Assistant Professor, Psychology
Ph.D. NYU Department of Psychology
Research Interests: Cognitive Neuroscience, Learning, Memory, Decision Making
Overview: Why does our subjective experience of the world feel structured when, in fact, it is continuous? How do our internal and external states influence this structure? Research in the DuBrow lab seeks to understand how we learn the structure of our environments and how we use that structure to organize our memories and guide our decisions. Using neuroimaging methods, we investigate how neural representations can mirror the true structure of the external world, and, at the same time, distort that structure to achieve behavioral goals. By mapping between the brain and behavior, we hope to shed light on fundamental organizing principles in human cognition.
Decision-making Increases Episodic Memory via Postencoding Consolidation.
J Cogn Neurosci. 2018 Jul 31;:1-10
Authors: Murty VP, DuBrow S, Davachi L
The ability for individuals to actively make decisions engages regions within the mesolimbic system and enhances memory for chosen items. In other behavioral contexts, mesolimbic engagement has been shown to enhance episodic memory by supporting consolidation. However, research has yet to investigate how consolidation may support interactions between decision-making and episodic memory. Across two studies, participants encoded items that were covered by occluder screens and could either actively decide which of two items to uncover or were preselected by the experimenter. In Study 1, we show that active decision-making reduces forgetting rates across an immediate and 24-hr memory test, a behavioral marker of consolidation. In Study 2, we use functional neuroimaging to characterize putative neural markers of memory consolidation by measuring interactions between the hippocampus and perirhinal cortex (PRC) during a postencoding period that reexposed participants to elements of the decision-making context without exposing them to memoranda. We show that choice-related striatal engagement is associated with increased postencoding hippocampal-PRC interactions. Finally, we show that a previous reported relationship between choice-related striatal engagement and long-term memory is accounted for by these postencoding hippocampal-PRC interactions. Together, these findings support a model by which actively deciding to encode information enhances memory consolidation to preserve episodic memory for outcomes, a process that may be facilitated by reexposure to the original decision-making context.
PMID: 30063181 [PubMed - as supplied by publisher]
Differential patterns of contextual organization of memory in first-episode psychosis.
NPJ Schizophr. 2018 Feb 15;4(1):3
Authors: Murty VP, McKinney RA, DuBrow S, Jalbrzikowski M, Haas GL, Luna B
Contextual information is used to support and organize episodic memory. Prior research has reliably shown memory deficits in psychosis; however, little research has characterized how this population uses contextual information during memory recall. We employed an approach founded in a computational framework of free recall to quantify how individuals with first episode of psychosis (FEP, N = 97) and controls (CON, N = 55) use temporal and semantic context to organize memory recall. Free recall was characterized using the Hopkins Verbal Learning Test-Revised (HVLT-R). We compared FEP and CON on three measures of free recall: proportion recalled, temporal clustering, and semantic clustering. Measures of temporal/semantic clustering quantified how individuals use contextual information to organize memory recall. We also assessed to what extent these measures relate to antipsychotic use and differentiated between different types of psychosis. We also explored the relationship between these measures and intelligence. In comparison to CON, FEP had reduced recall and less temporal clustering during free recall (p < 0.05, Bonferroni-corrected), and showed a trend towards greater semantic clustering (p = 0.10, Bonferroni-corrected). Within FEP, antipsychotic use and diagnoses did not differentiate between free recall accuracy or contextual organization of memory. IQ was related to free recall accuracy, but not the use of contextual information during recall in either group (p < 0.05, Bonferroni-corrected). These results show that in addition to deficits in memory recall, FEP differed in how they organize memories compared to CON.
PMID: 29449557 [PubMed]
Does mental context drift or shift?
Curr Opin Behav Sci. 2017 Oct;17:141-146
Authors: DuBrow S, Rouhani N, Niv Y, Norman KA
Theories of episodic memory have generally proposed that individual memory traces are linked together by a representation of context that drifts slowly over time. Recent data challenge the notion that contextual drift is always slow and passive. In particular, changes in one's external environment or internal model induce discontinuities in memory that are reflected in sudden changes in neural activity, suggesting that context can shift abruptly. Furthermore, context change effects are sensitive to top-down goals, suggesting that contextual drift may be an active process. These findings call for revising models of the role of context in memory, in order to account for abrupt contextual shifts and the controllable nature of context change.
PMID: 29335678 [PubMed]
Event Boundaries Trigger Rapid Memory Reinstatement of the Prior Events to Promote Their Representation in Long-Term Memory.
