Dynamics of the formation of new associations during memory consolidation in Chasmagnathus granulatus

LUIS DANIEL SUÁREZ; LETICIA SMAL; ALEJANDRO DELORENZI

Huerta Grande, Córdoba

Taller; X Taller Argentino de Neurociencias; 2008

Taller Argentino de Neurociencias

In the Context-Signal Memory (CSM) model in Chasmagnathus, a Visual Danger Stimulus (VDS) is associated with the training context. As a result of a strong training protocol (STP), MCS is expressed at least for five days. A single presentation of the VDS, usually insufficient for building a long-term expression CSM, can generate it if it happens inside a time coincident with MCS consolidation. This time also coincides with short-term memory expression which, at difference of long-term expression, is context-independent.             This work explores whether what Chasmagnathus have learned from a single presentation of the VDS, after a STP in a different context, leads to the formation of a new memory or whether it is a modification of the original memory produced by the STP. For this, we have evaluated if a consolidation process, defined in terms of protein synthesis requirement, is necessary for this new learning, after the STP or after the single presentation of the VDS in the second, different context. We also have evaluated whether long-term expression of the MCS in the second training context is due to new association learning or whether it is due to a process of generalization, i.e.: a loss in context discrimination. Finally, using reconsolidation as a tool, we have studied whether reactivation of what was learned in one context produces reactivation of the information acquired in the other context.             Our results show that for hours after a STP, a single presentation of the VDS in a different context is enough to generate a new association, which requires protein synthesis after this single presentation, but not after the initial STP. The unreinforced presentation of any of the two training contexts triggers labilization of the association learned in that context, but not the one learned in the other training context. We concluded that this behavioral re-arranged process is not a modification of the original memory as it has been originally proposed. We propose that two different memory traces are involved in the formation of these memories.