scholarly journals Offline ventral subiculum-ventral striatum serial communication is required for spatial memory consolidation

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
G. Torromino ◽  
L. Autore ◽  
V. Khalil ◽  
V. Mastrorilli ◽  
M. Griguoli ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Memory Consolidation ◽  
Ventral Striatum ◽  
Spatial Information ◽  
Hippocampal Formation ◽  
Critical Role ◽  
Brain Regions ◽  
Complex Information ◽  
Line Cross ◽  
Insight Into

AbstractThe hippocampal formation is considered essential for spatial navigation. In particular, subicular projections have been suggested to carry spatial information from the hippocampus to the ventral striatum. However, possible cross-structural communication between these two brain regions in memory formation has thus far been unknown. By selectively silencing the subiculum–ventral striatum pathway we found that its activity after learning is crucial for spatial memory consolidation and learning-induced plasticity. These results provide new insight into the neural circuits underlying memory consolidation and establish a critical role for off-line cross-regional communication between hippocampus and ventral striatum to promote the storage of complex information.

scholarly journals Hebbian plasticity in parallel synaptic pathways: A circuit mechanism for systems memory consolidation

2021 ◽  
Vol 17 (12) ◽  
pp. e1009681
Author(s):  
Michiel W. H. Remme ◽  
Urs Bergmann ◽  
Denis Alevi ◽  
Susanne Schreiber ◽  
Henning Sprekeler ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Computational Models ◽  
Hippocampal Formation ◽  
Spatial Scales ◽  
Single Cells ◽  
Brain Regions ◽  
Quantitative Agreement ◽  
Long Term Memory ◽  
Hebbian Plasticity ◽  
Mathematical Analyses

Systems memory consolidation involves the transfer of memories across brain regions and the transformation of memory content. For example, declarative memories that transiently depend on the hippocampal formation are transformed into long-term memory traces in neocortical networks, and procedural memories are transformed within cortico-striatal networks. These consolidation processes are thought to rely on replay and repetition of recently acquired memories, but the cellular and network mechanisms that mediate the changes of memories are poorly understood. Here, we suggest that systems memory consolidation could arise from Hebbian plasticity in networks with parallel synaptic pathways—two ubiquitous features of neural circuits in the brain. We explore this hypothesis in the context of hippocampus-dependent memories. Using computational models and mathematical analyses, we illustrate how memories are transferred across circuits and discuss why their representations could change. The analyses suggest that Hebbian plasticity mediates consolidation by transferring a linear approximation of a previously acquired memory into a parallel pathway. Our modelling results are further in quantitative agreement with lesion studies in rodents. Moreover, a hierarchical iteration of the mechanism yields power-law forgetting—as observed in psychophysical studies in humans. The predicted circuit mechanism thus bridges spatial scales from single cells to cortical areas and time scales from milliseconds to years.

scholarly journals An insula-driven network computes decision uncertainty and promotes abstinence in chronic cocaine users

2020 ◽  
Author(s):  
Ju-Chi Yu ◽  
Vincenzo G. Fiore ◽  
Richard W. Briggs ◽  
Jacquelyn Braud ◽  
Katya Rubia ◽  
...  
Keyword(s):  
Ventral Striatum ◽  
Critical Role ◽  
Insular Cortex ◽  
Brain Regions ◽  
Anterior Cingulate ◽  
Decision Task ◽  
Dorsal Anterior Cingulate Cortex ◽  
Excitatory Connection ◽  
Chronic Cocaine

AbstractThe anterior insular cortex (AIC) and its interconnected brain regions have been associated with both addiction and decision-making under uncertainty. However, the causal interactions in this uncertainty-encoding neurocircuitry and how these neural dynamics impact relapse remain elusive. Here, we used model-based fMRI to measure choice uncertainty in a motor decision task in 61 individuals with cocaine use disorder (CUD) and 25 healthy controls. CUD participants were assessed before discharge from a residential treatment program and followed for up to 24 weeks. We found that choice uncertainty was tracked by the AIC, dorsal anterior cingulate cortex (dACC), and ventral striatum (VS), across participants. Stronger activations in these regions measured pre-discharge predicted longer abstinence after discharge in individuals with CUD. Dynamic causal modelling revealed an AIC-to-dACC directed connectivity modulated by uncertainty in controls, but a dACC-to-AIC connectivity in CUD participants. This reversal was mostly driven by early-relapsers (<30 days). Furthermore, CUD individuals who displayed a stronger AIC-to-dACC excitatory connection during uncertainty encoding remained abstinent for longer periods. These findings reveal a critical role of an AIC-driven, uncertainty-encoding neurocircuitry in protecting against relapse and promoting abstinence.

