scholarly journals The human hippocampus plays a time-limited role in retrieving autobiographical memories

2020 ◽  
Author(s):  
Adrian W. Gilmore ◽  
Alina Quach ◽  
Sarah E. Kalinowski ◽  
Estefanía I. Gonzalez-Araya ◽  
Stephen J. Gotts ◽  
...  

ABSTRACTThe necessity of the human hippocampus for remote autobiographical recall remains fiercely debated. The standard model of consolidation predicts a time-limited role for the hippocampus, but the competing multiple trace/trace transformation theories posit indefinite involvement. Lesion evidence remains inconclusive, and the inferences one can draw from fMRI have been limited by reliance on covert (silent) recall, which obscures dynamic, moment-to-moment content of retrieved memories. Here, we capitalized on advances in fMRI denoising to employ overtly spoken recall. Forty participants retrieved recent and remote memories, describing each for approximately two minutes. Details associated with each memory were identified and modeled in the fMRI timeseries data using a variant of the Autobiographical Interview procedure, and activity associated with the recall of recent and remote memories was then compared. Posterior hippocampal regions exhibited temporally-graded activity patterns (recent events > remote events), as did several regions of frontal and parietal cortex. Consistent with predictions of the standard model, recall-related hippocampal activity differed from a non-autobiographical control task only for recent, and not remote, events. Task-based connectivity between posterior hippocampal regions and others associated with mental scene construction also exhibited a temporal gradient, with greater connectivity accompanying the recall of recent events. These findings support predictions of the standard model of consolidation and demonstrate the potential benefits of overt recall in neuroimaging experiments.

2021 ◽  
Vol 118 (12) ◽  
pp. e2023069118
Author(s):  
Adrian W. Gilmore ◽  
Alina Quach ◽  
Sarah E. Kalinowski ◽  
Estefanía I. González-Araya ◽  
Stephen J. Gotts ◽  
...  

The necessity of the human hippocampus for remote autobiographical recall remains fiercely debated. The standard model of consolidation predicts a time-limited role for the hippocampus, but the competing multiple trace/trace transformation theories posit indefinite involvement. Lesion evidence remains inconclusive, and the inferences one can draw from functional MRI (fMRI) have been limited by reliance on covert (silent) recall, which obscures dynamic, moment-to-moment content of retrieved memories. Here, we capitalized on advances in fMRI denoising to employ overtly spoken recall. Forty participants retrieved recent and remote memories, describing each for approximately 2 min. Details associated with each memory were identified and modeled in the fMRI time-series data using a variant of the Autobiographical Interview procedure, and activity associated with the recall of recent and remote memories was then compared. Posterior hippocampal regions exhibited temporally graded activity patterns (recent events > remote events), as did several regions of frontal and parietal cortex. Consistent with predictions of the standard model, recall-related hippocampal activity differed from a non-autobiographical control task only for recent, and not remote, events. Task-based connectivity between posterior hippocampal regions and others associated with mental scene construction also exhibited a temporal gradient, with greater connectivity accompanying the recall of recent events. These findings support predictions of the standard model of consolidation and demonstrate the potential benefits of overt recall in neuroimaging experiments.


2021 ◽  
Author(s):  
Adrian W. Gilmore ◽  
Anna M. Agron ◽  
Estefaniá I. González-Araya ◽  
Stephen J. Gotts ◽  
Alex Martin

Recent years have seen an increase in the use of multi-echo fMRI designs by cognitive neuroscientists. Acquiring multiple echoes allows one to reduce thermal noise and identify nuisance signal components in BOLD data (Kundu et al., 2012). At the same time, multi-echo acquisitions increase data processing complexity and may incur a cost to the temporal and spatial resolution of the acquired data. Here, we re-examine a multi-echo dataset (Gilmore et al., 2021) analyzed using multi-echo ICA (ME-ICA) and focused on hippocampal activity during the overly spoken recall of recent and remote autobiographical memories. The goal of the present series of analyses was to determine if ME-ICA's theoretical denoising benefits might lead to a practical difference in the overall conclusions reached. Compared to single echo data, ME-ICA led to qualitatively different conclusions regarding hippocampal contributions to autobiographical recall: whereas the single echo analysis largely failed to reveal hippocampal activity relative to an active baseline, ME-ICA results supported predictions of the Standard Model of Consolidation and a time limited hippocampal involvement (Alvarez and Squire, 1994). These data provide a practical example of the benefits multi-echo denoising in a naturalistic memory paradigm and demonstrate how they can be used to address long-standing theoretical questions.


