Dorsomedial forebrain ablations and home loft association behavior in homing pigeons

In a series of experiments which involved only short distance experimental releases (800 m or less and within view of the home loft), it was demonstrated that dorsomedial forebrain ablated pigeons generally failed to reassociate with their home loft if the postablation experimental release took place soon postablation or if during the time between ablation and experimental release they were kept away from their home loft. In contrast, if dorsomedial forebrain ablated pigeons were allowed to recover at their home loft prior to experimental release, they succeeded in associating with their home loft in a manner similar to controls. However, only postablation exposure to a pigeon's own loft was sufficient to permit continued home loft association. Pigeons from one loft failed to associate with a foreign postablation recovery loft when released within sight of it. The results show that dorsomedial forebrain ablations result in pigeons which no longer succeed in associating with their home loft; recovery from failed home loft association behavior is possible with postablation exposure to the home loft, and a pigeon's previous association with a loft was a precondition if postablation association was to be affected. The results suggest that dorsomedial forebrain ablated pigeons retain something like a 'home loft trace' which they can use to mediate retrieval and reformation of the recognition properties needed for proper home loft association.