Sitting at the bed side of a loved one who has slipped into a coma and simply reading a story, talking about the day, or just holding hands most likely feels like a pointless and endless effort for the recovery of the vegetative patient. There can only be the glimmer of hope that maybe they can sense your presence, but there is no definitive way to know for sure if your interactions are falling on a deaf brain.

We all can make personal judgments that we are conscious right here and right now. But, making this sort of judgment for another individual when their interactions with the world are limited or apparently absent is not only challenging, but also ethically dangerous as your decision can mean life or death. But now, a new, low-cost study on the interactions of patients who are considered to be in a “minimally conscious state” (MCS) is showing a very exciting result that basic learning seems to take place in some individuals.

The type of learning is simple–the sort of classic conditioning demonstrated by Pavlov’s dog who salivated at the sound of a bell. Here, a tone is sounded followed by a light air puff to the eye. This is certainly an annoyance, so a conscious observer would tend to squeeze their eyelid shut to protect the pupil. After a short time of the repeated events, patients who physically responded to the air puff and who were seemingly unconscious demonstrated the same eyelid reaction after only the sounding of the tone.

The open question is to wonder if this sort of basic learning is so fundamental that true human consciousness is not required. So, Pavlov’s dog might be somewhat smart, but still not conscious. Or, if only a minimum level of consciousness is needed for basic learning (as the result of new, functional connections developing in the brain’s neural network), then a simple test of a successful Pavlovian response could be an important benchmark for determining the state of a patient who cannot communicate with the world. The hope would be that if simple learning is still possible, then further recovery and improvement in the brain’s responses could also be anticipated with additional therapies.

It’s certainly not a clear test of consciousness, but the approach is so simple and does not carry the enormous costs of brain imaging technologies. Therefore, essentially any hospital with low-conscious patients can perform this sort of experiment, which can further develop our weak understanding of human consciousness, and to improve the successful predictions required by doctors when dealing with patients on the verge of life or unconscious death.

“Conditional Consciousness: Patients in Vegetative States Can Learn, Predicting Recovery” :: Scientific American :: September 20, 2009 :: [ READ ]

Read more about MCS by Dr. Douglas I. Katz from [ READ ]


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Last updated February 16, 2018