century. Animal
models of simple mammals would be possible one to two decades before this
Discussion
As this review shows, WBE on the neuronal/synaptic level requires relatively modest
increases in microscopy resolution, a less trivial development of automation for scanning and
image processing, a research push at the problem of inferring functional properties of
neurons and synapses, and relatively business‐as‐usual development of computational
neuroscience models and computer hardware. This assumes that this is the appropriate level
of description of the brain, and that we find ways of accurately simulating the subsystems
that occur on this level. Conversely, pursuing this research agenda will also help detect
whether there are low‐level effects that have significant influence on higher level systems,
requiring an increase in simulation and scanning resolution.
There do not appear to exist any obstacles to attempting to emulate an invertebrate organism
today. We are still largely ignorant of the networks that make up the brains of even modestly
complex organisms. Obtaining detailed anatomical information of a small brain appears
entirely feasible and useful to neuroscience, and would be a critical first step towards WBE.
Such a project would serve as both a proof of concept and a test bed for further development
Gradual replacement
Scanning might also occur in the form of gradual replacement, as piece after piece of the brain
is replaced by an artificial neural system interfacing with the brain and maintaining the same
functional interactions as the lost pieces. Eventually only the artificial system remains, and
the information stored can be moved if desired (Morevec, 1988). While gradual replacement
might assuage fears of loss of consciousness and identity26 it appears technically very
complex as the scanning system not only has to scan a living, changing organism but also
interface seamlessly with it (at least on the submicron scale) while working. The technology
needed to achieve it could definitely be used for scanning by disassembly.
Gradual replacement is therefore not likely as a first form of brain emulation scanning (though in practice it may eventually become the preferred method if non‐destructive scanning is not
possible).
It is sometimes suggested that extending the brain through interfaces with external software
might achieve a form of transfer where more and more of the entire person is stored outside
the brain, possibly reaching the point where the brain is no longer essential for the composite
person. However, this would not be brain emulation per se but rather a transition to a posthuman state
http://www.fhi.ox.ac.uk/brain-emulation-roadmap-report.pdf
