Consciousness obliterated

Birbaumer and Kubler have a paper in Clinical Neurophysiology on the idea that completely locked-in patients essentially slip off into unconsciousness once they become completely locked-in.

Objective: To investigate the relationship between physical impairment and brain–computer interface (BCI) performance.
Method: We present a meta-analysis of 29 patients with amyotrophic lateral sclerosis and six patients with other severe neurological diseases in different stages of physical impairment who were trained with a BCI. In most cases voluntary regulation of slow cortical potentials has been used as input signal for BCI-control. More recently sensorimotor rhythms and the P300 event-related brain potential were recorded.
Results: A strong correlation has been found between physical impairment and BCI performance, indicating that performance worsens as impairment increases. Seven patients were in the complete locked-in state (CLIS) with no communication possible. After removal of these patients from the analysis, the relationship between physical impairment and BCI performance disappeared. The lack of a relation between physical impairment and BCI performance was confirmed when adding BCI data of patients from other BCI research groups.
Conclusions: Basic communication (yes/no) was not restored in any of the CLIS patients with a BCI. Whether locked-in patients can transfer learned brain control to the CLIS remains an open empirical question.
Significance: Voluntary brain regulation for communication is possible in all stages of paralysis except the CLIS.

They examined 29 ALS patients (+ 6 others) who had been trained on a P300 based BCI system prior to the onset of completely locked-in syndrome. Once CLIS set in, they were no longer able to communicate using the system. Literature related to two other non-invasive techniques were used in addition to the P300 based system - low cortical potentials and sensory-motor rhythms. While performance across the board was "usable" (66% success is hardly usable, but I digress), once completely locked-in, patients' performance dropped to chance (except for one individual).

I have a better hypothesis. Use of an EEG based system becomes impossible once completely locked in. EEG relies on large scale, detectable changes in millions of neurons. Locked-in syndrome likely results in large scale changes to cortical topography, due to the lack of feedback - both reinforcing and resultant - resulting in slow wave potential differences unique to this, what might be called 'normalized', state. Nevertheless, an interesting and somewhat calming idea - no pain or negativity, you just drift off into nothingness.

The logical follow-ups are to take this up and down a level. As anti-fMRI as I am (not too strongly, but I think the studies waaay overstate their significance usually), throw them in the magnet and condition different modalities on different answers. Given a multiple choice question, choice A = imagine seeing fireworks, choice B = imagine hearing a train whistle, choice C = imagine throwing a baseball, etc. Just in testing the ability to before these imagined tasks should be enough to assess their ability to respond to a command. Then to provide some very rudimentary, slow communication, use the above association technique. And by down a level, I of course mean single unit recording.

A final thought. Since language is so tightly tied to the motor system, it is possible that communication becomes obfuscated by some severe, hybrid aphasia. If that is the case, the question becomes whether consciousness relies on language. And if that is the case, how does that change the way we see animals, robots and babies (or baby animal robots!). Just something to think about the next time you hippie liberal academics are smoking up at the drum circle. :P

Required reading

I think I mentioned it here before, but everyone in BCI should read The Diving Bell and the Butterfly. Phil Kennedy made me read it back during my days and Neural Signals Inc, and while it isn't particularly stirring or eloquently written, the time you take reading it forces you to take the perspective of a locked-in patient. Looks like they have made a movie out of the book, and Slate has the review (spoiler: the reviewer liked it). (IMDb link) Netflix subscribers can save it to their queue so that it is added when available on DVD (I just did).

Locked-in

BoingBoing picked up on a Mind Hacks post on the topic of Locked-In Syndrome. Locked-In Syndrome refers to a condition caused by any number of disorders or injuries which leave a patient mentally intact, but unable to communicate with the outside world. Essentially, these people are prisoners in their own minds. I've worked with several of these people during my time with Phil Kennedy and John Donoghue, and know this is generally a misnomer.

Most Locked-in patients retain some ability to communicate, using either eye blinks, directional gaze, or binary interfaces to signal intent (especially true for patients in BCI clinical trials, since consent is needed). These folks are generally referred to as 'partially locked-in'. Many conditions eventually lead to becoming 'fully locked-in', such as ALS or mitochondrial myopathy. When people ask why we want to control a simple cursor, this would be a prime example. Even reliable binary control without supervision would be a huge improvement over the current state of affairs.

So, while I know the juicy bits come from robotic arms and exoskeletons, let's keep it grounded. The main reason prosthetic control, cursor control, and switches are worked on all at once is that we have some understanding of limb control by the nervous system. I guess you can consider limb control more 'natural', or more crystallized in the motor system's organization by the time these disorders and injuries are relevant.

They mention Jean-Dominique Bauby, who wrote the book The Diving Bell and the Butterfly while locked-in, using eye blinks. It is a great read, and I would say it is essential for anyone in BCI that hasn't read it, should.