THE SPACING EFFECT: INVESTIGATION ABOUT THE NEUROBIOLOGICAL BASIS OF DISTRIBUTED LEARNING PARADIGMS

A common hallmark of many types of learning is that information presented using spaced repetitions is better remembered than information presented via massed repetitions. Although this phenomenon has long been known only recently insight from molecular studies provide evidence relative to its possible substrate. On the contrary, still unexplored are the mechanisms that contribute to better stability of distributed learning as compared with massed learning at a cellular and network level. To this purpose we compared in the Morris water maze (MWM) the effect of six training sessions distributed over three days with that of training massed in a single day. CD1 mice trained with the two training protocols did not differ in the ability to locate the platform 24hrs after the last training session. However, when tested 14 day after training, only the spaced-trained mice could efficiently remember the platform location. Analysis of learning did not reveal did any difference in the learning curve or in the strategy used to acquire the task in the two experimental groups. To explore the possibility that distributed compared to massed spatial training in the MWM might involve alternative network we are now investigating the effects of AMPA receptor blockade in the different component of the striatal complex on memory retrieval. Our results demonstrate that AMPA receptor activity in the dorso-medial but not the dorso-lateral striatum is required for retrieval of spatial information acquired with massed training. We are currently investigating the role of AMPA receptors in the same structures in recall spatial information learned with a spaced protocol.