LAUSR

HighlightsThe ventral hippocampus possesses a left–right functional asymmetry in rats.The contribution of each hemisphere depends on the level of aversiveness.Both the left and right VH are activated during weaker anxiety.Only the right VH is activated during stronger anxiety. Abstract Many studies suggest that animals exhibit lateralized behaviors during aversive situations, and almost all animals exhibit right hemisphere‐dominant behaviors associated with fear or anxiety. However, which brain structure in each hemisphere underlies such lateralized function is unclear. In this study, we focused on the hippocampus and investigated the effects of bilateral and unilateral lesions of the ventral hippocampus (VH) on anxiety‐like behavior using the successive alleys test. We also examined the expression of c‐fos in the VH, which was induced by an aversive situation. Results revealed that consistent right VH dominance trended with the anxiety level. Weaker anxiety induced both right and left VH functions, whereas stronger anxiety induced right VH function. From these results, we conclude that animals are able to adaptively regulate their behaviors to avoid aversive stimuli by changing the functional dominance of their left and right VH.