Measuring crab´s memory: improving conditioning

ANDINA ML; KLAPPENBACH M; LOCATELLI F; PEDREIRA ME; ROMANO A; FELD M

Huerta Grande, Córdoba

Congreso; Congreso de la Sociedad Argentina de Investigaciones en Neurociencias; 2013

Sociedad Argentina de Investigaciones en Neurociencias

Context-Signal Memory (CSM) of the crab Neohelice granulata has been exhaustively studied as a learning and memory model that allowed to unveil details from processes such as consolidation; reconsolidation; extinction and retrieval, among others. However, a limiting aspect of the experimental design has been that a lot of animals are needed to draw conclusions from results. Although initially interpreted as habituation, some characteristics of contextual conditioning have been described, but no anticipatory response had been detected for animals exposed to the training context.In the last few years we´ve been working in the development of a device to measure the crab´s escape response in such a way that allows lowering the number of individuals involved in experiments. For this purpose, the crab is hold from the dorsal carapace, over a cylinder that turns as the animal tries to move. A computer records distance and time, as controls a black rectangle that passes overhead in an angle of 90° (visual danger stimulus, VDS).Using the traditional device, it has recently been shown that discrete presentations of the context (conditioned stimulus, CS) that finish together with the VDS (unconditioned stimulus, US) increases the predictive nature of the CS, and an association-dependent anticipatory response is achieved. This new paradigm coined the name of Contextual Pavlovian Conditioning of the crab (crabCPC) (Fustiñana et al., 2012). In crabCPC, as in CSM, 15 training trials induce a robust freezing response and clear retention after short (2 and 4 h) and long (1?4 days) term US presentation. Also as CSM, crabCPC memory is context-specific and protein synthesis dependent; a weak CPC memory can be enhanced during consolidation and can be extinguished by repeated CS presentation 1 day after training. But, unlike CSM, crab CPC shows an anticipatory conditioned response (CR) during the CS presentation at short (4 h) and long (24 h) delays.Our challenge was to adapt crabCPC, developed using large numbers of animals, to the new device, developed for smaller numbers of individuals. Here, we show preliminary data showing mnesic retention might be achieved by the use of this device. This tool promises a whole new set of possibilities to venture into learning and memory mechanisms.