Sagittal knife cuts in the near and far lateral preoptic area-hypothalamus disrupt maternal behaviour in female hamsters.

Parasagittal knife cuts with a varied mediolateral position were placed along the medial preoptic-medial anterior hypothalamic continuum (MPOA-MAH) in female hamsters. Near lateral (NL) knife cuts severed mediolateral connections between the MPOA-MAH and the medial forebrain bundle (MFB) while far lateral cuts (FL) were placed more laterally, sparing MPOA-MAH connections with the MFB. Across the knife cut condition, hamsters were either allowed to construct and maintain a food hoard or allowed to feed ad lib but not permitted to hoard. Animals were then tested for maternal behaviours. Both NL and FL cuts disrupted pup-directed behaviours in virgin maternal tests. NL, but not FL cuts severely disrupted nest building. These same animals were then mated and tested for maternal behaviour with their own young. There were no differences among the experimental groups in various maternal behaviours during these tests. Throughout lactation, however, the majority of NL and FL hamsters not permitted to hoard progressively cannibalized their entire litters. NL and FL counterparts with the hoarding opportunity, on the other hand, cannibalized fewer pups and reared healthy, moderate-sized litters that were smaller than those of surgical controls. That FL cuts were just as effective as NL cuts in disrupting pup-directed behaviour suggests that the mediolateral connections of the MPOA-MAH, other than with the MFB, are important for these behaviours.