Shawn Mikula on Brain Preservation Protocols and Extensions

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Recently published article in Nature Methods on a new protocol for preserving mouse brains that allows the neurons to be traced across the entire brain, something that wasn't possible before. This is exciting because in as little as 3 years, the method could be extended to larger mammals (like humans), and pave the way for better neuroscience or even brain uploads. From the abstract:

Here we describe a preparation, BROPA (brain-wide reduced-osmium staining with pyrogallol-mediated amplification), that results in the preservation and staining of ultrastructural details throughout the brain at a resolution necessary for tracing neuronal processes and identifying synaptic contacts between them. Using serial block-face electron microscopy (SBEM), we tested human annotator ability to follow neural ‘wires’ reliably and over long distances as well as the ability to detect synaptic contacts. Our results suggest that the BROPA method can produce a preparation suitable for the reconstruction of neural circuits spanning an entire mouse brain

http://blog.brainpreservation.org/2015/04/27/shawn-mikula-on-brain-preservation-protocols/

Here we describe a preparation, BROPA (brain-wide reduced-osmium staining with pyrogallol-mediated amplification), that results in the preservation and staining of ultrastructural details throughout the brain at a resolution necessary for tracing neuronal processes and identifying synaptic contacts between them. Using serial block-face electron microscopy (SBEM), we tested human annotator ability to follow neural ‘wires’ reliably and over long distances as well as the ability to detect synaptic contacts. Our results suggest that the BROPA method can produce a preparation suitable for the reconstruction of neural circuits spanning an entire mouse brain

http://blog.brainpreservation.org/2015/04/27/shawn-mikula-on-brain-preservation-protocols/

Neurons perform analog summation, so the space-time diagram or causal structure is stochastic/statistical rather than deterministic

Surely you realize that quibbling over the use of analog vs digital neural summation in my toy example does not address my main argument.

Neural analog computational systems can be simulated perfectly in a probabilistic sense

Anything can be simulated perfectly (and trivially) in a probabilistic sense.

There are no objective tests for consciousness. Of course you can re-define it in terms of self-awareness but this is not the same.

A definition of consciousness which precludes objective testing is outside the realm of scientific inquiry at best, and pseudo-science at worse.

If we knew the basis for consciousness, we would have objective tests. It's possible that studying the brain's structural and connectional organization in detail will provide the clues we need to develop better informed opinions about the basis of consciousness.

This is my final post and I would like to thank everyone for the discussion. If anyone is interested in developing autotracing and autosegmentation programs for connectomics and neural circuit reconstruction in whole-brain volume electron microscopy datasets, please email me at brainmaps at gmail dot com or visit http://connectomes.org for more information. Thanks again.

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Shawn Mikula on Brain Preservation Protocols and Extensions

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Shawn Mikula on Brain Preservation Protocols and Extensions

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