Passing of Time

Here is a nice review in the New York Times on recent work with the BrainGate. I think it's interesting to note here that for the cost and effort, there wasn't a spectacular outcome (although there was no disaster, either), but it's so sci-fi that people are dying to throw money at it.

I wrote a term paper on many of these issues, and my basic conclusion is that people are not going about motor cortical implants in the right way. The neuroscience is pretty clear, actually - put as many electrodes as you can in the brain, and your brain will figure out how to use them. What's not clear are the technical details - how long can an implant last and give a good signal, how can it be powered, how can transmissions be made wirelessly, what are the risks for infection, what kind of device will be controlled and how can it be robust enough to be controlled constantly? It will be interesting to see if there are any breakthroughs here in the next few years. If technology comes around, we could have some very exciting work ahead of us figuring out how the brain manages to figure out how to use the system to which it's connected. So when I say the neuroscience is clear, I mean it's clear from an engineering point of view. With respect to understanding the underlying mechanisms of learning and cognition, it's awfully grim, it seems.

Passing of Time

Here is a nice review in the New York Times on recent work with the BrainGate. I think it's interesting to note here that for the cost and effort, there wasn't a spectacular outcome (although there was no disaster, either), but it's so sci-fi that people are dying to throw money at it.

More On Sensory Substitution

I've recently been doing some thinking about sensory substitution, which is a very fun and seemingly neglected area of neuroscience. With tactile-visual substitution, would it be possible to get color? I think the way to do this would be to take three color channels and feed them all to different tactile areas - would people ever experience color qualia from this? I have no idea! But I kind of want to try it!

Here are some links for our reference:

• http://www.seeingwithsound.com/sensub.htm
• This is a great little page, with lots of general sensory substitution information.
• http://kaz.med.wisc.edu/Publicity/FAQ.html
• This is the webpage of one of the central researchers in the tactile-visual substitution studies at Wisconsin, with Bach-y-Rita
• http://www.wicab.com/technology/scientific_publications.html
• This is Bach-y-Rita's company

"Bionic Man"

At the talk that I went to last week, people eluded to some sort of human artificial limb research that I hadn't heard about. I'm pretty sure this is it, and I have no idea how it works yet, but it looks awfully cool, doesn't it?

Alva Noë

I have a hunch that Alva Noë really knows what he's talking about. I should probably read his book Action in Perception, where he makes the claim (maybe?) that perception is not established by activating certain parts of the brain, but rather by the "lawful connection of perception and action", which makes a lot of sense. One of the big issues in consciousness, for me at least, is that certain parts of the brain seem to just be associated with certain modalities. But why should vision be visual, how does that part of the brain know that its visual? By an action-type argument, we're able to make a connection between how we act, that is, moving around in the world, or manipulating objects in the world, and how we interpret this, that is vision. Perhaps once this is established, other sensory-substitution type stories will make sense, that is, explain why certain non-visual information, e.g. tongue stimulation will produce visual stimuli. What quality of that information is inherently visual as opposed to inherently auditory? If we glean "visual" information reliably from the environment, does that mean that it will always have a visual quality to it? Hmm.

Procrastinating

Right this moment, I am trying to write a paper applying parts of Patricia Churchalnd's Neurophilosophy to the VITE model, as described by Bullock & Grossberg in 1988. Problematically, I feel like I don't have a whole lot to say about the VITE model, as it's kind of an old version of the model and none too exciting a decade and a half after it's been developed. And yet, I am supposed to discuss whether it is at the correct grain of analysis.

Anyway, doing so I discovered a neat blog that is trying to apply VITE to a robot arm, which seems like a really good idea. I hope that more people realize that their intellectual struggles have a warm home in the world wibe web.

