Every human brain has an individual, intricate pattern of 86 billion neurons. If science can map it, immortality is within reach.
A cave drawing of a woolly mammoth in the Asturias region of northwest Spain has a single internal feature: a broad red heart. This work of art, at least 14,000 years old, likely depicts a successful hunt and bloody wound. The detection of a pulse, the protection of respiration, and the beating of a heart have all helped to distinguish a piece of meat from a living being since the dawn of time.
As understanding of the brain’s function in consciousness grew and technology made it possible to use devices to control the heart and lungs while a patient was on life support, the basic relationship between breathing, heartbeat, and life itself began to shift. Today, we distinguish between life and death based on the presence or absence of brain activity. That makes sense because, unlike other organs, the brain is vital to you, the person, to your own distinct qualities of identity, memory, intelligence, and subjective experience of the world.
To better understand how the brain underpins selfhood, we must first comprehend its complex form; its complicated structure at the level of neuron connections. After all, studying biological structure has shown the nature of several different types of life. Plants thrive because their large leaves are ideal for converting light energy into essential chemical energy. Similarly, eyes, whether human or insect, enable light from one’s surroundings to be converted into electrical signals inside the nervous system. These impulses hold data that represents characteristics of the surrounding world. However, when it comes to the relationship between structure and function, the brain has remained a mystery. They are much more complex than other organs with basic functions, such as the eyes, hearts, or even the hands. These organs can now be replaced surgically. Even if a brain transplant were possible, you couldn’t literally exchange your brain for another person’s and hold the same mind. A brain replacement hypothesis is a logical fallacy.
What is it about the brain that produces unique experiences?
A person’s brain structure is primarily influenced by their experience in the womb and their particular genetic code when they are born. Experience helps to imprint specific changes on the brain’s neural connectivity as we age, increasing connections in certain places while decreasing them in others, accumulating reroutes upon reroutes as a person ages and learns, acquiring information and experience. There are also shifts in the frequency of current links. These processes are particularly apparent in twins, whose brains are surprisingly identical when they are born. Their brains diverge as they evolve, learn, and experience the world, and their basic self become increasingly distinct.
Essentially, this mechanism produces memory, which is so basic that it expresses itself implicitly in every element of our sense of self. Memory is needed also for our unconscious awareness of movements required for riding a bike, speaking a phrase, or even walking. Incredibly, hypothermia patients who have suffered hours of clinical death due to a lack of both heart and brain activity will achieve complete recovery, showing that neural electrical activity alone is not needed for memory preservation in the brain.
While anatomical regions tend to serve relatively specific roles, memory is not created, preserved, or recalled within the activity of any single brain region. Certain structures, such as the amygdala and the hippocampus, perform important roles, however, searching for memory in a single region is simply impossible. It would be like trying to listen to Beethoven’s Fifth by just hearing the strings (duh duh duh, duuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu Instead, memory, in its broadest sense, is contained in the uniqueness of the connective tissue of the brain, known as the connectome. The connectome is made up of the entire network of neurons as well as all of the connections between them, known as synapses. It is argued that, at its heart, ‘you are your connectome.’
Thus, elucidating the entire brain circuitry is a key to unlocking the correspondence between the connectome and memory. When considering the sheer complexities involved, tracing the wiring at this scale is no simple job. According to some figures, a cubic millimetre of brain tissue comprises about 50,000 neurons and an impressive number of around 130 million synapses. An entire human brain, on the other hand, is more than 1 million cubic millimetres in size and comprises approximately 86 billion neurons, which is roughly equal to estimates of the number of stars in our galaxy.
The most important amount is the total number of synaptic interactions, which is a mind-boggling c100 trillion. Only after determining the possible routes that electrical neural signals will take through these connections will it be possible to fully understand the patterns of behaviour that are essential to memory and subjective experience.
Obtaining connectomes could help address fundamental questions about the relationship between neurons and behaviour. I asked Jeff Lichtman, a Harvard University neuroscientist and visionary connectomicist, what we could do with a human connectome if we could replicate it, and he said the benefits would be enormous. We could, for example, create much more efficient treatments for neurocognitive conditions like schizophrenia or autism, which are believed to be triggered by miswiring, but we still don’t know how.
Lichtman’s study was motivated by the discovery that, through organisms, the wiring diagram of the brain shifts as individuals grow and evolve over their lives. His main inspiration, however, is to map the unknown reaches of the mind imprinted in the connectome data itself. In this regard, he compared the connectome to genomics. He acknowledged that having a complete human connectome would be equivalent to having a full genome, opening up a world of exploration that we can’t even imagine right now.
