By far the most ambitious neural-prosthesis program involves computer chips that can restore or augment memory. Researchers at the University of Southern California, in Los Angeles, have designed chips that mimic the firing patterns of tissue in the hippocampus, a minute seahorse-shaped neural structure thought to underpin memory. Biomedical engineering professor Theodore Berger, a leader of the USC program, has suggested that one day brain chips might allow us to instantly upload expertise. But the memory chips are years away from testing. In rats.
Discussions of memory chips leave Andrew Schwartz cold. A neural-prosthesis researcher at the University of Pittsburgh, Schwartz has shown that monkeys can learn to control robotic arms by means of chips embedded in the brain's motor cortex. But no one has any idea how memories are encoded, Schwartz says. ”We know so little about the higher functions of the brain that it seems ridiculous to talk about enhancing things like intelligence and memory,” he says. Moreover, he says, downloading complex knowledge directly into the brain would require not just stimulating millions of specific neurons but also altering synaptic connections throughout the brain.
That brings us to the interface problem, the most practical obstacle to bionic convergence and uploading. For now, electrodes implanted into the brain remain the only way to precisely observe and fiddle with neurons. It is a much messier, more difficult, and more dangerous interface than most people realize. The electrodes must be inserted into the brain through holes drilled in the skull, posing the risk of infection and brain damage. They often lose contact with neurons; at any one moment an array of 100 electrodes might make contact with only half that many cells. Scar tissue or blood can encrust the electrode, cells around it might shift their position or die, and electrodes have been known to corrode.
Researchers are testing various strategies for improving contact between neurons and electronics. They are making electrodes out of conducting polymers, which are more compatible with neural tissue than silicon or metal; coating electrodes with naturally occurring glues, called cell-adhesion molecules, which helps cells in the brain and elsewhere stick together; and designing electrode arrays that automatically adjust the position of the electrodes to maximize the reception of neural signals.
At Caltech and elsewhere, engineers have designed hollow electrodes that can inject fluids into the surrounding tissue. The fluids could consist of nerve-growth factors, neurotransmitters, and other substances. The nerve-growth factors encourage cells to grow around electrodes, while the neurotransmitters enhance or supplement electrical-stimulation treatment. Neuroscientists are also testing optical devices that can monitor and stimulate neurons, as well as genetic switches that turn neurons on or off.
To be sure, it's promising work. Terry Sejnowski, a neuroscientist at the Salk Institute for Biological Studies, in San Diego, says the new technologies will make it possible ”to selectively activate and inactivate specific types of neurons and synapses as well as record from all the neurons in a volume of tissue.” That, in turn, might make it possible to build more effective and reliable neural prostheses.
But again, it's a fantastically long way from there to consciousness uploading. Even singularitarians concede that no existing interface can provide what is required for bionic convergence and uploading: the precise, targeted communication, command, and control of billions of neurons. So they sidestep the issue, predicting that all current interfaces will soon yield to very small robots, or ”nanobots.” Remember the 1966 motion picture Fantastic Voyage ? That's the basic idea. But try to imagine, in place of Raquel Welch in a formfitting wet suit, robotic submarines the size of blood cells. They infiltrate the entire brain, then record all neural activity and manipulate it by zapping neurons, tinkering with synaptic links, and so on. The nanobots will be equipped with some sort of Wi-Fi so that they can communicate with one another as well as with electronic systems inside and outside the body.
Nanobots have inspired some terrific ”X-Files” episodes as well as the Michael Crichton novel Prey . But they have as much basis in current research as fairy dust [see ”Rupturing the Nanotech Rapture,”].
Steven Rose has nothing against technoenhancement. The neurobiologist at England's Open University wears eyeglasses and is proud of his titanium knee and dental implants. He says a lot can be done to improve the brain's performance through improved drugs, neural prostheses, and perhaps genetic engineering. But he calls the claims about imminent consciousness uploading ”pretty much crap.”
Rose disputes the singularitarians' contention that computers will soon surpass the brain's computational capacity. He suspects that computation occurs at scales above and below the level of individual neurons and synapses, via genetic, hormonal, and other processes. So the brain's total computational power may be many orders of magnitude greater than what singularitarians profess.
Rose also rejects the basic premise of uploading, that our psyches consist of nothing more than algorithms that can be transferred from our bodies to entirely different substrates, whether silicon or glass fibers or as-yet-unimaginable quantum computers. The information processing that constitutes our selves, Rose asserts, evolved within--and may not work in any medium other than--a social, crafty, emotional, sex-obsessed flesh-and-blood primate.
To dramatize that point, Rose poses a thought experiment involving a ”cerebroscope,” which can record everything that happens in a brain, at micro and macro levels, in real time. Let's say the cerebroscope (hey, maybe it's based on nanobots!) records all of Rose's neural activity as he watches a red bus coming down a street. Could the cerebroscope reconstruct Rose's perception? No, he says, because his neural response to even that simple stimulus grows out of his brain's entire previous history, including the incident in his childhood when a bus almost ran him over.
To interpret the neural activity corresponding to any moment, Rose elaborates, scientists would need ”access to my entire neural and hormonal life history” as well as to all his corresponding experiences. Scientists would also need detailed knowledge of the changing social context within which Rose has lived; his attitude toward buses would be different if terrorists recently had attacked one. The implication of his thought experiment is that our psyches will never be totally reducible, computable, predictable, and explainable. Or, disappointingly enough, downloadable into everlasting new containers.
Perhaps the old joke is right after all: If the brain were simple enough for us to understand, we wouldn't be smart enough to understand it.
Let's face it . The singularity is a religious rather than a scientific vision. The science-fiction writer Ken MacLeod has dubbed it ”the rapture for nerds,” an allusion to the end-time, when Jesus whisks the faithful to heaven and leaves us sinners behind.
Such yearning for transcendence, whether spiritual or technological, is all too understandable. Both as individuals and as a species, we face deadly serious problems, including terrorism, nuclear proliferation, overpopulation, poverty, famine, environmental degradation, climate change, resource depletion, and AIDS. Engineers and scientists should be helping us face the world's problems and find solutions to them, rather than indulging in escapist, pseudoscientific fantasies like the singularity.
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