Sweet Revenge?

20 to 30 minutes to reach a stable state. What do these findings suggest about spatial processing within the hippocampus? One possibility is that CA3 encodes the animal's location with reference to the current environmental context. This would be a useful extension to the coding scheme in the entorhi-nal cortex, where " place cells " appear to be relatively immune to changes in the environment (8). The context-dependent representation in CA3 might allow spatial memory to differentiate between different environments and so, for example, allow me to locate my car in the supermarket parking lot without interference from occasions when I parked it at the mall. But what about CA1? Leutgeb et al.'s finding that the pattern of activity in CA3 can change without affecting CA1 activity suggests that the CA1 region responds to direct inputs from the entorhinal cortex rather than to information routed through CA3 (9, 10). But why would CA1 echo the entorhinal representation? One possibility is that CA1 melds information that was not explicitly examined by Leutgeb et al. into the spatial representation. Such information could include nongeometric features of the environment, such as odor or behavioral contingencies, or internal states such as hunger, thirst, or motivation. Alternatively, because remapping is known to take place in this region following manipulations of the spatial relationship between local and distal cues (10), CA1 may help to represent intercue associations. With these questions still waiting to be answered, it will be interesting to see how future studies gradually tease apart the components of the entorhinal-hippocampal memory system. This process will lead to a clearer picture of how neural networks in these regions interact during memory storage and retrieval. Now, where did I leave my keys? Y ou've been waiting in line in traffic for what seems like hours, when a red sports car whips past on the shoulder. Eventually, the sports car creeps back into view—the driver has run out of shoulder and signals to be let in. Instead of giving way, you stare ahead and accelerate, inching dangerously close to the bumper in front of you. After squeezing back the intruder , you can't help but notice a smile creep onto your face. Judges worry, whereas filmmakers delight , in the fact that revenge feels good. Evolutionary theorists argue that such an " eye-for-an-eye " strategy makes sense, preventing future damage to one's self or kin (1, 2). …