Long-term memory induced by two training trials in the crab Neohelice granulata

OJEA RAMOS S; ANDINA ML; FELD M

Berlin

Simposio; FENS forum; 2018

Federation of European neuroscience Societies

Historically, context-specific long term memory (LTM) in the crab Neohelice granulata was disclosed 24h after 15 training trials using aversive stimuli presentation with an intertrial interval (ITI) of 3min. Furthermore, Neohelice LTM has been extensively studied at different levels (e.g. behavioural, pharmacological, molecular and electrophysiological). Based on previous studies in Aplysia, we designed a new training protocol of 2-trials (ITI: 45min) that allows LTM expression 24h afterwards (2t-LTM). We found that 2t-LTM is dependent on the ITI (45 min, but not 3 or 60 min, allow 24h-memory formation), expresses context-specificity and sensitivity to protein synthesis inhibitors both during consolidation and reconsolidation. Moreover, a MEK-1 (extracellular signal-regulated kinase 1/2, ERK1/2, kinase) inhibitor administered between both training trials selectively impaired 2t-LTM when given 15 or 22.5 min after the first one. The underlying hypothesis is that the first trial induces a specific molecular context in the neurons involved in the trace, mediated by the activation of the ERK/MAPK pathway. Upon second trial presentation, LTM formation is triggered specifically in the 45min-ITI condition. Here, we show that 2t-LTM parametrically resembles other conditioning protocols and represents an attractive model for studying individual trial input and ITI contribution to the activation of putative molecular pathways involved in memory formation.