Simpler versions of connectomes from other organisms, on the other hand, have already aided research. The Allen Institute for Brain Science in the United States, for example, has mapped the circuitry of an entire mouse brain, demonstrating how different types of neurons link various anatomical regions. A partnership at the Janelia Research Campus, involving Google scientists and based on the Howard Hughes Medical Institute in Ashburn, Virginia, mapped a huge, central region of the fruit-fly connectome at the level of individual neurons; the feat took more than 12 years and at least $40 million.
Even before these impressive achievements, pioneering researchers mapped the entire connectome of the roundworm, Caenorhabditis elegans, in the 1980s – all 302 neurons and approximately 7,600 synapses – fueling studies for years. Complex simulations of behaviour on the roundworm connectome are revealing the coordinated activity patterns that underpin the wriggling movements.
Across organisms, synchronisation and alignment of neural signals between seemingly distant brain regions within a connectome serve as a scaffold for the execution and memory of organised sequences of events. When young birds learn their songs, for example, they encode, store, and retrieve the sound patterns they hear from other birds in different chains of neurons, which in turn trigger sequences of muscle movements that produce the same sonic patterns. There are currently at least 20 ongoing studies examining the human connectome and its function in memory, all of which are organised by the Connectome Coordination Facility of the National Institutes of Health in the United States.
However, mapping a connectome at the level of single neurons in a living animal is currently difficult. Instead, animal brains must be removed, perfused with a fixative such as formaldehyde, and cut up as many times as possible before being structurally examined to locate and track individual neurons. To accomplish this, different microscopy techniques are used to record the properties of each new slice. After that, electrical flow patterns can be estimated from various neuron types and connections that excite or inhibit other neurons. It is vital that the extracted brain be accurately preserved in order to retain its intricate, complex connectome until it is cut up.
It is currently doubtful that any human brain has been preserved with its entire connectome intact. After death, our brains degrade much too easily. Without oxygen-rich blood supply, there is a substantial reduction in metabolic activity, which is the collection of chemical reactions that keeps an organism’s cellular life going. When brain cells stop metabolising, irreversible structural damage caused by a lack of fresh oxygen will begin in as little as five minutes. To mitigate the damage incurred by slicing up a brain for connectome mapping, the brain must be preserved as soon as possible.
So, in order to keep the exact structure of the entire connectome, you need a preservation approach that keeps every single neuron and each of its synaptic connections in place – a necessity that must be met 100 trillion times over for a single person.
The consequences of a human brain-preservation technique capable of preserving the entire connectome are profound. If you are your connectome, identified by all of your memories and essences imprinted in its structure, then you are ultimately preserved. You are your connectomic self.
In theory, the argument implies the possibility of avoiding death.
In 2010, a group of neuroscientists banded together due to a common interest in this concept, resulting in the formation of the Brain Preservation Foundation (BPF). Ken Hayworth, a senior scientist at the Janelia Research Campus, is the BPF’s president and co-founder. He told me over the phone that he wanted to collaborate with scientists to make brain protection a feasible choice for terminally ill patients. ‘I know someone in a hospital who is dying, and there is simply no other choice for them right now,’ he explained. ‘If no one advocates for this practise, it will almost definitely never happen… When the time comes for me to face a terminal illness, I would want this choice.’
Soon after its establishment, the BPF began offering a $100,000 cash prize, donated by Israeli tech entrepreneur and poker player Saar Wilf, for new connectome preservation methods. The competition was divided into two stages based on brain size, with a small-mammal prize and a large-mammal prize. The challenge was issued to anyone willing to undertake the enormous effort involved, along with a set of comprehensive assessment criteria involving molecule-level electron microscopy scans.
And who better to take on the task than the cryonics movement, which is dedicated to cryopreserving terminally ill people (or only their brains) immediately after death in the hopes that they can be thawed after storage in liquid nitrogen in a future with a cure. Hayworth hoped that the prize money would enable them to show the efficacy of their preservation techniques. ‘The award was intended to inspire cryonics providers to “put up or shut up,” he explained.
Cryonics, on the other hand, had yet to take off by 2018. Instead, scientists from 21CM (for 21st-Century Medicine), a private cryobiological research company in California focused on preserving frozen specimens, won both levels, claiming the preservation award after demonstrating intact connectomes in a preserved rabbit brain and then in a preserved pig brain. The award-winning technique was developed by Greg Fahy, the founder of 21CM and an accomplished cryobiologist, and Robert McIntyre, a graduate of the Massachusetts Institute of Technology (MIT). The method, which was previously known as aldehyde-stabilised cryopreservation but is now known as vitrifixation, is based on the use of a fast-acting fixative called glutaraldehyde, which was previously used as a disinfectant, in conjunction with other chemicals that cause the brain to enter a vitrified physical state, hence the name vitrifixation.
