Spatial coding and physiological properties of hippocampal neurons in the Cornu Ammonis subregions

Hippocampus ◽  
2016 ◽  
Vol 26 (12) ◽  
pp. 1593-1607 ◽  
Author(s):  
Azahara Oliva ◽  
Antonio Fernández-Ruiz ◽  
György Buzsáki ◽  
Antal Berényi
Keyword(s):  
Hippocampal Neurons ◽  
Spatial Coding ◽  
Physiological Properties ◽  
Cornu Ammonis

scholarly journals Hippocampal neurons with stable excitatory connectivity become part of neuronal representations

PLoS Biology ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. e3000928 ◽  
Author(s):  
Tim P. Castello-Waldow ◽  
Ghabiba Weston ◽  
Alessandro F. Ulivi ◽  
Alireza Chenani ◽  
Yonatan Loewenstein ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Pyramidal Neurons ◽  
Time Window ◽  
Structural Connectivity ◽  
Time Lapse ◽  
Early Gene ◽  
Synaptic Connectivity ◽  
Time Duration ◽  
Hippocampal Ca1 ◽  
Cornu Ammonis

Experiences are represented in the brain by patterns of neuronal activity. Ensembles of neurons representing experience undergo activity-dependent plasticity and are important for learning and recall. They are thus considered cellular engrams of memory. Yet, the cellular events that bias neurons to become part of a neuronal representation are largely unknown. In rodents, turnover of structural connectivity has been proposed to underlie the turnover of neuronal representations and also to be a cellular mechanism defining the time duration for which memories are stored in the hippocampus. If these hypotheses are true, structural dynamics of connectivity should be involved in the formation of neuronal representations and concurrently important for learning and recall. To tackle these questions, we used deep-brain 2-photon (2P) time-lapse imaging in transgenic mice in which neurons expressing the Immediate Early Gene (IEG) Arc (activity-regulated cytoskeleton-associated protein) could be permanently labeled during a specific time window. This enabled us to investigate the dynamics of excitatory synaptic connectivity—using dendritic spines as proxies—of hippocampal CA1 (cornu ammonis 1) pyramidal neurons (PNs) becoming part of neuronal representations exploiting Arc as an indicator of being part of neuronal representations. We discovered that neurons that will prospectively express Arc have slower turnover of synaptic connectivity, thus suggesting that synaptic stability prior to experience can bias neurons to become part of representations or possibly engrams. We also found a negative correlation between stability of structural synaptic connectivity and the ability to recall features of a hippocampal-dependent memory, which suggests that faster structural turnover in hippocampal CA1 might be functional for memory.

scholarly journals Deuterated Glutamate-Mediated Neuronal Activity on Micro-Electrode Arrays

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 830
Author(s):  
Wataru Minoshima ◽  
Kyoko Masui ◽  
Tomomi Tani ◽  
Yasunori Nawa ◽  
Satoshi Fujita ◽  
...  
Keyword(s):  
Spontaneous Activity ◽  
Neuronal Activity ◽  
Hippocampal Neurons ◽  
Neuronal Networks ◽  
Microelectrode Array ◽  
Mammalian Brain ◽  
Electrode Arrays ◽  
Physiological Properties ◽  
Micro Electrode Arrays

The excitatory synaptic transmission is mediated by glutamate (GLU) in neuronal networks of the mammalian brain. In addition to the synaptic GLU, extra-synaptic GLU is known to modulate the neuronal activity. In neuronal networks, GLU uptake is an important role of neurons and glial cells for lowering the concentration of extracellular GLU and to avoid the excitotoxicity. Monitoring the spatial distribution of intracellular GLU is important to study the uptake of GLU, but the approach has been hampered by the absence of appropriate GLU analogs that report the localization of GLU. Deuterium-labeled glutamate (GLU-D) is a promising tracer for monitoring the intracellular concentration of glutamate, but physiological properties of GLU-D have not been studied. Here we study the effects of extracellular GLU-D for the neuronal activity by using primary cultured rat hippocampal neurons that form neuronal networks on microelectrode array. The frequency of firing in the spontaneous activity of neurons increased with the increasing concentration of extracellular GLU-D. The frequency of synchronized burst activity in neurons increased similarly as we observed in the spontaneous activity. These changes of the neuronal activity with extracellular GLU-D were suppressed by antagonists of glutamate receptors. These results suggest that GLU-D can be used as an analog of GLU with equivalent effects for facilitating the neuronal activity. We anticipate GLU-D developing as a promising analog of GLU for studying the dynamics of glutamate during neuronal activity.

