05 January 2009

Watching While You Think and Learn

"With this method we can understand, in greater detail, how the human brain regulates complex thought processes and, for example, how it transforms the numerous sensory impressions into long-term memories" _MNT
The circuits of your brain trace complex paths across space and time. Understanding how brains think means understanding the spatial and temporal actions of the neuronal correlates of thought. Nature Methods has a recent (4Jan09) online report describing the use of a trio of genetically engineered viruses used to trace the activity of complex brain circuits.
In a recent paper in Nature Methods, the team describes the production and application of three types of transsynaptic viruses. The first class was engineered with differentially colored “bulbs” such that neural circuits can be lit up with all the colors of the rainbow. The second type of virus brings a small genetic clock into each infected cell in the circuit so that the elapsed time after virus entry can be recorded. The third class has the most intelligent nanotools. These viruses turn on a special fluorescent bulb in each neuron but only when the neuron is active. Using these tools, researchers can now “watch” the activity of many neurons simultaneously in identified, connected neurons of different brain circuits. _FMI
This work extends previous work using engineered viruses to act as trans-synaptic "ferries" of genes encoding for fluorescent proteins, to infect specific neurons along the path of a particular brain circuit. Such infected neurons along the circuit will subsequently "light up" like a light bulb when activated.
The protein complex was actually produced in the nerve cells of the "infected" mice and functions there as an calcium indicator: if the calcium level within a cell increases - which is the case with every action potential - the D3cpv changes form when it binds to calcium. As a result, the two fluorescent proteins, CFP and YFP, move closer to each other and the transmission of energy between the CFP and YFP changes.

"To observe this change, we use a two-photon microscope developed by Winfried Denk", explains Hasan. Each individual action potential that arises due to a stimulus makes itself directly perceivable in the brain through yellow illumination and the simultaneous reduction in the emission of blue light. The two-photon microscope pinpoints the coincidence between the two fluorescent signals very accurately and clearly reveals which nerve cells are communicating and exchanging information with each other and when. _MedNewsToday
Such methods of observing functioning brain circuits over a period of time should help in piecing together how the brain "thinks." Other tools such as special types of fMRI, MEG, nuclear medicine techniques such as PET and SPECT, etc. will further complete the overall picture, when correlated with psycho-neurological observations.

A reliable "lie-detector" would be a simple test of concept. As expertise with these methods of real-time brain tracing improves, a more subtle and sophisticated reading of minds will become possible.

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Blogger Snake Oil Baron said...

Next year I am decorating a Christmas tree with these mouse brains. I have always wanted an excuse to do that.

Granted, few of my guests will be interested in using a two photon microscope to get the full yuletide effect but then I probably won't have many guests with a Christmas tree covered in mouse brains in my living room.

It is plausible that some of the information gathered from this technique used on animals could dovetail into some of the other (non virus using) technologies you mentioned for human medical advances and AI research. The motor skills and general problem solving abilities of a mouse are nothing to sneeze at when designing droid armies and seeing eye Rombas.

Monday, 05 January, 2009  
Blogger al fin said...

Yes, Baron. If you add neural implants, DBS, neural language processing chips, and so on, the possibilities are immense.

As you say, it isn't necessary to achieve human intelligence levels or above in machines to create a formidable machine force.

Saturday, 17 January, 2009  

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“During times of universal deceit, telling the truth becomes a revolutionary act” _George Orwell

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