From Synaptic Plasticity and Critical Periods to Social Behavior and Stress: Getting to, and Staying in, CA2

Hippocampal Area CA2, with some exceptions, had long been neglected in in vivo studies, due largely to its small size, and in in vitro studies because of its general similarity to CA3 and CA1. Increasing evidence showing that CA2 was molecularly distinct led to the increased appreciation of CA2 as a separate region, and as such, that it likely had functions that were dissimilar from its neighboring CA subfields that were worth studying. Indeed, it was the molecules that are enriched in CA2 that provided inspiration for many of the functional studies. In this article, I provide a personal account of how I got interested in CA2 and describe how I viewed our discoveries in the context of the others in the field. As it happened, much of my earlier work on synaptic plasticity in hippocampus and visual cortex had everything to do with why I felt compelled to ask the question, "are CA2 synapses resistant to long-term potentiation?." In fact, we are a product of our training and our environment when we are considering research directions.