scholarly journals Facilitation versus depression in cultured hippocampal neurons determined by targeting of Ca2+ channel Cavβ4 versus Cavβ2 subunits to synaptic terminals

2007 ◽  
Vol 178 (3) ◽  
pp. 489-502 ◽  
Author(s):  
Mian Xie ◽  
Xiang Li ◽  
Jing Han ◽  
Daniel L. Vogt ◽  
Silke Wittemann ◽  
...  
Keyword(s):  
Transmitter Release ◽  
Hippocampal Neurons ◽  
Presynaptic Terminal ◽  
Paired Pulse ◽  
Physiological Properties ◽  
Specific Manner ◽  
A Subunit ◽  
Synaptic Distribution ◽  
Ca2 Channels ◽  
Cultured Hippocampal Neurons

Ca2+ channel β subunits determine the transport and physiological properties of high voltage–activated Ca2+ channel complexes. Our analysis of the distribution of the Cavβ subunit family members in hippocampal neurons correlates their synaptic distribution with their involvement in transmitter release. We find that exogenously expressed Cavβ4b and Cavβ2a subunits distribute in clusters and localize to synapses, whereas Cavβ1b and Cavβ3 are homogenously distributed. According to their localization, Cavβ2a and Cavβ4b subunits modulate the synaptic plasticity of autaptic hippocampal neurons (i.e., Cavβ2a induces depression, whereas Cavβ4b induces paired-pulse facilitation [PPF] followed by synaptic depression during longer stimuli trains). The induction of PPF by Cavβ4b correlates with a reduction in the release probability and cooperativity of the transmitter release. These results suggest that Cavβ subunits determine the gating properties of the presynaptic Ca2+ channels within the presynaptic terminal in a subunit-specific manner and may be involved in organization of the Ca2+ channel relative to the release machinery.

scholarly journals Dynamic control of hippocampal spatial coding resolution by local visual cues

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Romain Bourboulou ◽  
Geoffrey Marti ◽  
François-Xavier Michon ◽  
Elissa El Feghaly ◽  
Morgane Nouguier ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Visual Cues ◽  
Large Scale ◽  
Dynamic Control ◽  
Local Features ◽  
Temporal Coding ◽  
Spatial Coding ◽  
3D Objects ◽  
Phase Precession ◽  
Fast Adaptation

The ability to flexibly navigate an environment relies on a hippocampal-dependent cognitive map. External space can be internally mapped at different spatial resolutions. However, whether hippocampal spatial coding resolution can rapidly adapt to local features of an environment remains unclear. To explore this possibility, we recorded the firing of hippocampal neurons in mice navigating virtual reality environments, embedding or not local visual cues (virtual 3D objects) in specific locations. Virtual objects enhanced spatial coding resolution in their vicinity with a higher proportion of place cells, smaller place fields, increased spatial selectivity and stability. This effect was highly dynamic upon objects manipulations. Objects also improved temporal coding resolution through improved theta phase precession and theta timescale spike coordination. We propose that the fast adaptation of hippocampal spatial coding resolution to local features of an environment could be relevant for large-scale navigation.

scholarly journals Acute MPTP Treatment Impairs Dendritic Spine Density in the Mouse Hippocampus

2021 ◽  
Vol 11 (7) ◽  
pp. 833
Author(s):  
Poornima D. E. Weerasinghe-Mudiyanselage ◽  
Mary Jasmin Ang ◽  
Mai Wada ◽  
Sung-Ho Kim ◽  
Taekyun Shin ◽  
...  
Keyword(s):  
Mouse Model ◽  
Hippocampal Neurons ◽  
Late Phase ◽  
Spine Density ◽  
Branch Points ◽  
Synaptic Structure ◽  
Mouse Hippocampus ◽  
Cornu Ammonis ◽  
Mptp Treatment ◽  
Dendritic Complexity

