The tagging and capture hypothesis from synapse to memory

Abstract

Abstract The synaptic tagging and capture theory (STC) was postulated by Frey and Morris in 1997 and provided a strong framework to explain how to achieve synaptic specificity and persistence of electrophysiological-induced plasticity changes. Ten years later, the same argument was applied on learning and memory models to explain the formation of long-term memories, resulting in the behavioral tagging hypothesis (BT). These hypotheses are able to explain how a weak event that induces transient changes in the brain can establish long-lasting phenomena through a tagging and capture process. In this framework, it was postulated that the weak event sets a tag that captures plasticity related products (PRPs) synthesized by an independent strong event. The tagging and capture processes exhibit symmetry and therefore PRPs can be captured either if they are synthesized before or after the setting of the tag. In summary, the hypothesis provides a wide framework that gives a solid explanation of how lasting changes occur and how the interaction between different events leads to promotion, reinforcement or impairment of such changes. In this chapter we will summarize the postulates of STC hypothesis, the common features between synaptic plasticity and memory, as well as a detailed compilation of the findings supporting the existence of BT process. At the end, we pose some questions related to BT mechanism and LTM formation, which probably will be answered in the near future.