Our research

We use cognitive neuroscience approaches to better understand how memory works. We incorporate techniques like functional neuroimaging (fMRI) and non-invasive brain stimulation (TMS) into experiments designed to track the formation, transformation, and use of new memories.

How does prior knowledge interact with new memories?

Every new experience is made up of re-combinations of people, places, and things that we have previously encountered. How does this prior knowledge shape new memory formation, and how does what we already know interact with what we’ve recently experienced to build new knowledge? To answer these questions, we investigate interactions between the hippocampal memory system, which supports memory for specific events, and cortical memory systems, which are involved in memory for general knowledge and concepts.

In several lines of research, we investigate how different aspects of semantic knowledge are privileged in their impact on new memories. This line of research explores the many ways that the organization and content of semantic knowledge can influence new memory formation: in terms of the features of concepts, the way that they are related, the impact of emotion, thematic relations—extrinsic links between concepts, such as their functional ties or spatial-temporal co-occurrences in events and scenarios (e.g., dog and leash)—and how semantic knowledge is shaped by individual lived experiences.

We have also developed several causal and behavioral manipulations to understand how access to semantic knowledge at different phases of a memory (encoding, consolidation, retrieval) impacts the transformations in memory that take place over time. To this end, we use TMS to test how the timing of access to category knowledge impacts new memory formation and have developed novel behavioral experiments to more fully understand whether a new memory is distorted during encoding, or if distortions in memory arise at retrieval via the on-the-fly integration of episodic detail and prior knowledge.

How do memories change over time in the brain?

When we remember an experience, we re-create, or ‘reinstate’, the pattern of activity in the brain that was created during our original experience. However, over time, memories undergo many changes – we might forget small, peripheral details of events, while integrating experiences that were related or overlapping. For instance, you may not remember every time you’ve visited your favorite restaurant, but you can probably recall how your favorite dish tastes. It is currently unknown how these sources of information are combined in the brain, whether the neural regions underlying the different components cooperate, compete, or operate independently during memory encoding and retrieval.

Key insights into this question can be drawn from current explanations of how episodic memories change over time, via the shifting representation of memory traces in the hippocampus and across cortex (systems-level consolidation). We use fMRI to examine how memories are reinstated in the brain, and how consolidation changes the reinstatement of memories over time. Behaviorally, we use memory updating paradigms to investigate how individual components of memories can change over time, through post-learning processing of the memories, and with the introduction of conflicting misinformation.

What aspects of our experience are prioritized by consolidation?

Memory consolidation is the process by which the brain strengthens (and changes) new memories. One way that this may happen is through ‘replay’, when neurons involved in encoding of an experience fire again during post-learning periods of sleep and rest. However, not all memories are replayed equally. Instead, this replay process may selectively prioritize elements of a recent experience. To examine which features are preferentially reactivated, we use fMRI to measure brain signals related to replay that help us to understand what elements of our recent experience that are prioritized by consolidation.

Interestingly, being able to rely on prior knowledge during new learning can speed the consolidation of a new memory, regardless of whether it is consistent with prior knowledge or conflicts with it. This suggests that rapid consolidation can lead to very different memory outcomes that are usually studied separately: facilitated integration and exacerbated distortions. The overarching goals of this line of work are to (1) investigate the neural dynamics by which prior knowledge alters the consolidation of new memories and (2) determine whether the same neural dynamics that enable a memory’s rapid consolidation can result in either facilitated integration or extreme distortions, depending on its congruency with prior knowledge.

How Do Mind-Wandering and Memory Consolidation Interact?

Spontaneous thought is often thought of as a problem: a failure of attention or executive control. However, the high natural prevalence in daily life may signify adaptive, or even essential, roles in supporting basic cognitive functions. Specifically, spontaneous thoughts may serve a role in selecting mental contents for memory consolidation, which in turn stabilizes newly learned information for its longterm retention. We have outlined a framework for bringing together these two areas of research (Joshi, Tompary, & Kucyi, Current Opinions in Behavioral Sciences, in press). We use real-time fMRI to efficiently sample mental experiences during neural reactivation, to directly test the temporal relationship between memory reactivation and global brain activity that tracks spontaneous thoughts. We also investigate how specific aspects of spontaneous thoughts interact with memory consolidation, as well as how potential modulators, such as screen time, intentionality, and intensity, may uniquely scale with subsequent memory.

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