Left–right dissociation of hippocampal memory processes in mice

Significance The hippocampus is implicated in memory and spatial navigation. In rodents, in which this bilateral brain structure has been studied extensively, the left and right hippocampi have generally been considered functionally equivalent. However, recent work has revealed unexpected asymmetries in the molecular and morphological characteristics of neuronal connections according to brain hemisphere. To investigate whether this left–right difference has implications for hippocampal function, we acutely inhibited activity in an area-specific and genetically-defined population of hippocampal neurons during various behavioral tasks. We found that silencing the CA3 area of the left hippocampus impaired associative spatial long-term memory, whereas the equivalent manipulation in the right hippocampus did not. Thus, our data show that hippocampal long-term memory processing is lateralized in mice.