Figure 2.

Injecting the viral construct. (A) Injecting system: First, the guide-tube (g) is inserted into one of the grid holes. A spacer (s) prevents the guide-tube from descending under the surface of the grid. Then, the injector (i) is lowered into the brain through the guide-tube until it reaches the target (1 mm above the LC). It is held in place by the needle holder and connected (c) to the flexible tubing (t). (B) During an injection: The two manipulators are mounted on the stereotaxic frame, one holding the Hamilton syringe (left), the other holding the injecting system (right), both connected to each other by the flexible tubing. Here, the injector is already in position in the brain.