Would you mind summarizing the summary? :) I’m not familiar with the science but would like to understand the gist of why the work of those two competitors is important.
Sure. Basically, there are two groups, each of which has made a major contribution:
1) Shawn Mikula and his group. They have made substantial progress (some would say, almost solved) of how to make the neuronal connections and other brain structures such as white matter tracts in a full mouse brain traceable using electron microscopy. Electron microscopy is the lowest level of imaging currently feasible, and can clearly resolve structures that are thought to be key to memory such as synapses.
2) The 21CM group, including Robert McIntyre. They have developed a totally new method of preserving a brain that should yield both highly practical and technical sound preservation. In a sense it combines the methods discussed by Gwern in his article Plastination vs Cryonics, because it first uses a method traditionally associated with “plastination” (glutaraldehyde perfusion), and then uses a method traditionally associated with cryonics, i.e. perfusion with a cryoprotective agent and then low temperature storage and, presumably, vitrification, which means that damage from ice crystal formation should be avoided and the brain should turn a glass state.
Apologies if this is still too technical and I’m happy to answer any follow-up questions. Many key steps remain but this is progress worthy of celebrating and, in my view, supporting.
it first uses a method traditionally associated with “plastination” (glutaraldehyde perfusion), and then uses a method traditionally associated with cryonics, i.e. perfusion with a cryoprotective agent and then low temperature storage and, presumably, vitrification, which means that damage from ice crystal formation should be avoided and the brain should turn a glass state.
No, I don’t think so; although I don’t know exactly what is in the 100 ul of “Equilibration Solution” and “Vitrification Solution”, I highly doubt that they cross-link any proteins like glutaraldehyde does. Because C. elegans are so small, it is much easier for standard cryoprotectant agents to diffuse across them. So, methods to stabilize blood vessels and tissue parenchyma prior to cryoprotectant agent perfusion, which is valuable in larger animals such as pigs, are not necessary in C. elegans.
As I understand it, the major advantage is that doing the cross-linking first (e.g. w glutaraldehyde) saves you time and maintains blood vessels so that traditional cryoprotectants can diffuse more widely across brain tissue. It also may allow easier validation of the cryopreservation protocol, because you don’t have as many dehydration issues.
Would you mind summarizing the summary? :) I’m not familiar with the science but would like to understand the gist of why the work of those two competitors is important.
Sure. Basically, there are two groups, each of which has made a major contribution:
1) Shawn Mikula and his group. They have made substantial progress (some would say, almost solved) of how to make the neuronal connections and other brain structures such as white matter tracts in a full mouse brain traceable using electron microscopy. Electron microscopy is the lowest level of imaging currently feasible, and can clearly resolve structures that are thought to be key to memory such as synapses.
2) The 21CM group, including Robert McIntyre. They have developed a totally new method of preserving a brain that should yield both highly practical and technical sound preservation. In a sense it combines the methods discussed by Gwern in his article Plastination vs Cryonics, because it first uses a method traditionally associated with “plastination” (glutaraldehyde perfusion), and then uses a method traditionally associated with cryonics, i.e. perfusion with a cryoprotective agent and then low temperature storage and, presumably, vitrification, which means that damage from ice crystal formation should be avoided and the brain should turn a glass state.
Apologies if this is still too technical and I’m happy to answer any follow-up questions. Many key steps remain but this is progress worthy of celebrating and, in my view, supporting.
Is this related to the new SafeSpeed process used in http://lesswrong.com/r/discussion/lw/m8g/link_persistence_of_longterm_memory_in_vitrified/ ?
No, I don’t think so; although I don’t know exactly what is in the 100 ul of “Equilibration Solution” and “Vitrification Solution”, I highly doubt that they cross-link any proteins like glutaraldehyde does. Because C. elegans are so small, it is much easier for standard cryoprotectant agents to diffuse across them. So, methods to stabilize blood vessels and tissue parenchyma prior to cryoprotectant agent perfusion, which is valuable in larger animals such as pigs, are not necessary in C. elegans.
What are the advantages to the hybrid approach as compared to traditional cryonics? Histological preservation? Thermal cracking? Toxicity?
As I understand it, the major advantage is that doing the cross-linking first (e.g. w glutaraldehyde) saves you time and maintains blood vessels so that traditional cryoprotectants can diffuse more widely across brain tissue. It also may allow easier validation of the cryopreservation protocol, because you don’t have as many dehydration issues.