Ever heard that “you’re born with all the brain cells you’ll
ever have”? It turns out that could be a good thing – if it were
true. A new study shows that at least in some circumstances,
neurogenesis actually impairs memory performance. To understand
why this might be the case, consider that adults are constantly
generating new neurons in a long-term memory structure – the
hippocampus. This region requires a large number of neurons to
store episodic memories accumulated over a lifetime (and
understandably so!). Similarly, to be able to store experiences
that may have occurred very quickly, neurons in the hippocampus
learn very fast. Finally, to reduce interference from other
similar memories, neural activity there is very sparse and
highly non-overlapping (so that the hippocampus doesn’t
accidentally confuse two similar experiences). These
characteristics make this region particularly useful for quickly
learning relationships between stimuli. Accordingly, damage to
the hippocampus, and disruption of neurogene