2021 ◽  
Author(s):  
Jordan Crivelli-Decker ◽  
Alex Clarke ◽  
Seongmin Park ◽  
Derek Huffman ◽  
Erie Boorman ◽  
...  

Recent work in cognitive and systems neuroscience has suggested that the hippocampus might support planning, imagination, and navigation by forming "cognitive maps" that capture the structure of physical spaces, tasks, and situations. Critically, navigation involves planning within a context and disambiguating similar contexts to reach a goal. We examined hippocampal activity patterns in humans during a goal-directed navigation task to examine how contextual and goal information are incorporated in the construction and execution of navigational plans. Results demonstrate that, during planning, the hippocampus carries a context-specific representation of a future goal. Importantly, this effect could not be explained by stimulus or spatial information alone. During navigation, we observed reinstatement of activity patterns in the hippocampus ahead of participants' required actions, which was strongest for behaviorally relevant points in the sequence. These results suggest that, rather than simply representing overlapping associations, hippocampal activity patterns are powerfully shaped by context and goals.


2019 ◽  
Author(s):  
Eda Mizrak ◽  
Nichole R. Bouffard ◽  
Laura A. Libby ◽  
Erie Boorman ◽  
Charan Ranganath

ABSTRACTMemories of previous experiences can be used to guide future decisions in similar situations. Recent evidence suggests that the hippocampus might support decision-making by forming representations that capture common elements across different events (e.g., “cognitive maps” or “schemas”). Here, we used functional magnetic resonance imaging (fMRI) to test how the human hippocampus represents decision relevant information extracted from previous experiences. Participants performed a task in which they learned to predict a customer preference for foods in four different store contexts. The task was structured such that we could examine the degree to which hippocampal representations reflected generalized information about the store contexts, food items, and also the kind of information that was relevant to decisions on a given trial. Results showed that hippocampal activity patterns carried information about the kind of information that was currently relevant to a decision. Across different store contexts, hippocampal representations differentiated between context-determined (deterministic) decisions and context-invariant (probabilistic) decisions. Results also showed that information about store contexts was represented by the hippocampus, but contrary to what might be expected, similar contexts were hyper-differentiated from one another. These results suggest that the hippocampus may support decision-making by systematically mapping relationships between task relevant information, decisions, and outcomes.


Author(s):  
Sterling P. Newberry

At the 1958 meeting of our society, then known as EMSA, the author introduced the concept of microspace and suggested its use to provide adequate information storage space and the use of electron microscope techniques to provide storage and retrieval access. At this current meeting of MSA, he wishes to suggest an additional use of the power of the electron microscope.The author has been contemplating this new use for some time and would have suggested it in the EMSA fiftieth year commemorative volume, but for page limitations. There is compelling reason to put forth this suggestion today because problems have arisen in the “Standard Model” of particle physics and funds are being greatly reduced just as we need higher energy machines to resolve these problems. Therefore, any techniques which complement or augment what we can accomplish during this austerity period with the machines at hand is worth exploring.


2019 ◽  
Author(s):  
Adib Rifqi Setiawan

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.


2019 ◽  
Author(s):  
Adib Rifqi Setiawan

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.


2014 ◽  
Vol 36 (10) ◽  
pp. 2156-2167
Author(s):  
Qiang LI ◽  
Deng-Guo FENG ◽  
Li-Wu ZHANG ◽  
Zhi-Gang GAO

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