For futurists, the process spelled a revolution because the connectomes were found to be intact after cryogenic freezing to at least -135°C. At this temperature, all metabolic and biological processes stop, allowing for infinite preservation for hundreds, if not thousands, of years with no sign of rotting. Assuming the relevant logic regarding the connectomic self and the function of memory is right, vitrifixation will ultimately allow you to be preserved in a state of suspended animation forever.
McIntyre has long believed that it is important to preserve not just the physical brain structures but also the memory stored within those structures. After all, human development is based on the transmission of knowledge over time through great leaps of creativity. The first such leap occurred with the development of oral language, and the second occurred with the development of written language, which could more reliably preserve knowledge, theoretically for longer periods of time. ‘Can you imagine going back in time and telling anyone in a time before written language that one day it will be possible to turn everything they can say into carvings in stone that will last aeons for someone in the far future to discover?’ They wouldn’t have believed you,’ McIntyre explained over the phone.
He was initially enthralled by the possibility of using neuroscience to remove memories from minds, which contain much more knowledge about experiences and events than any other existing method of preservation, such as writing, audio, or even video. After hearing recordings of his grandmother talking about travelling by covered waggon from Oklahoma to Texas, among other historic life experiences, he wondered if it was possible to retrieve a memory from a brain – basically a “living memory,” the first-hand insight of actually being there – the knowledge you’re lacking after reading, say, a history textbook, as an example.
He visited a neuroscience lab as an undergraduate, where researchers rejected the theory as ridiculous and difficult to accomplish. Instead, he preferred a theoretical approach to the problem, using artificial intelligence (AI) to solve it. He attended MIT and, in 2014, accompanied his father to a cabin in the wilderness to finish his PhD dissertation. They went for a walk that changed his life. Apart from AI, his father asked him how he could directly salvage memory when carrying handguns in case of rattlesnake assault. They came to the conclusion that it was better to leave it to the future to build innovations that are largely unimaginable to us now, while retaining the substrate of those memories, the connectome itself.
If connectomes contain memories that can be relived, their meaning is unparalleled. Consider the experience gained by soldiers after witnessing life-changing experiences during a battle. It’s one thing to read about world wars in textbooks or even personal memoirs, but no source of knowledge carries the specificity that a living memory of witnessing war firsthand does. McIntyre believes that deep insight will provide humanity with the intelligence, foresight, and judgement needed to steer it away from an unsustainable, species-ending path.
There was finally a strategy for immortalising memories in the connectome that BPF scientists might lobby for, thanks to vitrifixation. Unfortunately, the fixative agent used in vitrifixation to perfuse the vascular system is completely and directly lethal. You couldn’t immortalise memories without killing the person who created them.
If you go through the process after getting your last thought, you will be sedated with a general anaesthetic. Your chest will then be opened and your arteries will be attached to a perfusion apparatus. After being exsanguinated and pumped with glutaraldehyde, it will diffuse through your brain’s capillaries and stop all metabolic activity, killing you almost instantly while binding proteins form a solid, long-lasting meshwork in your brain. Your brain will then be perfused with antifreeze to avoid damage before being removed and cryogenically preserved indefinitely.
It seems to be a no-brainer, to make a bad pun. The cure (death) is worse than the disease: living memory is destroyed. However, both Hayworth and McIntyre agree that, while vitrifixation is lethal, it does provide a kind of immortality if the essence of someone can be searched for all relevant knowledge and then somehow transferred to an artificial medium; one that, from a practical perspective, effectively replaces the brain. Crucially, when ‘running,’ this medium will have to accurately and appropriately perform the neural activity patterns that sustain one’s memory, identity, and experience in order to invoke their specific consciousness.
This is referred to as ‘whole-brain emulation.’ After all, why would brains be made entirely of biological material? And, if minds can operate on a network of connections, can’t they be “substrate independent,” in the sense that all the knowledge required for a mind is found in the arrangement and operation of those connections, rather than any given substrate?
Despite the fact that the related research is still in its infancy, several important advances have been made. Many methods imagine computational mediums involving digital knowledge spaces for simulating brain function. Brain-computer interfaces currently enable thought-controlled operation of prosthetic machines. Furthermore, real neural prosthetics are replacing brain cells directly. In the truest sense, it is form to act. Furthermore, multimillion-dollar tech companies like Neuralink, Kernel, Building 8, and DARPA are forging even more advanced links between mind, brain, and machine, raising the likelihood of such whole-brain emulation.