Curr Biol. 2017 Nov 20;27(22):3499-3504.e4
Authors: Sols I, DuBrow S, Davachi L, Fuentemilla L
Although everyday experiences unfold continuously over time, shifts in context, or event boundaries, can influence how those events come to be represented in memory [1-4]. Specifically, mnemonic binding across sequential representations is more challenging at context shifts, such that successful temporal associations are more likely to be formed within than across contexts [1, 2, 5-9]. However, in order to preserve a subjective sense of continuity, it is important that the memory system bridge temporally adjacent events, even if they occur in seemingly distinct contexts. Here, we used pattern similarity analysis to scalp electroencephalographic (EEG) recordings during a sequential learning task [2, 3] in humans and showed that the detection of event boundaries triggered a rapid memory reinstatement of the just-encoded sequence episode. Memory reactivation was detected rapidly (∼200-800 ms from the onset of the event boundary) and was specific to context shifts that were preceded by an event sequence with episodic content. Memory reinstatement was not observed during the sequential encoding of events within an episode, indicating that memory reactivation was induced specifically upon context shifts. Finally, the degree of neural similarity between neural responses elicited during sequence encoding and at event boundaries correlated positively with participants' ability to later link across sequences of events, suggesting a critical role in binding temporally adjacent events in long-term memory. Current results shed light onto the neural mechanisms that promote episodic encoding not only for information within the event, but also, importantly, in the ability to link across events to create a memory representation of continuous experience.
PMID: 29129536 [PubMed - indexed for MEDLINE]
Commentary: Distinct neural mechanisms for remembering when an event occurred.
Front Psychol. 2017;8:189
Authors: DuBrow S, Davachi L
PMID: 28270781 [PubMed]
Temporal binding within and across events.
Neurobiol Learn Mem. 2016 10;134 Pt A:107-114
Authors: DuBrow S, Davachi L
Remembering the order in which events occur is a fundamental component of episodic memory. However, the neural mechanisms supporting serial recall remain unclear. Behaviorally, serial recall is greater for information encountered within the same event compared to across event boundaries, raising the possibility that contextual stability may modulate the cognitive and neural processes supporting serial encoding. In the present study, we used fMRI during the encoding of consecutive face and object stimuli to elucidate the neural encoding signatures supporting subsequent serial recall behavior both within and across events. We found that univariate BOLD activation in both the middle hippocampus and left ventrolateral prefrontal cortex (PFC) was associated with subsequent serial recall of items that occur across event boundaries. By contrast, successful serial encoding within events was associated with increased functional connectivity between the hippocampus and ventromedial PFC, but not with univariate activation in these or other regions. These findings build on evidence implicating hippocampal and PFC processes in encoding temporal aspects of memory. They further suggest that these encoding processes are influenced by whether binding occurs within a stable context or bridges two adjacent but distinct events.
PMID: 27422018 [PubMed - indexed for MEDLINE]
The simple act of choosing influences declarative memory.
J Neurosci. 2015 Apr 22;35(16):6255-64
Authors: Murty VP, DuBrow S, Davachi L
Individuals value the opportunity to make choices and exert control over their environment. This perceived sense of agency has been shown to have broad influences on cognition, including preference, decision-making, and valuation. However, it is unclear whether perceived control influences memory. Using a combined behavioral and functional magnetic resonance imaging approach, we investigated whether imbuing individuals with a sense of agency over their learning experience influences novel memory encoding. Participants encoded objects during a task that manipulated the opportunity to choose. Critically, unlike previous work on active learning, there was no relationship between individuals' choices and the content of memoranda. Despite this, we found that the opportunity to choose resulted in robust, reliable enhancements in declarative memory. Neuroimaging results revealed that anticipatory activation of the striatum, a region associated with decision-making, valuation, and exploration, correlated with choice-induced memory enhancements in behavior. These memory enhancements were further associated with interactions between the striatum and hippocampus. Specifically, anticipatory signals in the striatum when participants are alerted to the fact that they will have to choose one of two memoranda were associated with encoding success effects in the hippocampus on a trial-by-trial basis. The precedence of the striatal signal in these interactions suggests a modulatory relationship of the striatum over the hippocampus. These findings not only demonstrate enhanced declarative memory when individuals have perceived control over their learning but also support a novel mechanism by which these enhancements emerge. Furthermore, they demonstrate a novel context in which mesolimbic and declarative memory systems interact.
PMID: 25904779 [PubMed - indexed for MEDLINE]
How the hippocampus preserves order: the role of prediction and context.
Trends Cogn Sci. 2015 Feb;19(2):92-9
Authors: Davachi L, DuBrow S
Remembering the sequence of events is critical for deriving meaning from our experiences and guiding behavior. Prior investigations into the function of the human hippocampus have focused on its more general role in associative binding, but recent work has focused on understanding its specific role in encoding and preserving the temporal order of experiences. In this review we summarize recent work in humans examining hippocampal contributions to sequence learning. We distinguish the learning of sequential relationships through repetition from the rapid, episodic acquisition of sequential associations. Taken together, this research begins to clarify the link between hippocampal representations and the preservation of the order of events.
PMID: 25600586 [PubMed - indexed for MEDLINE]