scholarly journals Persistence of Hippocampal and Striatal Multivoxel Patterns during Awake Rest after Motor Sequence Learning

2021 ◽  
Author(s):  
Bradley R. King ◽  
Mareike A. Gann ◽  
Dante Mantini ◽  
Julien Doyon ◽  
Genevieve Albouy
Keyword(s):  
Motor Learning ◽  
Sequence Learning ◽  
Memory Consolidation ◽  
Primary Motor Cortex ◽  
Critical Role ◽  
Brain Regions ◽  
Response Patterns ◽  
Motor Sequence Learning ◽  
Motor Sequence ◽  
Task Practice

Memory consolidation is thought to be mediated by the offline reactivation of brain regions recruited during initial learning. Evidence for hippocampal reactivation in humans comes from studies showing that hippocampal response patterns elicited during learning can persist into subsequent rest intervals. Such investigations have largely been limited to declarative memory, which is surprising given the critical role of the hippocampus in motor memory processes. The primary goal of this study was therefore to investigate whether motor learning induces persistence of hippocampal patterns into subsequent rest. Based on their critical roles in motor learning and memory consolidation processes, we also assessed persistence in the striatum and primary motor cortex (M1). Functional magnetic resonance imaging (fMRI) data were recorded during motor learning as well as pre- and post-learning resting periods from 55 young healthy adults (males and females). Patterns of brain responses were assessed with intra- and inter-regional multivoxel correlation structure (MVCS). Intra-regional multivoxel patterns during motor sequence learning within the hippocampus and the striatum - but not within M1 - were more similar to post-learning as compared to pre-learning resting epochs, indicating persistence of task-related patterns thought to reflect reactivation processes. Interestingly, the multivoxel pattern of hippocampal connectivity with the striatum (i.e., inter-regional MVCS) was strongly dissimilar between post-learning rest and task practice. Altogether, these results provide evidence for the persistence of learning-related response patterns within the hippocampus and striatum into rest following motor learning. They also suggest that striatal-hippocampal connectivity patterns elicited by task practice are reorganized in post-learning waking rest.

scholarly journals Discrete Place Fields of Hippocampal Formation Interneurons

2007 ◽  
Vol 97 (6) ◽  
pp. 4152-4161 ◽  
Author(s):  
W. Bryan Wilent ◽  
Douglas A. Nitz
Keyword(s):  
Spatial Information ◽  
Hippocampal Formation ◽  
Brain Regions ◽  
Place Cells ◽  
Informational Content ◽  
Inhibitory Interneurons ◽  
Spike Discharge ◽  
Principal Cells ◽  
Place Fields ◽  
Spatial Specificity

The spike discharge of hippocampal excitatory principal cells, also called “place cells,” is highly location specific, but the discharge of local inhibitory interneurons is thought to display relatively low spatial specificity. Whereas in other brain regions, such as sensory neocortex, the activity of interneurons is often exquisitely stimulus selective and directly determines the responses of neighboring excitatory neurons, the activity of hippocampal interneurons typically lacks the requisite specificity needed to shape the defined structure of principal cell fields. Here we show that hippocampal formation interneurons have “on” fields (abrupt increases in activity) and “off” fields (abrupt decreases in activity) that are associated with the same location-specific informational content, spatial resolution, and dependency on context as the “place fields” of CA1 principal cells. This establishes that interneurons have well-defined place fields, thus having important implications for understanding how the hippocampus represents spatial information.

scholarly journals The Parahippocampal Cortex and its Functional Connection with the Hippocampus are Critical for Nonnavigational Spatial Memory in Macaques

2020 ◽  
Author(s):  
Elyssa M LaFlamme ◽  
Hannah F Waguespack ◽  
Patrick A Forcelli ◽  
Ludise Malkova
Keyword(s):  
Spatial Memory ◽  
Search Task ◽  
Spatial Information ◽  
Critical Role ◽  
Functional Connection ◽  
Parahippocampal Cortex ◽  
Major Route ◽  
Color Cues

