PROJECT SUMMARY/ABSTRACT The hippocampus plays a critical role in the organization of memories. Previous studies on the nature of neural representations in the hippocampus have focused on spatial representations by hippocampal neurons, but many studies in humans and animals indicate a broader role for the hippocampus in memory organization. Representational Similarity Analysis, which has been very successful in revealing the organization of neural representations in other domains, will be employed to explore how hippocampal networks organize memories that are distinguished by temporal context and by specific salient cues and rules; and how multiple memory representations are integrated and stabilized over time. These experiments employ a combination of multi- electrode recording in rats, state-of-the-art calcium imaging in behaving mice, and novel neural population analyses, to generate a new understanding of neural network representations. These studies are of high translational potential because cognition dependent on memory organization is impaired in mental disorders including schizophrenia.

PROJECT NARRATIVE The experiments described in this proposal will provide major new insights into how memories are organized by neural networks in the hippocampus in rodents performing memory tasks that model human declarative memory. These studies are of high translational potential because memory dependent on these networks is compromised in mental disorders, and understanding the basic mechanisms of neural networks provides a platform for testing possible therapies.