Among the animal models of Parkinson’s disease (PD), the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model has shown both dopaminergic (DA) damage and related motor control defects, as observed in patients with PD. Recent studies have suggested that the DA system interacts with the synaptic plasticity of the hippocampus in PD. However, little is known about how alterations in the hippocampal structural plasticity are affected by the DA damage in MPTP-lesioned models. In the present study, we investigated alterations in dendritic complexity and spine density in the mouse hippocampus following acute MPTP treatment (22 mg/kg, intraperitoneally, four times/day, 2-h intervals). We confirmed that acute MPTP treatment significantly decreased initial motor function and persistently reduced the number of tyrosine hydroxylase-positive DA neurons in the substantia nigra. Golgi staining showed that acute MPTP treatment significantly reduced the spine density of neuronal dendrites in the cornu ammonis 1 (CA1) apical/basal and dentate gyrus (DG) subregions of the mouse hippocampus at 8 and 16 days after treatment, although it did not affect dendritic complexity (e.g., number of crossing dendrites, total dendritic length, and branch points per neuron) in both CA1 and DG subregions at all time points after treatment. Therefore, the present study provides anatomical evidence that acute MPTP treatment affects synaptic structure in the hippocampus during the late phase after acute MPTP treatment in mice, independent of any changes in the dendritic arborization of hippocampal neurons. These findings offer data for the ability of the acute MPTP-lesioned mouse model to replicate the non-nigrostriatal lesions of clinical PD.

scholarly journals Neural circuit dynamics of drug-context associative learning in the hippocampus

2021 ◽  
Author(s):  
Yanjun Sun ◽  
Lisa M Giocomo
Keyword(s):  
Hippocampal Neurons ◽  
Drugs Of Abuse ◽  
Neural Circuit ◽  
Spatial Coding ◽  
Drug Induced ◽  
Drug Seeking ◽  
Neural Representations ◽  
Seeking Behavior ◽  
Preference Task ◽  
Induced Changes

AbstractThe environmental context associated with previous drug consumption serves as a potent trigger for relapse to drug use. The mechanism by which existing neural representations of context are modified to incorporate information associated with a given drug however, remains unknown. Using longitudinal calcium imaging in freely behaving mice, we reveal that drug-context associations for psychostimulants and opioids are encoded in a subset of hippocampal neurons. In these neurons, drug context pairing in a conditioned place preference task weakened their spatial coding for the nondrug-paired context, with drug-induced changes to spatial coding predictive of drug-seeking behavior. Furthermore, the dissociative drug ketamine blocked both the drug-induced changes to hippocampal coding and corresponding drug-seeking behavior. Together, this work reveals how drugs of abuse can alter the hippocampal circuit to encode drug-context associations and points to the hippocampus as a key node in the cognitive process of drug addiction and context-induced drug relapse.

scholarly journals The hippocampal engram maps experience but not place

Science ◽  
2018 ◽  
Vol 361 (6400) ◽  
pp. 392-397 ◽  
Author(s):  
Kazumasa Z. Tanaka ◽  
Hongshen He ◽  
Anupratap Tomar ◽  
Kazue Niisato ◽  
Arthur J. Y. Huang ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Memory Recall ◽  
Spatial Coding ◽  
Theta Frequency ◽  
Memory Content ◽  
Sparse Population ◽  
Episodic Memories ◽  
Context Specific ◽  
Memory Engram

Episodic memories are encoded by a sparse population of hippocampal neurons. In mice, optogenetic manipulation of this memory engram established that these neurons are indispensable and inducing for memory recall. However, little is known about their in vivo activity or precise role in memory. We found that during memory encoding, only a fraction of CA1 place cells function as engram neurons, distinguished by firing repetitive bursts paced at the theta frequency. During memory recall, these neurons remained highly context specific, yet demonstrated preferential remapping of their place fields. These data demonstrate a dissociation of precise spatial coding and contextual indexing by distinct hippocampal ensembles and suggest that the hippocampal engram serves as an index of memory content.

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.

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