Abstract The Hamilton Search Task (HST) is a test of nonnavigational spatial memory that is dependent on the hippocampus. The parahippocampal cortex (PHC) is a major route for spatial information to reach the hippocampus, but the extent to which the PHC and hippocampus function independently of one another in the context of nonnavigational spatial memory is unclear. Here, we tested the hypotheses that (1) bilateral pharmacological inactivation of the PHC would impair HST performance, and (2) that functional disconnection of the PHC and hippocampus by contralateral (crossed) inactivation would likewise impair performance. Transient inactivation of the PHC impaired HST performance most robustly with 30 s intertrial delays, but not when color cues were introduced. Functional disconnection of the PHC and hippocampus, but not separate unilateral inactivation of either region, also selectively impaired long-term spatial memory. These findings indicate a critical role for the PHC and its interactions with the hippocampus in nonnavigational spatial memory.

scholarly journals Hummingbirds have a greatly enlarged hippocampal formation

2012 ◽  
Vol 8 (4) ◽  
pp. 657-659 ◽  
Author(s):  
Brian J. Ward ◽  
Lainy B. Day ◽  
Steven R. Wilkening ◽  
Douglas R. Wylie ◽  
Deborah M. Saucier ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Hippocampal Formation ◽  
Relative Size ◽  
Brain Regions ◽  
Temporal Information ◽  
Laboratory Studies ◽  
Nectar Content

Both field and laboratory studies demonstrate that hummingbirds (Apodiformes, Trochilidae) have exceptional spatial memory. The complexity of spatial–temporal information that hummingbirds must retain and use daily is probably subserved by the hippocampal formation (HF), and therefore, hummingbirds should have a greatly expanded HF. Here, we compare the relative size of the HF in several hummingbird species with that of other birds. Our analyses reveal that the HF in hummingbirds is significantly larger, relative to telencephalic volume, than any bird examined to date. When expressed as a percentage of telencephalic volume, the hummingbird HF is two to five times larger than that of caching and non-caching songbirds, seabirds and woodpeckers. This HF expansion in hummingbirds probably underlies their ability to remember the location, distribution and nectar content of flowers, but more detailed analyses are required to determine the extent to which this arises from an expansion of HF or a decrease in size of other brain regions.

scholarly journals Hippocampal CA2 ripples recruit social replay and promote social memory

2020 ◽  
Author(s):  
Oliva Azahara ◽  
Fernández-Ruiz Antonio ◽  
Leroy Felix ◽  
Siegelbaum A. Steven
Keyword(s):  
Spatial Memory ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Social Memory ◽  
Declarative Memory ◽  
Critical Role ◽  
Sensory Information ◽  
General Mechanism ◽  
Recent Experience ◽  
Wide Range

The consolidation of spatial memory depends on the reactivation (‘replay’) of hippocampal place cells that were active during recent behavior. These reactivations are observed during sharp wave-ripples (SWRs), synchronous oscillatory events that occur during slow-wave sleep1–9 and whose disruption impairs spatial memory consolidation 4,6,7,9. Although the hippocampus encodes a wide range of non-spatial forms of declarative memory, it is not yet known whether SWRs are necessary for non-spatial memory. Moreover, although SWRs can arise from either the hippocampal CA38 or CA210 regions, the relative importance of these sources for memory consolidation is unknown. Here we examined the role of SWRs during the consolidation of social memory, the ability of an animal to recognize and remember a conspecific, focusing on CA2 because of its critical role in social memory11,12,13. We found that ensembles of CA2 pyramidal neurons that were active during social exploration of novel conspecifics were reactivated during SWRs. Importantly, disruption or enhancement of CA2 SWRs suppressed or prolonged social memory, respectively. Thus, SWR reactivation of hippocampal firing related to recent experience appears to be a general mechanism for binding spatial, temporal and sensory information into high-order memory representations.

scholarly journals Attractor-like spatial representations in the Subicular Complex network

2020 ◽  
Author(s):  
Apoorv Sharma ◽  
Indrajith R. Nair ◽  
Yoganarasimha Doreswamy
Keyword(s):  
Spatial Information ◽  
Spatial Navigation ◽  
Critical Role ◽  
Brain Regions ◽  
Spatial Representations ◽  
Head Direction ◽  
Neural Representations ◽  
Attractor Dynamics ◽  
Reference Map ◽  
Cue Conflict

