D. student who did the experiments. But when we mated the mutants, we found that both parents neglected their offspring. The mothers left the pups scattered around the cage, and did not nurse them. When we placed some of the pups with normal mothers, they did fine. That doesn't mean one gene determines one type of behavior, nature directly driving nurture.
Biology is much more complex.
FosB then turns on other genes, and the end result is an adaptive response to a change in an animal's surroundings. Greenberg strives to discover which genes get involved in which behaviors. He wants to know exactly how they work, not in general terms, but on a molecule by molecule level. For example, researchers know certain factors can activate genes in brain cells in a way that contributes to the cells' degeneration. Since aging also is associated with degeneration of brain cells, it may even be feasible to selectively enhance the survival of cells involved in learning, memory, and other cognitive functions that deteriorate with age.