Replacing Neurons

August 20th, 2010 in Uncategorized 6 comments

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Imagine: a mad scientist with a ray gun shoots at a neuron somewhere in cortical layer IV of your visual area MT, burning it up in a matter of microseconds (just for fun, imagine also that the ray gun leaves everything else intact).

With one neuron missing, you probably won’t notice any perceptual change. But what if, one by one, all neurons in are MT went AWOL? You’d be stuck with an annoying inability to visually detect motion.

Now imagine that for every cell that our fancy ray gun hits, it replaces it with a magical transistor equivalent. These magical transistors have wires in place of each and every dendrite, a processing core, and some wires in place of axon(s). Naturally, the computational core analyzes the sum of all inputs and instructs the axon to “fire” accordingly. Given any set of inputs to the dendrite wires, the output of the axon wires is indistinguishable from that of the deceased neuron.

We can still imagine that with one neuron replaced with one magical transistor, there wouldn’t be any perceptual change. But what happens when more and more cells are replaced with transistors? Does perception change? Will our subject become blind to motion, as if area MT weren’t there? Or will motion detection be just as good as with the real neurons? I am tempted to vote in favor of “No change [we can believe in],” but have to remain skeptical: there is simply no direct evidence for either stance.

Ray guns aside, it is not hard to see that a computational model of a brain circuit may be a candidate replacement of real brain parts (this is especially true considering the computational success of the Blue Brain Project’s cortical column, which comprises 10,000 neurons and many more connections among them). For example, we can imagine thousands of electrodes in place of inputs to area MT that connect to a computer model (instead of to MT neurons); the model’s outputs are then connected, via other electrodes, to the real MT’s outputs, and ta-da!  Not so fast. This version of the upgrade doesn’t shed any more light on the problem than the first, but it does raise some questions: do the neurons in a circuit have to be connected in one specific way in order for the circuit to support perception? Or is it sufficient simply for the outputs of the substitute to match those of the real circuit, given any set of inputs? And, what if the whole brain were replaced with something that produced the same outputs (i.e. behavior) given a set of sensory inputs – would that “brain” still produce perception?

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Subconscious Security: Our Next Big Life Investment?

August 20th, 2010 in Uncategorized 3 comments

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Have you seen the hit summer movie, Inception, yet? If not, I recommend you to, because it’s mind bottling (Yeah, anchorman_-734679Anchorman’s Ron Burgundy would approve). Either way though, seen it or not, the movie tweaked my curiosity about the ever-growing interaction between technology and our brains, our minds.

In the movie, Leonardo DiCaprio’s character, Cobb, is on a mission to plant an idea into another character’s mind in order to safely, legally, go home to his kids.

Cobb and his colleagues use a PASIV (Portable Automated Somnacin IntraVenous) device to access the target’s mind while he is sleeping on an airplane.

UInception-production-still-4nfortunately for Cobb’s team, the target’s mind has what Cobb calls “subconscious security,” trained mental “projections” set up in his mind to protect it from intruders. To implant the idea, they have to find a way around this security, but how? Will they make it? The movie’s a must-see – watch and find out!

So, how is this far-off movie-world of inception, dream-sharing, and mind-reading relevant, or worthy of discussion at present?

Well, haven’t fMRI results been cluing us in on some of our emotions, conscious or not? In my last post, I discussed how one’s level of empathy correlates with the activity of the ACC (anterior cingulate cortex) as recorded by an fMRI. Whether lab volunteers knew it or not, they (their brains, really) reacted more actively to the pain of those similar to them.

And now, with the rapid succession of advancements in brain-imaging technology, mind-reading and even dream-recording does not seem so unrealistic. “Subconscious security” might actually come in handy if our privacy becomes too vulnerable.

Recent articles (one and two) discuss how researchers at Northwestern University have discovered technology that can be used to “get inside the mind of a terrorist.” In their experiment, they created a mock terror-attack plan with details known and memorized only by some lab participants. The researchers found a correlation between the participants’ P300 brain waves and their guilty knowledge with “100 percent accuracy,” as J.P. Rosenfeld says.

Measuring the waves using electrodes attached to the participants’ scalps, they were able to determine whether they had prior knowledge of, or strong familiarity with, certain dates, places, times, etc.