AbstractDistinct computations are performed at multiple brain regions during encoding of the spatial environments. Neural representations in the hippocampal, entorhinal and head direction (HD) networks during spatial navigation have been clearly documented, while the representational properties of the Subicular Complex (SC) network is rather unexplored, even though it has extensive anatomical connections with various brain regions involved in spatial information processing. Here, we report a global cue controlled highly coherent representation of the cue-conflict environment in the SC network, along with strong coupling between HD cells and Spatial cells. We propose that the attractor dynamics in the SC network might play a critical role in orientation of the spatial representations, thus providing a “reference map” of the environment for further processing at other networks.

scholarly journals Causal role for sleep-dependent reactivation of learning-activated sensory ensembles for fear memory consolidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Brittany C. Clawson ◽  
Emily J. Pickup ◽  
Amy Ensing ◽  
Laura Geneseo ◽  
James Shaver ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Memory Consolidation ◽  
Critical Role ◽  
Visual Presentation ◽  
Fear Memory ◽  
Memory Recall ◽  
Visual Cue ◽  
V1 Neurons ◽  
Targeted Recombination

AbstractLearning-activated engram neurons play a critical role in memory recall. An untested hypothesis is that these same neurons play an instructive role in offline memory consolidation. Here we show that a visually-cued fear memory is consolidated during post-conditioning sleep in mice. We then use TRAP (targeted recombination in active populations) to genetically label or optogenetically manipulate primary visual cortex (V1) neurons responsive to the visual cue. Following fear conditioning, mice respond to activation of this visual engram population in a manner similar to visual presentation of fear cues. Cue-responsive neurons are selectively reactivated in V1 during post-conditioning sleep. Mimicking visual engram reactivation optogenetically leads to increased representation of the visual cue in V1. Optogenetic inhibition of the engram population during post-conditioning sleep disrupts consolidation of fear memory. We conclude that selective sleep-associated reactivation of learning-activated sensory populations serves as a necessary instructive mechanism for memory consolidation.

Postnatal Development of the Hippocampus in Male Albino Rats: A Histomorphometric Study

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
A A A Baraka ◽  
K A Hafez ◽  
A I A Othman ◽  
A M M Sadek
Keyword(s):  
Dentate Gyrus ◽  
Postnatal Development ◽  
Learning And Memory ◽  
Hippocampal Formation ◽  
Critical Role ◽  
Mammalian Brain ◽  
Albino Rats ◽  
Ammon's Horn ◽  
Hippocampus Proper ◽  
Ammon’S Horn

Abstract Introduction In recent year deterioration in cognitive, learning, and memory become one of the significant problems in human life. Hippocampus is a pivotal part of the brain’s limbic system which serves a critical role in memory, learning process and regulating the emotions. In most regions of the brain, neurons are generated only at specific periods of early development, and not born in the adulthood. In contrast, hippocampal neurons are generated throughout development and adult life. The hippocampal dentate gyrus was reported to be one of the few regions of the mammalian brain where neurogenesis continue to occur throughout adulthood. The neurogenesis in the dentate gyrus was thought to play an important role in hippocampus-dependent learning and memory. The hippocampal formation is composed of the hippocampus proper, the dentate gyrus and the subiculum. The hippocampus proper is the largest part and is subdivided into fields designated as Cornu Ammonis or Ammon’s horn (CA) from CA1 to CA4. Ammon's horn is continuous with the subiculum, which acts as the main output source of the hippocampal formation. Aim of the Study To study the postnatal development of the hippocampal formation. Materials and Methods Five male albino rats from the following postnatal ages day 1, week 1, week 2, week3 and week 4 were studied by histological, immunohistochemical, and morphometric methods. Results The general architecture of the hippocampus proper with its polymorphic, pyramidal, and molecular layers was present at day1, whereas the details of the adult structure appeared at week 2. In the dentate gyrus, distinct lamination appeared at week 1 and its maturation continued with the production of neurons at the interhilar zone that peaked at week 2. The number and density of pyramidal axons and dendrites increase by age. Astrocytes increased in size and staining affinity for glial filaments, and acquired a stellate shape with age. Furthermore, the number of granule cell layers increased concomitantly with the increase in thickness of the molecular and polymorphic layers of both the hippocampus proper and the dentate gyrus. Conclusion The important sequences of events in the growth and maturation of the hippocampal formation in male albino rat occurred in the first 2 postnatal weeks.

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