Navigational memories in ants and bees: Memory retrieval when selecting and following routes

Ants and bees have an impressively rich store of navigational memories that are linked together in complex ways. We have stressed that to accompany their large store of memories, insects need adequate mechanisms that allow the appropriate memories to be retrieved reliably. One way that insects, like other animals, seem to reduce possible retrieval errors is by linking together the different parts of a memory and by associating a memory with its own spatial and temporal context. That way memories are primed by the correct combination of cues; a flexible many-pronged key to unlock the appropriate memory that only works if most of the prongs find their proper slot. These learnt cues are encountered as an insect travels along a route through familiar terrain. Route following gives a significant sequential component to memory retrieval such that a cue experienced at one moment can contribute to priming a memory a short while later. A second part to memory retrieval is choosing memories appropriate to a particular route. This process is somewhat like picking out the right collection of keys. It is uncertain whether memories of a route are handily bunched together on their own ring and can be addressed as a group, or whether memories are fingered individually. That insects prime the memories that belong to a particular route, while ignoring those that are irrelevant, is one more reason for supposing that visual, navigational memories serve fixed routes (Collett et al., 2003; Dyer, 1991; Wehner and Menzel, 1990; Wehner et al., 1996, 2006) rather than being organized in a graph-like structure that could mediate the planning of novel routes (Gould, 1986; Menzel et al., 2005). © 2006 Elsevier Inc. All rights reserved.