So, how can you go about simulating something as astronomically complex as a brain? Two techniques have gained momentum. The first, and most common, approach entails creating a digital simulation of the connectome and its operation, probably at the molecular level, and then releasing it into cyberspace. The simulation in this grand scheme is so complete and precise that it becomes an emulation of the emergent property of a person’s personality, memory, awareness, emotions, and feelings in the same way that we actually understand subjective perception to be an emergent property of someone’s active biological brain. According to one interpretation, this future includes the possibility of living in a futuristic, artificial environment where you interact with other emulated minds. The second solution entails implanting the simulated brain into a prosthetic self, creating the ultimate cyborg in which every aspect of you is synthetic. Your mind could live in the real world with a fully artificial body in this situation.
However, you might only make it to the end of your life with your lifeless, vitrifixed brain and whatever remains of your corpse. Even if the ‘new you’ is a complete, conscious emulation with the same memories, identity, emotions, and subjective self, there is a good likelihood that it would not be you. Rather, a doppelgänger: a clone that is similar in any way. After all, it should be possible to build several instances of a new you; the question is, which one is you? Is that all? Memories, personality, and conscious subjective perception can thus be compared to a song that can be played on any instrument capable of producing neural notes.
Alternatively, concepts of personal identity and survival can come to surround you as a continuous property rather than a binary, yes/no choice. When you get old, you’re just partly the same person you were when you were born, but the younger you never dies while the old you appears out of nowhere. Essentially, we must wonder whether we are doomed to remain as the molecules that we currently are. As we learn more about consciousness and connectomes, our understanding of them will evolve dramatically. In my conversations with Lichtman, Hayworth, and McIntyre, I heard a similar message: while the prospect of reanimation is the current beachhead, by the time we achieve it, human knowledge, culture, and technology would have changed.
When I pressed McIntyre on this, he simply said, ‘If brains can do it [for example, recover after clinical death in cardiac arrest survivors], we can do it – and we will find out how.’ McIntyre, like Lichtman (who calls himself a “presentist” rather than a “futurist”), drew an analogy to the discovery of DNA. ‘When it was found 70 years ago, no one knew what to do about it, and now…’ ‘This is not going to happen any time soon,’ Hayworth says. However, ‘humanity will eventually succeed in understanding the brain and creating the required scanning and simulation technologies… humanity will eventually find it out.’
With such far-reaching possibilities comes a great deal of responsibility. The possibility of avoiding death by vitrifixation raises several ethical issues that, despite systematic consideration, remain unanswered: for example, would there be equal opportunity to partake in the process or would it be limited to those who can afford it? How can one’s memories be protected from tampering, loss, or theft? Who will be in charge? Under what conditions, and by whom, could memories in a virtual connectome be accessed?
One problem seems to be less contentious: the possibility of making vitrifixation available to terminally ill patients as soon as it is possible.
After winning the $100,000 award, McIntyre and his former MIT roommate Michael McCanna formed a contentious venture capital firm. Their company is called Nectome, and it is a brain bank project. According to the company’s website, the primary aim is to conserve and basically store human memory. So far, Nectome has received over a million dollars in support and has been awarded a $960,000 federal grant from the US National Institute of Mental Health for ‘whole-brain nanoscale preservation and imaging.’ The federal grant expressly cites the prospect of a “commercial opportunity in providing brain preservation.”
Nectome now has a list of at least 30 donors, each of whom has contributed $10,000. The operation, which has never been carried out on a living person, is legally legal in five US states under existing physician-assisted suicide laws for terminally ill patients. In reality, Nectome’s only human vitrifixation was performed on the brain of an elderly woman whose body was donated to McIntyre by the body-donation organisation Aeternitas Life. The procedure was carried out just 2.5 hours after the woman’s death, resulting in one of the best-preserved brains in the world.
It’s no wonder that Nectome has sparked some heated debate. Various media outlets falsely interpret the donations as “deposits” for suicide procedures, which McIntyre categorically rejects. ‘Those donors wanted to be among the first backers.’ When I asked, he said, ‘We don’t sell any brain preservation services.’ However, in reaction to the controversy, MIT terminated its continuing neuroscience relationship with the firm in 2018.
The sobering reality is that anyone aspiring to become a Nectome client may be in for a long wait. The assertion that the self can be found in the connectome is still far from established, and there might never be a way to decide if consciousness may exist in a system. Getting vitrifixation performed may lead to nothing more than suicide at a high financial expense.
No one should rush out to get their brains preserved if there is no guarantee that it will succeed, according to Hayworth. Instead, he claims that he really wants to advance science. ‘Of course, it may not work, but people are dying.’ [Vitrifixation] has also been shown to effectively maintain the structures and molecules that modern neuroscience claims encode us. As a result, terminal patients should have the choice to take the risk if they so choose.’
From Lichtman’s current views to Hayworth and McIntyre’s futurist optimism, one sentiment remains consistent: the connectome has the potential to have a significant effect on our future in uncertain yet important ways.