In a similar vein, very deep anesthesia can lead to “burst suppression” where the brain becomes iso-electric. This is avoided in usual clinical or surgical practice, because there is no pragmatic benefit from going that far. In the elderly or unwell, it correlates to increased risk of post-operative delirium or transient cognitive impairment.
However, trials on healthy volunteers found no evidence of cognitive impairment or worsened recovery times.
>Volunteers demonstrated marked variability in multiple features of the suppressed EEG. In order to test the hypothesis that, for an individual subject, inclusion of features of suppression would improve accuracy of a model built to predict time of emergence, two types of models were constructed: one with a suppression-related feature included and one without. Contrary to our hypothesis, Akaike information criterion demonstrated that the addition of a suppression-related feature did not improve the ability of the model to predict time to emergence. Furthermore, the amounts of EEG suppression and decrements in cognitive task performance relative to pre-anaesthesia baseline were not significantly correlated.
Now, the brain and body was clearly on life support (as is necessary if you’re doing this with a warm body), but that’s another example of how the brain can bootstrap consciousness after severe disruption and signaling failure. Then there’s the evidence from people who endure generalized seizures (though those can cause damage because of excitotoxicity, my point is that disruption is not death or necessarily severe damage).
Or even ECT, which is the closest my profession gets to turning the whole system off and on again, and which works remarkably well.
It didn’t make the final draft of this post, but we did consider mentioning anesthesia’s ability to turn the brain ‘off’. I like Matta et al 1995, because “make the brain flatline on an EEG” was considered harmless enough by the medical community that it passed an ethics review board to do this to patients who didn’t need it, just because it helped researchers test the exact mechanisms of anesthetic operations:
In a similar vein, very deep anesthesia can lead to “burst suppression” where the brain becomes iso-electric. This is avoided in usual clinical or surgical practice, because there is no pragmatic benefit from going that far. In the elderly or unwell, it correlates to increased risk of post-operative delirium or transient cognitive impairment.
However, trials on healthy volunteers found no evidence of cognitive impairment or worsened recovery times.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6676227/
>Volunteers demonstrated marked variability in multiple features of the suppressed EEG. In order to test the hypothesis that, for an individual subject, inclusion of features of suppression would improve accuracy of a model built to predict time of emergence, two types of models were constructed: one with a suppression-related feature included and one without. Contrary to our hypothesis, Akaike information criterion demonstrated that the addition of a suppression-related feature did not improve the ability of the model to predict time to emergence. Furthermore, the amounts of EEG suppression and decrements in cognitive task performance relative to pre-anaesthesia baseline were not significantly correlated.
Now, the brain and body was clearly on life support (as is necessary if you’re doing this with a warm body), but that’s another example of how the brain can bootstrap consciousness after severe disruption and signaling failure. Then there’s the evidence from people who endure generalized seizures (though those can cause damage because of excitotoxicity, my point is that disruption is not death or necessarily severe damage).
Or even ECT, which is the closest my profession gets to turning the whole system off and on again, and which works remarkably well.
It didn’t make the final draft of this post, but we did consider mentioning anesthesia’s ability to turn the brain ‘off’. I like Matta et al 1995, because “make the brain flatline on an EEG” was considered harmless enough by the medical community that it passed an ethics review board to do this to patients who didn’t need it, just because it helped researchers test the exact mechanisms of anesthetic operations:
https://journals.lww.com/anesthesiology/fulltext/1995/11000/direct_cerebrovasodilatory_effects_of_halothane,.11.aspx