In the video game Deus Ex: Human Revolution, neuroscience meets synthetic augmentation in a fascinating and terrifying manner. The game focuses on the war between people who are neurologically augmented, and those who are too principled (or too poor) to seek artificial augmentation.

The question of what makes us human is critical to the story and the path you choose to take in its conclusion. But to what extent are the features of Deus Ex: HR grounded in reality, as opposed to merely science fiction?

Crack for Augs: the Neuropozyne story

In the HR world, the fictional drug Neuropozyne is given to those with augmentations as an anti-rejection drug. Apparently, without Neuropozyne "glial tissue build-up" develops around the augmentation, eventually leading to rejection of the implantation (or Darrow Deficiency Syndrome in the Deus Ex universe). This leads to dependence on the drug for the augmented, giving immense control over individuals by the powerful pharmaceutical company VersaLife, as well as general social chaos as wide swaths of the population find themselves reliant on Neuropozyne in order to maintain control over their own bodies.

Eidos Montreal deserves props for integrating some real neuroscience into an already rich, cohesive narrative. So let's delve into what they got right.

Your nervous system can be divided into what we call the "central" (brain and spinal cord) and "peripheral" (rest of the body) nervous systems. Glial cells are often thought of as the "helper cells" of the peripheral and central nervous systems, supporting the functions of neurons and nerve cells.

In the central nervous system, "glial tissue build-up" does actually exist, in a sense; a process known as "glial scarring" occurs after neurological injury. After damage, a type of glial cell known as astrocytes reacts by changing shape and occupying the area near the injury site, releasing molecules that inhibit regrowth and leading to the formation of a glial scar, in order to keep things nice and stable.

The presence of these astrocytes, as well as the molecules they release, prevents axons from crossing the injury site and re-forming functional attachments. This is one of the main obstacles in spinal cord injury rehabilitation; axons (extensions of neurons that allow communication with other cells) from neurons below the injury initially try to extend and re-connect with neurons on the other side, but are blocked by the scar. We already have a few pharmacological treatments to suppress and treat glial scarring: olomoucine, which reduces numbers of astrocytes and may facilitate axonal regeneration; ribavirin, which decreases the number of active astrocytes; and rolipram, which causes axons to regrow, to name but a few currently-used therapies.

The Neuroscience of Deus Ex: Human Revolution

Astrocytes: helper cells, or scar-inducing little bastards?

However, you can see one problem with the Deus Ex interpretation of biology here; if glial scarring happens after neurological injury to stop regrowth, why do people regain motor control and sensation after nerve damage to limbs, fingers, et cetera? It's because in the peripheral nervous system, the glial make-up is a little different; different types of glial cells help out after an injury, allowing axons to re-grow and make functional connections. So for anything outside the brain and spinal cord: no astrocytes, no "glial tissue build-up", no Neuropozyne necessary, no problem. This means the peripheral augs (see image below) would be a-okay without Nu-Poz.

The Neuroscience of Deus Ex: Human Revolution

Peripheral augs, in red.

As for the augs that implant directly into the central nervous system, glial scarring shouldn't be a problem for them either, as long as they integrated into existing neural networks as opposed to severing wide swaths of axons, and even if glial scarring did occur it wouldn't continuously accumulate but would merely represent a gap in neural circuitry which could be bridged by the implants themselves.

The Neuroscience of Deus Ex: Human Revolution

Central nervous system augs are in dark blue; light blue are augs that may not connect directly to the brain or spinal cord, but are contingent upon other augs that do. These are my best guesses based on the game's docs and wiki, so feel free to send me angry emails about how the Infolink totally jacks into the brain's language centers or something

And as for rejection of these devices by the immune system, our immune system often targets organic biological targets that typically wouldn't be present in synthetic implants. The only remaining immunological targets are the "live neural cells" in HR's version of PEDOT electrodes, but these cells and their connections can be protected from the immune system by a mesh system that's already in use by scientists today. By the way, PEDOT electrodes, minus the addition of live neural cells, currently exist, and their composition may make them useful for human implantation. (On an unrelated note "pedot" is apparently Finnish for "beasts"). Finally, the whole immune system problem can be avoided altogether by using embryonic stem cells, or even stem cells from the implantee themselves to create neurons for HR's PEDOT electrode. So you don't need to be Adam Jensen to get by without Neuropozyne.

The Neuroscience of Deus Ex: Human Revolution

"Yeah, don't worry about that document that describinges someone of your age and blood type whom I've been 'personally observing', andwhich begins with your initials, and about which I'm suddenly acting sketchy…"

All that being said, while continual improvement toward better science in games is both necessary and appreciated, a perfectly accurate game is limited in its freedom to create a novel and exciting fictional world. A careful balance must be struck between realism and fantasy, with scientific accuracy as an ideal, but not always as an attainable goal, especially when story is such a high priority. In a post by lead narrative designer Mary DeMarle intended to justify the inclusion of Neuropozyne in HR, she said, "Including the concept of Neuropozyne in the game did help us to exacerbate the social divides in the game... but it was also important for several other story reasons. First, it gave us a way to clearly illustrate Adam's uniqueness. Second, it made for a cool side quest. And third, it allowed us to make some nice tie-ins to DX1 and a certain drug company that's run by Illuminati members…" And the writers cared enough about scientific accuracy to consult with Will Rossellini, founder of MicroTransponder inc. and a neuroscience PhD student, who has said about his role: "When I volunteered to be a science consultant in 2008, I said, 'Let's imagine where today's research can go in 20 years'... A lot of that science is intertwined with the plot and explained within the game." Demarle has confirmed the importance of Rossellini's scientific input: "Will came along... and ended up opening our eyes to things that we didn't even dream possible." At the same time, "This is a game, so there are certain things that we want[ed] in it that are just wild... We did take some liberties with some things, knowing that we could turn to [Rossellini] and have him... help us make it sound more credible"

While I love the lengths that Eidos Montreal went to integrate real neuroscience into their story, I fully agree that in order to create the type of fictional world one can envision, compromises must sometimes be made in the service of a compelling narrative. As a general heuristic, though, I hope we maintain this trend of improving science in games, as a combination of realism and fantasy enhances a sense of immersion but also a sense of wonder, at both the natural and fictional worlds we find ourselves in.

This article by Ian Mahar originally appeared over at the Thwacke! Consulting Blog. Find Thwacke! on Twitter and Facebook.