Researchers in Sheena Josselyn's lab report that a memory trace for a fearful experience can be selectively deleted in mice. Are we on the verge of localizing specific memories in the brain?
The full article can be found in JH Han et al. (2009) "Selective erasure of a fear memory." 323(5920): 1492-6. Here is the abstract:
Memories are thought to be encoded by sparsely distributed groups of neurons. However, identifying the precise neurons supporting a given memory (the memory trace) has been a long-standing challenge. We have shown previously that lateral amygdala (LA) neurons with increased cyclic adenosine monophosphate response element-binding protein (CREB) are preferentially activated by fear memory expression, which suggests that they are selectively recruited into the memory trace. We used an inducible diptheria-toxin strategy to specifically ablate these neurons. Selectively deleting neurons overexpressing CREB (but not a similar portion of random LA neurons) after learning blocked expression of that fear memory. The resulting memory loss was robust and persistent, which suggests that the memory was permanently erase. These results established a causal link between a specific neuronal subpopulation and memory expression, thereby identifying critical neurons within the memory trace.