Ventral Hippocampal Neurons Project Axons Simultaneously to the Medial Prefrontal Cortex and Amygdala in the Rat

2006 ◽  
Vol 96 (4) ◽  
pp. 2134-2138 ◽  
Author(s):  
Akinori Ishikawa ◽  
Shoji Nakamura
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Medial Prefrontal Cortex ◽  
Hippocampal Neurons ◽  
Ventral Hippocampus ◽  
Fluorescent Tracers ◽  
Afferent Projections ◽  
Electrophysiological Evidence ◽  
Antidromic Responses ◽  
The Individual

The ventral hippocampus (VH) may have an important role in spatial memory processes and emotional behaviors through connections with the medial prefrontal cortex (mPFC) and amygdala. Although the mPFC and amygdala receive afferent projections from the VH, it has not been determined whether the individual VH neurons project to both the mPFC and the amygdala. In this study, antidromic responses to the mPFC and amygdala stimulation were evoked in single VH neurons. In addition, VH neurons were retrogradely double-labeled with fluorescent tracers injected in the mPFC and amygdala. VH neurons projecting to both the mPFC and amygdala were predominantly located in the subiculum and CA1 and bifurcated near or at the soma. Our anatomical and electrophysiological evidence for the presence of VH neurons projecting to both the mPFC and amygdala provides a previously unrecognized pathway from the hippocampus that simultaneously activates the mPFC and amygdala.

scholarly journals Transient Inactivation of the Medial Prefrontal Cortex and Ventral Hippocampus Impairs Active Place Avoidance Retrieval on a Rotating Arena

2021 ◽  
Vol 15 ◽  
Author(s):  
Daniela Cernotova ◽  
Ales Stuchlik ◽  
Jan Svoboda
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Medial Prefrontal Cortex ◽  
Ventral Hippocampus ◽  
Avoidance Task ◽  
Exact Role ◽  
Spatial Coordination ◽  
Place Avoidance ◽  
Long Evans

It is well known that communication between the medial prefrontal cortex (mPFC) and the ventral hippocampus (vHPC) is critical for various cognitive and behavioral functions. However, the exact role of these structures in spatial coordination remains to be clarified. Here we sought to determine the involvement of the mPFC and the vHPC in the spatial retrieval of a previously learned active place avoidance task in adult male Long-Evans rats, using a combination of unilateral and bilateral local muscimol inactivations. Moreover, we tested the role of the vHPC-mPFC pathway by performing combined ipsilateral and contralateral inactivations. Our results showed not only bilateral inactivations of either structure, but also the combined inactivations impaired the retrieval of spatial memory, whereas unilateral one-structure inactivations did not yield any effect. Remarkably, muscimol injections in combined groups exerted similar deficits, regardless of whether the inactivations were contralateral or ipsilateral. These findings confirm the importance of these structures in spatial cognition and emphasize the importance of the intact functioning of the vHPC-mPFC pathway.

scholarly journals The generalized spatial representation in the prefrontal cortex is inherited from the hippocampus

2021 ◽  
Author(s):  
Michele Nardin ◽  
Karola Kaefer ◽  
Jozsef Csicsvari
Keyword(s):  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Information Transfer ◽  
Spatial Information ◽  
Spatial Representations ◽  
Spatial Coding ◽  
Spatial Decision Making ◽  
The Individual

Hippocampal and neocortical neural activity is modulated by the position of the individual in space. While hippocampal neurons provide the basis for a spatial map, prefrontal cortical neurons generalize over environmental features. Whether these generalized representations result from a bidirectional interaction with, or are mainly derived from hippocampal spatial representations is not known. By examining simultaneously recorded hippocampal and medial prefrontal neurons, we observed that prefrontal spatial representations show a delayed coherence with hippocampal ones. We also identified subpopulations of cells in the hippocampus and medial prefrontal cortex that formed functional cross-area couplings; these resembled the optimal connections predicted by a probabilistic model of spatial information transfer and generalization. Moreover, cross-area couplings were strongest and had the shortest delay preceding spatial decision-making. Our results suggest that generalized spatial coding in the medial prefrontal cortex is inherited from spatial representations in the hippocampus, and that the routing of information can change dynamically with behavioral demands.

scholarly journals Nucleus reuniens is required for encoding and retrieving precise, hippocampal-dependent contextual fear memories in rats

