EEG consumer BCIs spanked by the Schwartzinator

Forbes has a fun little story on the state of consumer BCIs that hits on the major consumer players, but also throws real BCIs researchers John Wolpaw and Andy Schwartz into the fray. Each echos the officially sanctioned position of their respective scalp electrode versus implanted microwire/fancier probe electrode camp.

I prefer to call this the Head-Computer Interface versus Brain-Computer Interface debate. I try to be even keeled on the subject. EEG is obviously a worthwhile endeavor because there's none of that messy surgery involved, and thus appeals to a very large audience (at least in the near term). Hey, if you get a signal that can be controlled by the user reliably and with an acceptable level of precision, you have something useful. BUT, EEG is a degraded, garbled, sloppy signal prone to nearly limitless interference sources. Anything that can bork an implanted BCI can bork an EEG-based system, but EEG throws the doors open to the world because you are essentially wearing an antenna (or several).

One major problem with EEG is the fallacy that somehow destroyed information can be recovered by some form of fancy filtering. This is simply not so. Think of the electrode as a point of convergence for all electromagnetic signals of a measurable intensity. Even after narrowing frequency bands and implementing funky probabilistic decoders, any squiggle can be the convergence of several squiggles of indeterminable sources. In other words, at a specific time, a signal of amplitude +5 can be two signals of +4 and +1, -2 and +7, or 5 signals of +1-4-2+3+7. And don't even start with harmonics.

The second problem is population size. I know we like to think that motor cortex responds to only movement. It makes life easier. What life? Life in La-La-Land. MI responds to visual stimuli, movement preparation, auditory stimuli, imagined movements, movement related words (heard, internally rehearsed or spoken), reward, attention, cutaneous and proprioceptive feedback, and a bunch of other factors I'm not even mentioning. Until the impact of these influences is understood and quantified, there will not be any BCI that translates the neural activity for "move my arm to point x,y,z". EEG will never have the fidelity to isolate the differences feedback has at the single neuron level, so the nature of the recorded signal will never allow the 'direct' mapping of neural activity to output. That is, the activity that once gave rise to movement can never be harnessed with an acceptable degree of control to recreate the movement. Yes, I am using the word never. Never. There, I said it again.

Like I said, this isn't an attack on EEG, just reality. Different uses for different technologies. I can drive a car on a road. That doesn't mean I can drive a road, or that a road has no use.

Hochberg article in NEJoM

Leigh has an article in this month's New England Journal of Medicine related to The Project. Required reading, of course.

Walk like an Egyp... human

As mentioned yesterday in jest, learning from what we cannot do is just as important as important as making new rules and associations. This appears to be the case with motor strategies as well. For some reason, I never really considered the fact that it takes a wiggling, squirming baby years to develop significant non-stereotyped, coordinated movements until Gerry Loeb mentioned it at an NIH workshop (along with a doomsday, dismal progress report on the state-of-the-art). Sure, it makes sense for things we ascribe to general 'knowledge', in the folk psychology sense, but just moving seems so fundamentally biological that we somehow set it aside as 'natural'.

Movements that minimize discomfort and maximize muscle efficiency is the focus of a robotics lab at MIT. (Why do their profs always have the most wicked cool pictures?) I think there is a special place in every movement-related BCI scientist's heart for robotics. Sure, work from the big names, like Reza Shadmehr, is great, but there's something about seeing decoding ideas performed by a cold, hard steel that just appeals to the geeky sci-fi kid in us all.

There was a great article on Cognitive Daily on the subject of detecting artificial movements. It looks like there's still some use for old-fashioned psychology experiments yet. Not surprisingly, this has been looked at on a more neuroscientific level, and localized, in part, to the Superior Temporal Sulcus (STS).

Interesting paper

Georgopoulos has a new review out. I haven't had time to sink my teeth into it yet (that's what Friday is for), but the abstract sounds fascinating.

"Local shaping of function in the motor cortex: Motor contrast, directional tuning"

Pubmed Linky.

The Bayes of our lives

Somehow the paper below slipped past me. I will start posting a list of new papers every Friday, so if YOU see something worth noting in a journal, post it in the comments to this weekly paper list entry.

The dynamics of memory as a consequence of optimal adaptation to a changing body
Nature Neuroscience pp779 - 786

Konrad P Kording, Joshua B Tenenbaum & Reza Shadmehr

Published online: 13 May 2007 doi:10.1038/nn1901Abstract Full text PDF (449K) Supplementary Information

This covers some interesting territory related to how the nervous system operates on a "best guess" basis. This is important because true real-time operation is an adaptively poor model - too many processing delays due to sloppy, gooey biology make for easy predator bait.

A few more papers...

Of course I post a list of papers the same day as J Neurosci is updated.

Involvement of the Basal Ganglia and Cerebellar Motor Pathways in the Preparation of Self-Initiated and Externally Triggered Movements in Humans
from Journal of Neuroscience current issue by Purzner, J., Paradiso, G. O., Cunic, D., Saint-Cyr, J. A., Hoque, T., Lozano, A. M., Lang, A. E., Moro, E., Hodaie, M., Mazzella, F., Chen, R.

Processing of Temporal Unpredictability in Human and Animal Amygdala
from Journal of Neuroscience current issue by Herry, C., Bach, D. R., Esposito, F., Di Salle, F., Perrig, W. J., Scheffler, K., Luthi, A., Seifritz, E.

Multisensory Integration Shortens Physiological Response Latencies
from Journal of Neuroscience current issue by Rowland, B. A., Quessy, S., Stanford, T. R., Stein, B. E.