As far as my adventures, I went to see Lee Miller come give a talk at MIT, which appeared as though it may have been hosted by Emilio Bizzi, although I can't be certain, because I was late due to the very, very cold nature of the day and the very, very big nature of the McGovern Institute. I wish I understood more of it, but the big idea seemed to be the high correlation between neurons in Motor Cortex and muscle activation as recorded through chronic EMG electrodes. I didn't know people implanted that sort of thing, but it seems useful, especially if you're aiming at stimulating the arms that you have if you're paralyzed. Of course, there's still the "recruitment problem", which is that when you stimulate a muscle, the larger, fast-fatigable muscles are recruit more quickly, which is the reverse of what takes place when muscles function normally. Overcoming this problem is non-trivial, and there are also apparently problems with getting muscle fusion, or tetanus, at low enough frequencies. Unfused muscle movement is tantamount to twitching a lot, which is not the smooth movement that we're all familiar with.

It's also dawning on me that if I ever hope to be a "motor guy" I'm going to have to learn some hardcore anatomy and physiology of muscles, and also the spinal cord, in serious detail. We'll see.

Oh, and next time, I'll figure out consciousness.

Useful Resource

MIT has one of the best Cognitive Science style programs in the country, and being MIT, they decided that their course resources should all be online. They don't all have the relevant materials online, but the syllabi and links to reading are generally there, and sometimes lecture notes, too. Particularly interesting is noting the differences between Introduction to Neural Networks at MIT and Principles & Methods of Cognitive & Neural Modeling (CN 510) at BU, in which I am currently enrolled. I think I might be a little more pleased if there were more of a consensus here about what is the best way to go about, oh, teaching an introductory course in neural network type stuff.

Going to graduate school has some unpleasant properties that are akin to religion, in that you kind of choose one approach to whatever you're going to study and then kind of ignore all the rest. My opinion of religion can be summarized in that there are N religions, so all things being equal, you have a 1/N chance of just being completely wrong. I think the same thing applies here to a certain extent, and that if something isn't part of the curriculum in my department, I should at least know what it is. And what's even stranger is that my department seems to agree - each year there is a huge conference here at BU covering a huge array of relevant studies, not just what's in our syllabus. But if it's important enough to show up at a conference sponsored by my department, then why do we have such a high level of redundancy in the courses here as opposed to covering this other material? Mysteries abound. I'm pretty sure that similar things are taking place at other universities, but in truth, I have no idea.

Consciousness

So recently I've come to discover that what I mean by "understanding consciousness" is different from what other people mean. Of course, this isn't exactly a surprise, but I still want to clarify what I mean. I think that it's been pretty clearly established that the brain is crucial for consciousness, whatever you think consciousness is (and in animals that have brains). That is to say, if I stimulate the right parts of your brain, you get certain conscious percepts, and if I stimulate an apple, you get no conscious percept at all. Or, if you stimulate someone else's neurons. Or if you stimulate the wrong neurons in your brain. What is it about neurons in V1 that lead to a percept? Is it their pattern of connections to other neurons, or is it some intrinsic quality about that set of neurons itself?

Come to think of it, I don't even know what layers are stimulated when you perceive things in V1, but let's work it through, I guess. Here is some background on V1. It would be convenient to say things like "Layer 6 only projects to lower cortical regions, so if stimulating it leads to a conscious percept then this arises from either Layer 6 or the lower cortical regions", but I think that the canonical A connects to B discourse is probably false.

I know that some people think that the focus shouldn't be so much on neurons, but rather on global activation, that developing a theory of consciousness should start from what we can observe, eg, fMRI type patterns of activation, as opposed to what we cannot observe, eg, quantum phenomena in microtubules. But I don't know how this is going to actually help us understand consciousness on a scientific level, that is, why stimulating in V1 yields a visual percept, whereas stimulating in M1 does not.

I mean, you can always look at broad patterns of connectivity, and say, in obnoxious form, V1 gives visual percepts because it is connected to the eyes. This sort of ties back to a Jeff Hawkins type story, of the cortex identifies patterns, and as such identifying visual patterns simply is a visual percept. Of course, this is equally unsatisfying. But the goal here is to frame the questions underlying consciousness in a way such that they can be investigated.

A lot of this, I feel, ties in to development - do babies have visual percepts? We assume so, but when are these developed? Is it innate? We know that ocular dominance columns develop in utero, are these actually visual percepts? Of course, this is also more useless questions with no clear path to investigate them.

In the meantime, you can go read more about this from smarter people than me, and watch some lectures on the subject which are pretty basic.