Food storing, memory and the avian hippocampus

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Food-storing birds are important models in the study of animal behaviour and cognition. Their ability to remember the locations of large numbers of food caches has led to new discoveries about memory. Food-storing birds also have a larger hippocampus and greater recruitment of new neurons into the hippocampus than non-storing species. These specializations have made it possible to test novel ideas about memory and adult neurogenesis in animals in which memory plays a key role in their natural lives. Despite remarkable progress in research on these birds, we know surprisingly little about food-storing behaviour in nature and many questions remain about memory and the brain of food-storing birds. This proposal describes projects on 1) food storing behaviour in the wild, 2) cognitive control of memory, and 3) hippocampal neurogenesis in food-storing birds. Food storing by black-capped chickadees occurs in a social context. In fall and winter, when most storing occurs, chickadees live in flocks of up to 12 individuals. By attaching nanotag radio-transmitters to chickadees and erecting permanent radio antennas in chickadee habitat we have been able to obtain detections of many birds simultaneously and continuously for several months. In proposed research, radio-tag detection data will be combined with direct observation of caching behaviour to establish how individuals distribute and retrieve their caches within the constraints of group movement in the defended winter territory. Memory consists of multiple dissociable systems involving different brain regions. But the degree to which these processes operate independently is the subject of much debate and empirical research. Food storing and retrieval by black-capped chickadees occurs in the context of other behaviour. Because of their specialization for food caching, chickadees might be expected to have greater cognitive control of memory compared to non-caching birds. I propose to compare the cognitive control of memory in food-storing chickadees and non-storing dark-eyed juncos. Adult hippocampal neurogenesis is an enduring mystery. It has been hypothesized to both provide new neurons for new memories and to accelerate forgetting.  In chickadees, hippocampal neurogenesis is elevated in fall and winter in a pattern that corresponds roughly to elevated seasonal food storing. Despite tantalizing findings from my lab and others, however, there is little systematic research on the time course of adult hippocampal neurogenesis in birds or how new neurons integrate into hippocampal circuits. I propose to establish the time course of hippocampal recruitment, patterns of activity of new neurons (determined by immediate early gene expression) and the influence of using memory on neurogenesis in food-storing birds. This research will provide new information on cognition in the wild, the organization of memory, and the function of adult hippocampal neurogenesis.