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Forecasting Whole-Brain Connectomics – A Kurzweilian Approach – Article by Dan Elton

Forecasting Whole-Brain Connectomics – A Kurzweilian Approach – Article by Dan Elton

Daniel C. Elton, Ph.D.


Editor’s Note: In this article, U.S. Transhumanist Party Director of Scholarship Dr. Daniel C. Elton describes the recent advances in mapping the connectomes of various organisms, as well as the technological advances that would be needed to achieve effective human whole-brain emulation. Given extensive discussion of these subjects among U.S. Transhumanist Party members, including at the Virtual Enlightenment Salon of September 27, 2020, with Kenneth Hayworth and Robert McIntyre, it is fitting for the U.S. Transhumanist Party to feature this systematic exploration by Dr. Elton into what has been achieved in the field of connectomics already and what it would practically take for human whole-brain emulation to become a reality. As Dr. Elton convincingly illustrates, this possibility is still several decades away, but some steady progress has been made in recent years as well.

~ Gennady Stolyarov II, Chairman, United States Transhumanist Party, March 7, 2021


The connectome of an organism is a map of all neurons and their connections. This may be thought of as a graph with the neurons as nodes and synaptic connections as edges. Here we take the term ‘connectome’ to refer to the graph and the underlying electron microscopy images of the neurons, which contain much more information. However, to successfully simulate an organism’s brain using a connectome, more information will be needed.  Retrieving a detailed scan of an entire brain and mapping all the neurons is a prerequisite for whole-brain emulation. In their landmark 2008 paper, “Whole Brain Emulation: A Roadmap“, transhumanists Anders Sandberg and Nick Bostrom construct a detailed “technology tree” showing the prerequisite technologies for realizing whole brain emulation:

Tech tree from Sandberg & Bostrom, 2008

In this article, we focus on the “scanning” component along with part of the “translation” component, namely neuronal tracing. By plotting technological progress on a logarithmic plot, similar to how Kurzweil does, we attempt to forecast how many decades away we are from being able to scan an entire human brain (and trace/segment all neurons to determine the connectome).  Of course, while Kurzweilian projections have been known to hold (most famously for Moore’s law), we caution that the start of a logistic function can look like an exponential function. In other words, exponential trends can and often do plateau. As any investment advisor would say, “past returns are no guarantee of future results”.

The complete connectome of the nematode worm (Caenorhabditis Elegans) was published in 1986. A complete set of images of the fruit fly (Drosophila melanogaster) was published in 2018. However, all of the neurons and their connections have not yet been segmented or traced. In January 2020 researchers published the connectome of the central brain of the fruit fly, containing 25,000 neurons, which to my knowledge is the largest connectomics dataset published to date.

I thought it would be fun/interesting to plot the progress of connectomics over time and try to extrapolate out any trend observed. So, I did a literature search for all studies to date which either traced or segmented neurons and marked out synapses in electron microscopy data:

[1] D. D. Bock, et al. “Network anatomy and in vivo physiology of visual cortical neurons”, Nature 471 (7337) (2011) 177–182. doi:10.1038/nature09802. [link]
[2] K. L. Briggman, M. Helmstaedter, W. Denk, Wiring specificity in the direction-selectivity circuit of the retina, Nature 471 (7337) (2011) 183–188. [link]
[3] D. J. Bumbarger, M. Riebesell, C. Rodelsperger, R. J. Sommer, System-wide rewiring underlies behavioral differences in predatory and bacterial-feeding nematodes, Cell 152 (1-2) (2013) 109–119. [link]
[4] C.-Y. Lin, et al., A comprehensive wiring diagram of the protocerebral bridge for visual information processing in the drosophila brain, Cell Reports 3 (5) (2013) 1739–1753. [link]
[5] S. ya Takemura, et al., A visual motion detection circuit suggested by drosophila connectomics, Nature 500 (7461) (2013) 175–181. [link]
[6] M. Helmstaedter, K. L. Briggman, S. C. Turaga, V. Jain, H. S. Seung, W. Denk, Connectomic reconstruction of the inner plexiform layer in the mouse retina, Nature 500 (7461) (2013) 168–174. [link]
[7] N. Kasthuri, et al., Saturated reconstruction of a volume of neocortex, Cell 162 (3) (2015) 648–661. [link]
[8] A. A. Wanner et al., 3-dimensional electron microscopic imaging of the zebrafish olfactory bulb and dense reconstruction of neurons, Scientific Data 3 (1). [link]
[9] K. Ryan, Z. Lu, I. A. Meinertzhagen, The CNS connectome of a tadpole larva of Ciona intestinalis (l.) highlights sidedness in the brain of a chordate sibling, eLife 5 (2016) [link]
[10] S.-y. Takemura, et al., A connectome of a learning and memory center in the adult Drosophila brain, eLife 6 (2017). [link]
[11] K. Eichler, et al., The complete connectome of a learning and memory centre in an insect brain, Nature 548 (7666) (2017) 175–182. [link]
[12] C. S. Xu, et al., A connectome of the adult drosophila central brain (preprint) [link]
[13] L. K. Scheffer, et al., A connectome and analysis of the adult drosophila central brain, eLife 9 (2020). [link]
[14] J. S. Phelps, et al., Reconstruction of motor control circuits in adult drosophila using automated transmission electron microscopy, Cell 184 (3) (2021) 759–774.e18. [link]

Next I plotted most of the data for the number of neurons versus the date of publication:

Next I did linear regression on the (year, log(# neurons)) data which is equivalent to fitting an exponential function to the data. (The reason for fitting the data in this way was to avoid the bias that occurs when fitting an exponential function with least-squares regression that leads to the larger values on the y axis being fit more accurately than smaller ones.) After doing the linear regression I extrapolated it forward in time.

