Cryonics
The Brain Preservation Foundation’s (BPF) Small Mammal Prize has officially been won. A team has discovered a way to preserve the delicate neural circuits of an intact rabbit brain for extremely long-term storage using a combination of chemical fixation and cryogenic cooling. The prize represents an important prerequisite milestone towards the development of a robust memory preservation protocol for humans.
Over the last two decades cryonics researchers have made progress eliminating problems like ice formation in frozen tisssue using a technology from mainstream cryobiology called vitrification.
Vitrification uses high concentrations of cryoprotectants that allow tissue to solidify during cooling without the formation of ice crystals. When optimally applied, vitrification eliminates damage to cell structures caused by ice formation and has been shown compatible with recovery of biological functioning in small slices of isolated brain tissue.
However, when applied to whole brains, limitations in diffusibility lead to dramatic shrinkage of the brain’s tissue. Electron microscope images of such brains show dramatic distortions to the delicate neural circuits, and recovery of biological function in whole brains or animals remains far out of reach.
Such difficulties have led a new generation of researchers to focus on a more achievable and demonstrable goal –preservation of brain structure only, without concern for later biological viability. They focus on demonstrating preservation of the delicate pattern of synaptic connections, or the connectome, which neuroscience contends encodes a person’s memory and identity. Instead of biological revival, these new researchers often envision a future “synthetic revival” comprising nanometer-scale scanning of the preserved brain to serve as the basis for mind uploading.
Now a team from 21st Century Medicine, spearheaded by recent MIT graduate Robert McIntyre, has discovered a way to preserve the delicate neural circuits of an intact rabbit brain for extremely longterm storage using a combination of chemical fixation and cryogenic cooling.
Proof of this accomplishment, and the full “Aldehyde Stabilized Cryopreservation” protocol, was recently published in the journal Cryobiology and has been independently verified by the Brain Preservation Foundation through extensive electron microscopic examination. This answers a challenge issued to the scientific and cryonics communities five years ago by the BPF, and carries an award of $26,735.
"Every neuron and synapse looks beautifully preserved across the entire brain. Simply amazing given that I held in my hand this very same brain when it was vitrified glassy solid… This is not your father’s cryonics."
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The procedure included the live rabbit’s carotid arteries being perfused with glutaraldehyde and subsequent perfusion with cryoprotectant agent (CPA). Hayworth witnessed this rabbit brain being put in -135oC storage, removal from storage the following day (verifying that it had vitrified solid), and witnessed all subsequent tissue processing steps involved in the evaluation process.“Every neuron and synapse looks beautifully preserved across the entire brain. Simply amazing given that I held in my hand this very same brain when it was vitrified glassy solid… This is not your father’s cryonics,” stated Hayworth.
The winning team is focused now on the final Large Mammal phase of the contest which requires an intact pig brain to be preserved with similar fidelity in a manner that could be directly adapted to terminal patients in a hospital setting. The 21st Century Medicine team has recently submitted to the BPF such a preserved pig brain for official evaluation. Lead researcher Robert McIntyre has started a company, Nectome to further develop this method.
This result directly answers a main skeptical and scientific criticism against cryonics –that it does not provably preserve the delicate synaptic circuitry of the brain. As such, this research sets the stage for renewed interest within the scientific community, and offers a potential challenge to medical researchers to develop a human surgical procedure based on these successful animal experiments.
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