UC Berkeley

How people absorb and recall information about the world around them remains a central mystery of neuroscience. One popular framework for studying this process, systems consolidation, describes how episodic memories are initially encoded during an experience, consolidated into long term memory afterward, and recalled later. Each of these processes has been mapped to specific types of neural activity in specific brain regions. This mapping is incomplete. New progress each year reveals more details about how our memory system functions and new insights into the neural activity of our brains. One such type of neural activity is replay events. These events, typically investigated in rodent brains, allow an animal to simulate paths through an environment. A large body of research has shown clear connections between replay events and the consolidation phase of systems consolidation.

This dissertation expands on this research in two ways. In my behavioral results, I describe a series of experiments which suggest that replay may be critical for all three parts of systems consolidation, including the encoding, consolidation, and recall phases. In these experiments, we interfere with the rats’ ability to generate replay events and observe a corresponding loss of memory for salient locations in an environment. These experiments employ closed-loop methods to interact with ongoing neural activity in real time, by delivering feedback whenever a replay event occurs. In my other chapter, I present a tool designed to greatly expand what experiments are possible in such closed-loop interactions. While most interactions involve either detection of all replay events or some coarse categorization, this tool allows experimenters to read out the simulated path through the environment directly as the replay event is occurring.