Dreams of a consciousness measuring device

The New York Times has an excellent article about Giulio Tononi, one of the few neuroscientists trying to understand consciousness in a way that may have a direct practical application – to create a medical device that can tell whether you are conscious or not.

To be honest, I’ve been a bit bored with consciousness, not in an existential sense you understand, but in terms of the science which tends towards tinkering with interesting but possibly inconsequential effects.

The NYT article, however, is completely riveting, as it discusses Tononi’s quest to understand consciousness to the point of building a ‘consciousness meter’.

Although it may sounds fanciful, it could have an important medical application – to help anaesthetists determine when a patient is actually aware of what’s happening to them.

If you’re not familiar with surgery you’d think this was easy enough to determine except for the fact that muscle relaxant drugs are often administered.

This means that even if you’re awake, you can’t communicate the fact, occasionally leading to terrifying cases of people who are conscious but paralysed while operated on.

So ideally, anaesthetists would like a machine that gives a consciousness ‘read out’ from the brain. There is something called the bispectral index, which claims to measure depth of anesthesia, although it turns out not to be a very good guide to consciousness.

Of course, to create a device to measure consciousness, we need to understand its neuroscience, and Tononi has a unique theory he is working on:

Consciousness, Dr. Tononi says, is nothing more than integrated information. Information theorists measure the amount of information in a computer file or a cellphone call in bits, and Dr. Tononi argues that we could, in theory, measure consciousness in bits as well. When we are wide awake, our consciousness contains more bits than when we are asleep.

For the past decade, Dr. Tononi and his colleagues have been expanding traditional information theory in order to analyze integrated information. It is possible, they have shown, to calculate how much integrated information there is in a network. Dr. Tononi has dubbed this quantity phi, and he has studied it in simple networks made up of just a few interconnected parts. How the parts of a network are wired together has a big effect on phi. If a network is made up of isolated parts, phi is low, because the parts cannot share information…

Dr. Tononi argues that his Integrated Information Theory sidesteps a lot of the problems that previous models of consciousness have faced. It neatly explains, for example, why epileptic seizures cause unconsciousness. A seizure forces many neurons to turn on and off together. Their synchrony reduces the number of possible states the brain can be in, lowering its phi.

The NYT piece is a fantastic look into the ideas behind the theory and the exciting possibilities it presents.

Link to NYT on ‘Sizing Up Consciousness by Its Bits’.

7 thoughts on “Dreams of a consciousness measuring device”

  1. I fondly recall integrating the data output of bispectral index monitors when I was working on anesthesia patient monitoring software. Mostly because the monitor didn’t have a test mode, so I had to actually hook myself up to it to generate a test signal.

    Over lunch one day, we played fun biofeedback games, trying to get as low a score as possible (“Bispectral golf”?).

    “Try to think unconscious thoughts. Or not to.”

    Then the company founder (a practicing anesthesiologist) told us how much each disposable sensor cost… we didn’t play that game any more.

    A shame it’s not as effective as had been hoped.

  2. Why Tononi is wrong

    In a recent NY Times article, Tononi chooses to propose a rather sketchily-described “Shannon informational” model to supplant a gamma synchrony model partly on these grounds;

    “Dr. Tononi sees serious problems in these models. When people lose consciousness from epileptic seizures, for instance, their brain waves become more synchronized. If synchronization were the key to consciousness, you would expect the seizures to make people hyperconscious instead of unconscious, he said. “


    Jouny et al (2010) http://www.ncbi.nlm.nih.gov/pubmed/19910249 surely should have suggested that this is premature closure, with an INCREASE in signal complexity – that is, decline in synchrony – associated with seizure

    Ours study of ECOG data (electrodes directly attached to the cortex, not on the scalp) confirms this. Sleep signal is least complex/disordered under PCA, first component explains 97%, awake is next, with 93% explained by the first component, while seizure has just 63% explained by first component.

    We will duly submit these results to a responsible peer-reviewed journal

    Sleep signal is least complex/disordered under PCA, first component explains 97%, awake is next, with 93% explained by the first component, while seizure has just 63% explained by first component.

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