This technique takes a dead brain and permeates it with a transparent hydrogel matrix to keep proteins and nucleic acids in place. Then it removes the lipids. I guess the lipids are all that makes the brain opaque. At this point the brain is transparent but maintains its original structure so you can still label the proteins and nucleic acids.
Craig Venter has made a bacterium from an entirely synthesized genome (link is nice summary in WSJ). Here’s the paper in Science. Now, that that’s taken care of… who will be the first to design a “synthetic biological neural circuit”?
This has been done for quite awhile but I thought I’d post about it because I think it’s a neat idea — genetically manipulate experimental subjects so that only some cells have the mutation, while others are wild-type.
When we learn new information we use only a tiny fraction of the neurons in our brain for that particular memory trace. In order to allow the molecular study of those specific neurons we combined elements of the tet system with a promoter that is activated by high level neural activity (the cfos promoter) to generate mice in which a genetic tag can be introduced into neurons that are active at a given point in time. The tag can be maintained for a prolonged period, creating a precise record of the neural activity pattern at a specific point in time. Using fear conditioning we found that the same neurons activated during learning were reactivated when the animal recalled the fearful event. We also found that these neurons were no longer activated following memory extinction, consistent with the idea that extinction modifies a component of the original memory trace.