While TIME writer Eben Harrell notes the threat this type of experiment has on privacy and its clear limitations (“confounding factors” such as familiarity, not because of guilty knowledge but of fond memories, i.e. a hometown), he also notes that interrogations can be more detrimental than these experiments. Accuracy can be improved upon simply by presenting more details to participants.

In her 2008 article, Celeste Biever tells readers how scientists, particularly Yukiyasi Kamitani and his colleagues, have come to analyze brain scans and reconstruct images the lab volunteers had seen in their mind. The scientists believe their work has potential to improve reconstructions to finer focus and even color.

John-Dylan Haynes of the Max Planck Institute in Germany, referred to in Biever’s article, says that the “next step is to find out if it is possible to image things that people are thinking of.” He even considers the possibility of making “a videotape of a dream” in the near future.

However, as Berns points out in an August 2010 article written by Graham Lawton and Clare Wilson, ethical issues canvaswould likely be raised if this brain-imaging technology begins to bind too intimately with advertising and marketing companies. People would probably feel uncomfortable if advertising becomes too knowledgeable of the workings of their minds, perhaps even enticing them to buy things they “don’t want, don’t need, and can’t afford.”

For now though, the advertising approaches using this technology seem innocent enough. With EEG machines, advertisers can determine which designs, words, or advertisements receive certain patterns of brain activity – in other words, receive the most attention from potential buyers.

Not only have EEG machines been used by advertisers, but also by sales companies – for both purposes inspiring and not so inspiring. Starting with the latter, some companies (i.e., Mattel, Emotiv) have sold cheap EEG devices to “mainstream consumers,” particularly gamers. One Californian company, NeuroSky, has built an emotion-detecting device, determining, per se, whether one is relaxed or anxious.

While not completely necessary or inspiring, devices like these are fascinating. I’d like to see what some device thinks I’m feeling, and how accurate it is.

Fortunately, there are inspiring purposes for these EEG devices. As discussed by Tom Simonite in his April 2009 article, those with disabilities or paralysis can use the devices to help control wheel chairs and even type on a computer. One engineer, Adam Wilson, even updated his Twitter using one of these systems (BCI2000): “USING EEG TO SEND TWEET.”

Not only can EEG devices help those with disabilities or paralysis, but prosthetic limbs can also. Professors at the Friedrich Schiller University of Jena, Weiss and Hofmann, discuss in their article that one of their systems allows the brain to “pick up…feedback from the prosthesis as if it was one’s own hand,” easing phantom pain.

DARPA (Defense Advanced Research Projects Agency) has allowed prostheses to advance even more than this, aspiring to bring back to wearers the experience of touch. They awarded The Johns Hopkins University Applied Physics Laboratory (APL) over $30 million to “manage and test the Modular Prosthetic Limb (MPL),” which would canvas2use a “brain-controlled interface” to perform desired actions.

Despite the hurdles along the way (as noted by Andew Nusca in his blog), the lab has released a final design, as described in a reprinted online article. It offers an amazing 22 degrees of motion, weighs the average nine-pound weight of a natural limb and responds to the wearer’s thoughts.

While the blooming relationship between technology and the brain has raised ethical questions about privacy and its use, it has also brought hope and awe to people. Maybe, with the seeming innocence of neuro-marketing thus far and the hope inspired by research and development, we won’t need to turn to “subconscious security” just yet.

Sources:

Reading Terrorists Minds About Imminent Attack: Brain Waves Correlate to Guilty Knowledge in Mock Terrorism Scenarios – Science Daily (reprint)

Fighting Crime by Reading Minds – Eben Harrell of TIME

‘Mind-reading’ software could record your dreams – Celeste Biever of New Scientist

Visual Image Reconstruction from Human Brain Activity using a Combination of Multiscale Local Image Decoders – Kamitani, et. al of Neuron

Mind-reading marketers have ways of making you buy – Graham Lawton and Clare Wilson of New Scientist

Mind-reading headsets will change your brain – Tom Simonite of New Scientist

Prosthesis with information at its fingertips – Weiss and Hofmann of FS University of Jena

DARPA aims to control prosthetic limbs with brain implants – Andrew Nusca of Smart Planet

Thought Control of Prosthetic Limbs Funded by DARPA – Neuroscience News (reprint)

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