Assistant Professor, Department of Psychology
Ph.D. Stanford University
Postdoctoral Fellowship, Yale University
Research Interests: Cognitive Neuroscience, Memory, Cognitive Control, fMRI Methods
Overview: I am interested in how our perceptual experiences are transformed into memories and how we recreate and selectively recall these experiences. Research in my lab makes use of behavioral and neuroimaging methods (primarily fMRI) with an emphasis on applying machine learning algorithms and multivariate pattern analyses to neuroimaging data in order to understand how memories are represented and transformed in distributed patterns of brain activity.
Some of the specific topics my lab addresses include: What are the cognitive and neural mechanisms that cause forgetting? How is competition between memories signaled and resolved in the brain during retrieval? How do we reduce interference between memories during encoding? Addressing these questions involves understanding the interactions and relative contributions of fronto-parietal cortex and medial temporal lobe structures.
J Neurosci. 2021 Feb 22:JN-RM-2875-20. doi: 10.1523/JNEUROSCI.2875-20.2021. Online ahead of print.
Similarity between memories is a primary cause of interference and forgetting. Exaggerating subtle differences between memories is therefore a potential mechanism for reducing interference. Here, we report a human fMRI study (n = 29, 19 female) that tested whether behavioral and neural expressions of memories are adaptively distorted to reduce interference. Participants learned and repeatedly retrieved object images, some of which were identical except for subtle color differences. Behavioral measures of color memory revealed exaggeration of differences between similar objects. Importantly, greater memory exaggeration was associated with lower memory interference. fMRI pattern analyses revealed that color information in parietal cortex was stronger during memory recall when color information was critical for discriminating competing memories. Moreover, greater representational distance between competing memories in parietal cortex predicted greater color memory exaggeration and lower memory interference. Together, these findings reveal that competition between memories induces adaptive, feature-specific distortions in parietal representations and corresponding behavioral expressions.Significance StatementSimilarity between memories is a primary cause of interference and forgetting. Here, we show that when remembering highly similar objects, subtle differences in the features of these objects are exaggerated in memory in order to reduce interference. These memory distortions are reflected in, and predicted by, overlap of activity patterns in lateral parietal cortex. These findings provide unique insight into how memory interference is resolved and specifically implicate lateral parietal cortex in representing feature-specific memory distortions.
Cortical Representations of Visual Stimuli Shift Locations with Changes in Memory States.
Curr Biol. 2021 Feb 05;:
Authors: Long NM, Kuhl BA
Episodic memory retrieval is thought to rely on reactivation of the same content-sensitive neural activity patterns initially expressed during memory encoding.1-6 Yet there are emerging examples of content representations expressed in different brain regions during encoding versus retrieval.7-14 Although these differences have been observed by comparing encoding and retrieval tasks that differ in terms of perceptual experience and cognitive demands, there are many real-world contexts-e.g., meeting a new colleague who reminds you of an old acquaintance-where the memory system might be intrinsically biased either toward encoding (the new colleague) or retrieval (the old acquaintance).1516 Here, we test whether intrinsic memory states, independent of task demands, determine the cortical location of content representations. In a human fMRI study, subjects (n = 33) viewed object images and were instructed to either encode the current object or retrieve a similar object from memory. Using pattern classifiers, we show that biases toward encoding versus retrieval were reflected in large-scale attentional networks.17-19 Critically, memory states decoded from these networks-even when entirely independent from task instructions-predicted shifts of object representations from visual cortex (encoding) to ventral parietal cortex (retrieval). Finally, visual versus ventral parietal cortices exhibited differential connectivity with the hippocampus during memory encoding versus retrieval, consistent with the idea that the hippocampus mediates cortical shifts in content representations. Collectively, these findings demonstrate that intrinsic biases toward memory encoding versus retrieval determine the specific cortical locations that express content information.
PMID: 33577747 [PubMed - as supplied by publisher]