Anesthesia as a consciousness scalpel

I’ve just written a piece for the Discover Magazine blog The Crux about a new study that used anaesthetics to “put people under” and test the limits of their conscious mind even after they’d stopped responding to the outside world.

Doing psychology experiments on people undergoing anaesthesia is not a new idea but it has always been done on people who volunteered due to undergoing genuine surgery. But this was the first study to put volunteers under anaesthesia solely as part of an experiment.

In this case, the experiment tested whether people had conscious experiences despite being unable to respond to outside stimuli – the medical definition of being unconscious.

It turns out the conscious mind keeps working way past the point where people are medically defined as unconscious.

In addition to the standard surgical way of checking unconsciousness, participants were also regularly asked to open their eyes to check when they stopped and started responding. Afterwards, each participant was questioned about their memories of the anesthesia session to see if they had conscious experiences even when seeming to be comatose. These included simple thoughts or perceptual experiences like flashes of light, to more complex experiences such as seeing or hearing the researchers, or having dream-like, out-of-body hallucinations.

It turns out that despite being rated as unresponsive and, therefore, by the current medical definition, unconscious, participants reported conscious experiences in about 60% of the sessions. This does not mean that everyone was “awake” as we normally understand it, as the extent to which the experiences reflected the reality of what was going on around the person varied, but the volunteers were clearly having conscious experiences.

Excitingly, the researchers suggest that experimental anaesthesia could be used as a ‘dimmer switch’ for the mind to find the point where no further conscious experience takes place.

Doing these studies while studying brain activity could help us understand which brain circuits are needed for the cross-over into consciousness.

More at the link below.

Link to ‘Anesthesia May Leave Patients Conscious—and Finally Show Consciousness in the Brain’.

3 thoughts on “Anesthesia as a consciousness scalpel”

  1. Do these experiements control for accuracy of conscious perception, or it is possible that the reported experience was something they anticipated or imagined before going under — e.g., doctors talking in the room, etc.?

  2. Fascinating. I wonder about anesthetizing specific parts of the brain; for example, I know that left- or right-side anaesthesia, applied to the entire hemisphere, can interfere with facial recognition (and presumably a whole lot of other stuff)… it could be interesting to try to deliver pinpoint doses to various regions to test the effects, both in experience and communication.

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