The projection for the fruit-fly connectome (2024) seems about right. If anything, we may see it slightly sooner. It will be interesting to see how much longer it will take before we have physically realistic models of the fruit fly and fruit-fly behavior.  U.S. Transhumanist Party member Logan T. Collins has advocated for  building biophysically and behaviorally realistic models of insects to better understand nervous systems. For one thing, interesting neuroscience experiments may be performed on a simulated “virtual fly” much faster and easier than on a real fly (for instance, certain neurons may be removed or manipulated, and the effects on the virtual fly’s behavior observed).  A project to produce the mouse brain connectome is underway, and again, the date extrapolated to — 2033 — seems plausible if the funding for the project continues. Beyond that though, I have very little idea how plausible the projections are!

Here are some numbers that show the challenges just with scanning the entire brain (not to mention segmenting/tracing all the neurons accurately!).

Assuming an isotropic voxel size of 20 nm, it is estimated that storing the images of an entire human brain would require 175 exabytes of storage. It seems we are approaching hard drives which cost about 1.5 cents per gigabyte. Even at those exorbitantly low prices, it would still cost $2.6 billion to store all those images!

The volume of the human brain is about 1.2 x 10^6 cubic millimeters. The Zeiss MultiSEM contains either 61 or even 91 electron beams which scan a sample in parallel. According to a Zeiss video presentation from April 8th, 2020, it can scan a 1×1 mm area at 4 nm resolution in 6.5 minutes. Assuming a slice thickness of 20 nm, a single such machine would require 742,009 years to scan the entire brain!

X-ray holographic nano-tomography might be the path forward …


Dan Elton, Ph. D., is Director of Scholarship for the U.S. Transhumanist Party.  You can find him on Twitter at @moreisdifferent, where he accepts direct messages. If you like his content, check out his website and subscribe to his newsletter on Substack.

Is the Soul Digital or Analogue? – Article by C. H. Antony

Is the Soul Digital or Analogue? – Article by C. H. Antony

logo_bgC. H. Antony


I am probably not the ideal Transhumanist; I do believe that I have a soul, that it is more the essence of me than the sum of my neurons and how they interact with each other to create my thoughts, and that it is an extremely fragile thing. Should I die and preserve myself to be revived at a later date, I fear that I would never know of the success or failure of that endeavor. That a living breathing thinking person who acts like me and reasons like me will rejoin society is not in question; I only wonder that I might miss it as my essence passes on into some other form of existence… or worse – not. I do not believe that a digital substrate will, in fact, carry my soul on uninterrupted.

I want to explore the question of the soul for a moment. In The Singularity is Near (2005), Ray Kurzweil stated that the Calculations Per Second of the human brain are in the vicinity of 10 to the 14th power, based on the assumption, and rightly so, that each neuron in the brain could be considered a digital on/off or 1/0. Around six years ago, we began seeing articles describing microtubules in the axons of the neuronal cells that seemed to have quantum properties I freely admit to not understanding. I cheerfully invite anyone to correct me on this, but it seems that while the neuron either fires or doesn’t as it communicates with the neighboring cell, the microtubule seems to exist in a sort Schrödinger-like state of possibilities – like a multiplexing wire that might convey one piece of information by doing so at a particular combination of wattage, voltage, and resistance, then convey a completely different set of instructions with another combination of the same. It seems to me that if every neuron is operating in a digital on/off state, then 1014  computations per second (CPS) are likely given the average number of neuronal cells in the human brain, and if that number might be horribly wrong because of what we now know of the activity within the axon – then this suggests that superposition state of neural activity might very well be the essence of our consciousness and, if interrupted, could be lost and what remains would be something else only a comfort to those we would have left behind.

I agree that an entirely biological existence is not only a seriously limiting factor in our future development, but also something we are destined to outgrow and will do so. However, I would say that my ideal manifestation of this is a seamless combination of man and machine. Medical technology could eliminate all the senescence we suffer to the point where the next logical step is enhancement over a timeless organic form. I, for one, would hate to live for hundreds of years and gather all the knowledge and experience of those times only to die because of some future equivalent of a drunk driver. That in itself is good enough reason to fortify my existence any way I can. If that means that my body must be replaced with an artificial one, so be it. But, I want to keep my squishy, limited, fragile brain! I want my cake and to eat it, gleefully, with a nearly indestructible form that doesn’t need the cake, won’t get fat from it, and still let’s me enjoy the flavors and textures as I do now. I want to enjoy all the many hedonistic joys freely and with only greater precision than my limited biological form can experience.

I believe we’re seeing this very trend emerge and that the collective instinct of man is far more ready to accept an enhanced human/cyborg than uploading oneself to a purely artificial substrate. Evidence of this can be seen in the amazing promise of Elon Musk’s Neuralink project, the recent X-Prize challenge for a robot avatar, and the many amazing advancements in prosthetic limbs and organs. As I previously stated, medical technology will soon overcome senescence, allowing our tissues to go on indefinitely, so to essentially cure our brain of degeneration, enhance it with a neural mesh, and go about our lives in a perfected cybernetic body akin to Ghost in the Shell: Altered Architecture is probably a pretty good direction to be steering ourselves as Transhumanists. It’s also the most likely Next Step, if you will, considering how well society is conditioned for these themes. I would certainly feel more comfortable with my own enhanced mind in a perfect and durable body that can be easily upgraded and modified as the centuries pass.

So now I ask the members of this community to bring their thoughts here. What is your ideal existence?

C. H. Antony is a member of the U.S. Transhumanist Party. He may be contacted here