FINDING A MECHANISM SUBSERVING EXTINCTION

DE LA FUENTE V; ROMANO A

Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Bahía Blanca, Argentina.

Workshop; ?Neuronal Communication: From structure to physiology?; 2008

Sociedad Argentina de Investigación en Neurociencias (SAN)

Two main hypothesis intend to explain memory extinction. The first one implies an inhibition pathway that inhibits the original trace of memory. It is proposed that to be established, extinction memory needs mechanisms similar at the ones involved in consolidation of the original memory. The other hypothesis, implies a weakening of the original trace, so it is thought that opposite mechanisms implied in consolidation of the original memory, are needed (for example, phosphorilation and dephosphorylation). Both hypotheses are not mutually exclusive. We have already observed, in a paradigm of fear conditioning, that fifteen minutes after a re-exposure which normally subserves reconsolidation, there?s an increase of the activity of the transcription factor NF-kB, and that this activity is necessary for reconsolidation to be held. This increment in the activity is not seen during or after a prolonged re-exposure of 30 min that leads to extinction. On the other hand, many studies suggest that Calcineurin phosphatase is involved in extinction. Considering that NF-kB has a phosphorilation site for PKA, which increases its activity; and that NF-kB is also activated by IkB (NF-kB inhibitor) phosphorilation, we wanted to know whether there?s any relationship between both NF-KB and Calcineurin phosphatase during extinction, and whether this relationship accounts for Calcineurin participation in this memory phase. Up to now we observed no changes in Calcineurin protein levels after protocols that lead to reconsolidation or extinction.