2018 ◽  
Author(s):  
Karthik R. Ramanathan ◽  
Reed L. Ressler ◽  
Jingji Jin ◽  
Stephen Maren
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Fear Conditioning ◽  
Medial Prefrontal Cortex ◽  
Thalamic Nucleus ◽  
Nmda Receptor Antagonist ◽  
Pavlovian Fear Conditioning ◽  
Contextual Memory ◽  
Nucleus Reuniens ◽  
Contextual Fear

AbstractThe nucleus reuniens (RE) is a ventral midline thalamic nucleus that interconnects the medial prefrontal cortex (mPFC) and hippocampus (HPC). Considerable data indicate that HPC-mPFC circuits are involved in contextual and spatial memory; however, it is not clear whether the RE mediates the acquisition or retrieval of these memories. To examine this question, we inactivated the RE with muscimol before either the acquisition or retrieval of Pavlovian fear conditioning in rats; freezing served as the index of fear. We found that RE inactivation before conditioning impaired the acquisition of contextual freezing, whereas inactivation of the RE prior to retrieval testing increased the generalization of freezing to a novel context; inactivation of the RE did not affect either the acquisition or expression of auditory fear conditioning. Interestingly, contextual conditioning impairments were absent when retrieval testing was also conducted after RE inactivation. Contextual memories acquired under RE inactivation were hippocampal-independent, insofar as contextual freezing in rats conditioned under RE inactivation was insensitive to intra-hippocampal infusions of the NMDA receptor antagonist, D,L-amino-5-phosophonovaleric acid (APV). Together, these data reveal that the RE supports hippocampal-dependent encoding of precise contextual memories that allow discrimination of dangerous from safe contexts. When the RE is inactive, however, alternate neural systems acquire an impoverished contextual memory that is only expressed when the RE is offline.SIGNIFICANCE STATEMENTThe midline thalamic nucleus reuniens (RE) coordinates communication between the hippocampus and medial prefrontal cortex, brain areas critical for contextual and spatial memory. Here we show that temporary pharmacological inactivation of RE impairs the acquisition and precision of contextual fear memories after Pavlovian fear conditioning in rats. However, inactivating the RE prior to retrieval testing restored contextual memory in rats conditioned after RE inactivation. Critically, we show that imprecise contextual memories acquired under RE inactivation are learned independently of the hippocampus. These data reveal that the RE is required for hippocampal-dependent encoding of precise contextual memories to support the discrimination of safe and dangerous contexts.

Medial prefrontal cortex oxytocin-opioid receptors interaction in spatial memory processing in rats

2019 ◽  
Vol 209 ◽  
pp. 112599 ◽  
Author(s):  
Reza Salighedar ◽  
Amir Erfanparast ◽  
Esmaeal Tamaddonfard ◽  
Farhad Soltanalinejad
Keyword(s):  
Prefrontal Cortex ◽  
Spatial Memory ◽  
Medial Prefrontal Cortex ◽  
Opioid Receptors ◽  
Memory Processing

scholarly journals Spectral partitioning identifies individual heterogeneity in the functional network topography of ventral and anterior medial prefrontal cortex

2019 ◽  
Author(s):  
Claudio Toro-Serey ◽  
Sean M. Tobyne ◽  
Joseph T. McGuire
Keyword(s):  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Cognitive Functions ◽  
Fmri Data ◽  
Default Network ◽  
List Type ◽  
Individual Level ◽  
Human Connectome Project ◽  
Spectral Partitioning ◽  
The Individual

AbstractRegions of human medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC) are part of the default network (DN), and additionally are implicated in diverse cognitive functions ranging from autobiographical memory to subjective valuation. Our ability to interpret the apparent co-localization of task-related effects with DN-regions is constrained by a limited understanding of the individual-level heterogeneity in mPFC/PCC functional organization. Here we used cortical surface-based meta-analysis to identify a parcel in human PCC that was more strongly associated with the DN than with valuation effects. We then used resting-state fMRI data and a data-driven network analysis algorithm, spectral partitioning, to partition mPFC and PCC into “DN” and “non-DN” subdivisions in individual participants (n = 100 from the Human Connectome Project). The spectral partitioning algorithm identified individual-level cortical subdivisions that varied markedly across individuals, especially in mPFC, and were reliable across test/retest datasets. Our results point toward new strategies for assessing whether distinct cognitive functions engage common or distinct mPFC subregions at the individual level.HighlightsThe topography of Default Network cortical regions varies across individuals.A community detection algorithm, spectral partitioning, was applied to rs-fMRI data.The algorithm identified individualized Default Network regions in mPFC and PCC.Default Network topography varied across individuals in mPFC, moreso than in PCC.Overlap of task effects with DN regions should be assessed at the individual level.

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