Behavioral Tagging: the synaptic tagging hypothesis translated into behavior and its contribution to the study of long-term memory formation

MONCADA, DIEGO

Barcelona

Congreso; FENS forum 2012; 2012

FENS

Oral presentation in Session 03: From synapses to behavior, the synaptic tagging and capture hypothesis in memory maintenance. Consolidation of long-term memories (LTM) requires the synthesis of plasticity-related proteins (PRPs). This synthesis is generally triggered by a proper salient experience (strong event) that will be finally remembered. However, we have recently shown that a week learning, which normally results in transient forms of memory, can also use PRPs provided by another strong associated event in order to stabilize its mnemonic trace into LTM. This revealed the existence of a ´Behavioral Tagging´ (BT) process (resembling the ´Synaptic Tagging´ (ST) process described in long-term potentiation -LTP-), based on both the setting of a ´learning-tag´ and the synthesis of PRPs. Here we provide a brief description of how the fundaments and properties of the ST theory can be translated into behavior, showing the generality of the BT process across different kinds of memories, processed in different brain areas. Then, using the Open-Field induced Inhibitory Avoidance (IA)-LTM ´BT-model´, which allows the dissection of the tagging and PRPs synthesis processes, we demonstrate that hippocampal D1/D5-dopaminergic and ß-adrenergic receptors are essential to induce the synthesis of PRPs required for memory consolidation; while in addition NMDA receptors are necessary for the setting of the IA-learning tag, which machinery also involves CAMKIIa and PKA. Providing strong evidence that the modulator effect of these chatecolaminergic systems is due to their involvement in the synthesis of PRPs, which is required to such extent that makes them essential for LTM formation. Finally we use BT experiments to study the effects of electrophysiological stimulation on memory formation, and demonstrate that tetanic stimulation, able to produce LTP in the hippocampus, promotes the formation of different hippocampus-dependant LTMs in rats. In summary we outline the latest advances resulted of applying the ST theory to animal behavior, and the advantages of using BT protocols to study learning and memory processes.