Research Project
10275796
PROJECT SUMMARY Our ability to remember the images that we have encountered is remarkable - we can correctly determine whether we have seen an image before after viewing thousands, each only for a few seconds. While we have some understanding of the brain areas involved in supporting `visual recognition memory' (including inferotemporal cortex (IT), perirhinal cortex and the hippocampus), the specific contributions that these brain areas make to visual recognition memory are poorly understood. The proposed study leverages the fact that humans and other primates remember images with substantial visual detail, as this places important constraints on the neural mechanisms that support visual recognition memory. The proposed study also focuses on understanding the neural mechanisms that support visual memory using the `Mnemonic Similarity task', which has been linked to clinical pathology in an array of human disorders including age-related dementia, depression, and Schizophrenia. To date, investigations of the neural mechanisms that support visual recognition memory have been limited by the fact that visual memories are stored following single image exposures, whereas the techniques that exist to fit and evaluate models of neural mechanism are only effective when applied to data in which the same condition was repeated across many trials. In this proposal, we introduce novel data analysis tools to evaluate single-exposure visual memory models with single-unit data. We also introduce the first animal model demonstrated to reflect human-like Mnemonic Similarity behavior, as well as neural data, recorded at single unit resolution. In Aim 1, we focus on IT and perirhinal cortex, including tests of the hypothesis that these brain areas contribute to shaping the visual fidelity of visual recognition memory through sparsifying repetition suppression. In Aim 2, we focus on the hippocampus, including tests of the hypothesis that it contributes by applying pattern separation to its incoming visual inputs before memory storage. In Aim 3, we probe how the same neural circuits responsible for storing visually detailed memories are also capable of generalizing that information to new instances. Together, these results will, for the first time, describe the differential contributions of IT, perirhinal cortex and the hippocampus to shaping the remarkable visual fidelity of visual recognition memory behavior.
