Processing of visual information by spatial memory circuits in the avian brain

PROJECT SUMMARY / ABSTRACT. Research Project: Spatial memory – memory of where an event happened or an object was located – depends on the hippocampus in a wide range of vertebrate species, including mammals and birds. In humans, most spatial memories are formed through visual experience. However, it is unclear how visual information is processed by hippocampal memory circuits to support spatial memory formation. Two obstacles have hindered answering this question: 1) the complexity of networks in which the hippocampus is embedded in mammals, and 2) the need to observe many independent memories being formed and recalled at identifiable moments in time. This project overcomes these obstacles by leveraging the unique advantages of the black-capped chickadee Poecile atricapillus, a food-caching bird that depends on an intact hippocampus to retrieve previously hidden food items. Chickadees rely predominantly on vision for navigation, as in humans. They also form many independent memories at precisely identifiable times. Finally, the neural pathways carrying visual input from the retina to the hippocampus in birds are relatively simple. I will exploit these features to dissect the transformation of lower-order visual inputs into the observed spatial firing patterns and memory functions of the hippocampus. I will (1) dissociate visual and spatial representations in the chickadee hippocampus using a novel discrete foraging task, (2) compare the visual and spatial representations in a visual cortex analog that provides monosynaptic input to the hippocampus, and (3) causally test the role of this visual input pathway for hippocampal coding and memory. Hippocampal circuits are highly similar in mammals and birds, so the results promise to reveal fundamental computations that are shared across vertebrates. Further, this project is broadly relevant for hippocampal disorders including Alzheimer’s disease, which is associated with visuospatial deficits and altered eye movements. Candidate and Career Goals: I aim to establish an independent lab studying how visual information is processed by memory circuits. I have a background in engineering and vision-related systems neuroscience, and have made foundational discoveries in the hippocampus of food-caching birds, including recently publishing the first neural recordings in these species. This history, combined with the scientific and professional training planned during the K99 phase of this project, positions me uniquely to succeed in my goals. Career Development Plan: I will be trained by mentors Dr. Dmitriy Aronov and Dr. Larry Abbott at Columbia University, and Dr. Elizabeth Buffalo at the University of Washington. Dr. Aronov is an expert in the experimental techniques I will learn, while Dr. Abbott is a world-renowned theoretical neuroscientist who will provide training in the analysis and modelling of complex datasets. Dr. Buffalo pioneered the study of visual representations in the primate hippocampus and will advise on task design and analysis, while ensuring that the project is broadly relevant to hippocampus researchers across species. All mentors will provide career development training and advice for my transition to independence.