Multiple theories and models of consciousness have been proposed, and experts tussle back and forth about which is most accurate. Some critics even claim that most theories of consciousness are “worse than wrong” — they don’t actually explain anything.
Physiologically, the EEG is still the most sensitive measure to indicate consciousness. When an individual is awake and alert, the EEG is “activated,” characterized by low voltage, high frequency fast brain waves.
When there is a loss of consciousness, brain waves slow down and get higher in amplitude as brain cells alter their firing rates.
Parts of the brain thought to be involved in consciousness include the rear part of the cerebral cortex (at the surface), and also deeper structures such as the brainstem. EEG activity in specific areas of the brain may be one of the most effective ways to discriminate between conscious and unconscious individuals.
Can A Brain Without A Body Be Conscious?
Currently we are a long way from experimental models of the human brain — such as brain organoids or disembodied brains — being conscious. However, we could need to confront such a possibility as technology advances and models become more sophisticated.
Indeed, the hope of this has led to initiatives such as cryogenically preserving (freezing) brains, and even proposed head transplants.
But I wouldn’t rush out and put my name down for these procedures just yet. In the case of cryogenically preserving tissue, evidence has yet to demonstrate that all areas of the brain are reached with the antifreeze used to protect tissue from fracturing at the extremely low temperatures.
Even if the tissue can somehow be protected from freezing damage, warming that tissue back up again is likely to result in further extensive problems. This would make it difficult, if not impossible, to ever return the brain to a conscious state — and that’s all before you deal with the issues inherent in actually transplanting the brain into another body.
Many unknowns also exist with head transplants. While Italian neurosurgeon Professor Sergio Canavero has claimed that he will carry out the first human head transplant in 2018, many neuroscientists are skeptical.
There are a host of issues with such a procedure. There’s the possibility of rejection of the head by the donor body, and the difficulty of connecting the spinal cord to the brain in a way that the brain can control the donor body. Additionally, even if it did work in a physical sense, there are problems around how such a procedure might affect the individual’s sense of self-awareness or consciousness.
Where Should the Field Go From Here?
There are many ethical concerns linked to the idea of brains in culture or removed from bodies – including what protections are necessary, how to address issues around consent, ownership, and post-research tissue handling, and even how to define death.
In late April, 17 experts in neuroscience, stem-cell biology, ethics, and philosophy published an editorial in Nature outlining many of the issues that need to be considered and calling for “clear guidelines for research”.
Such conversations also need to be held outside of academic circles and should engage ethics committees, research funding bodies, and, most importantly, the wider public.
While there has never been a more exciting time to work in neuroscience, it is critical that proper safeguards be put in place now as models continue to advance.
This article from Lyndsey Collins-Praino of the University of Adelaide was originally published at The Conversation.
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