scholarly journals CA1 pyramidal cells organize an episode by segmented and ordered events

2019 ◽  
Author(s):  
Chen Sun ◽  
Wannan Yang ◽  
Jared Martin ◽  
Susumu Tonegawa
Keyword(s):  
Discrete Event ◽  
Pyramidal Cells ◽  
Spatial Code ◽  
Code Tracking ◽  
Ca1 Pyramidal Cells ◽  
Hippocampal Ca1 ◽  
Code Changes ◽  
The Brain ◽  
Prevailing View

ABSTRACTA prevailing view is that the brain represents episodic experience as the continuous moment to moment changes in the experience. Whether the brain also represents the same experience as a sequence of discretely segmented events, is unknown. Here, we report a hippocampal CA1 “chunking code”, tracking an episode as its discrete event subdivisions (“chunks”) and the sequential relationships between them. The chunking code is unaffected by unpredicted variations within the events, reflecting the code’s flexible nature by being organized around events as abstract units. The chunking code changes accordingly when relationships between events are disrupted or modified. The discrete chunking code and continuous spatial code are represented in the same cells, but in an orthogonal manner, and can be independently perturbed. Optogenetic inactivation of MEC inputs to CA1 disrupts the chunking but not spatial code. The chunking code may be fundamental for representing an episode, alongside codes tracking continuous changes.

Hippocampus Retains the Periodicity of Gamma Stimulation In Vivo

2002 ◽  
Vol 88 (5) ◽  
pp. 2349-2354 ◽  
Author(s):  
J. E. Mikkonen ◽  
T. Grönfors ◽  
J. J. Chrobak ◽  
M. Penttonen
Keyword(s):  
Information Acquisition ◽  
Pyramidal Cells ◽  
Gamma Oscillations ◽  
Short Term ◽  
Ca1 Pyramidal Cells ◽  
State Dependent ◽  
Hippocampal Ca1 ◽  
Oscillatory Rhythms ◽  
The Brain

Several behavioral state dependent oscillatory rhythms have been identified in the brain. Of these neuronal rhythms, gamma (20–70 Hz) oscillations are prominent in the activated brain and are associated with various behavioral functions ranging from sensory binding to memory. Hippocampal gamma oscillations represent a widely studied band of frequencies co-occurring with information acquisition. However, induction of specific gamma frequencies within the hippocampal neuronal network has not been satisfactorily established. Using both in vivo intracellular and extracellular recordings from anesthetized rats, we show that hippocampal CA1 pyramidal cells can discharge at frequencies determined by the preceding gamma stimulation, provided that the gamma is introduced in theta cycles, as occurs in vivo. The dynamic short-term alterations in the oscillatory discharge described in this paper may serve as a coding mechanism in cortical neuronal networks.

scholarly journals The Entorhinal Cortical Alvear Pathway Differentially Excites Pyramidal Cells and Interneuron Subtypes in Hippocampal CA1

2020 ◽  
Author(s):  
Karen A Bell ◽  
Rayne Delong ◽  
Priyodarshan Goswamee ◽  
A Rory McQuiston
Keyword(s):  
Brain Slices ◽  
Pyramidal Cells ◽  
Excitatory Input ◽  
Theta Burst Stimulation ◽  
Ca1 Pyramidal Cells ◽  
Whole Cell Patch Clamp ◽  
Hippocampal Ca1 ◽  
Physiological Impact ◽  
Theta Burst ◽  
Synaptic Responses

Abstract The entorhinal cortex alvear pathway is a major excitatory input to hippocampal CA1, yet nothing is known about its physiological impact. We investigated the alvear pathway projection and innervation of neurons in CA1 using optogenetics and whole cell patch clamp methods in transgenic mouse brain slices. Using this approach, we show that the medial entorhinal cortical alvear inputs onto CA1 pyramidal cells (PCs) and interneurons with cell bodies located in stratum oriens were monosynaptic, had low release probability, and were mediated by glutamate receptors. Optogenetic theta burst stimulation was unable to elicit suprathreshold activation of CA1 PCs but was capable of activating CA1 interneurons. However, different subtypes of interneurons were not equally affected. Higher burst action potential frequencies were observed in parvalbumin-expressing interneurons relative to vasoactive-intestinal peptide-expressing or a subset of oriens lacunosum-moleculare (O-LM) interneurons. Furthermore, alvear excitatory synaptic responses were observed in greater than 70% of PV and VIP interneurons and less than 20% of O-LM cells. Finally, greater than 50% of theta burst-driven inhibitory postsynaptic current amplitudes in CA1 PCs were inhibited by optogenetic suppression of PV interneurons. Therefore, our data suggest that the alvear pathway primarily affects hippocampal CA1 function through feedforward inhibition of select interneuron subtypes.

Modeling Research on Spatiotemporal Dynamics of the Hippocampus

1997 ◽  
Vol 07 (01) ◽  
pp. 187-198 ◽  
Author(s):  
Haijian Sun ◽  
Lin Liu ◽  
Chunhua Feng ◽  
Aike Guo
Keyword(s):  
Pyramidal Cells ◽  
Behavioral Pattern ◽  
Spatiotemporal Dynamics ◽  
Epileptic Focus ◽  
Power Law Distribution ◽  
Ca1 Pyramidal Cells ◽  
Self Organized ◽  
Hippocampal Ca1 ◽  
Self Organized Criticality ◽  
Neurological Insult

The spatiotemporal dynamics of the hippocampus is studied. We first propose a fractal algorithm to model the growth of hippocampal CA1 pyramidal cells, together with an avalanche model for information transmission. Then the optical records of an epileptic focus in the hippocampus are analyzed and simulated. These processes indicate that the hippocampus normally stays in self-organized criticality with a harmonious spatiotemporal behavioral pattern, that is, showing 1/f fluctuation and power law distribution. In case of a neurological insult, the hippocampal system may step into supercriticality and initiate epilepsy.

Distance-Dependent Ni2+-Sensitivity of Synaptic Plasticity in Apical Dendrites of Hippocampal CA1 Pyramidal Cells

2002 ◽  
Vol 87 (2) ◽  
pp. 1169-1174 ◽  
Author(s):  
Yoshikazu Isomura ◽  
Yoko Fujiwara-Tsukamoto ◽  
Michiko Imanishi ◽  
Atsushi Nambu ◽  
Masahiko Takada
Keyword(s):  
Calcium Influx ◽  
Critical Role ◽  
Field Potential ◽  
Pyramidal Cells ◽  
Long Term Potentiation ◽  
Apical Dendrite ◽  
Excitatory Postsynaptic Potential ◽  
Distal Dendrite ◽  
Ca1 Pyramidal Cells ◽  
Hippocampal Ca1

Low concentration of Ni2+, a T- and R-type voltage-dependent calcium channel (VDCC) blocker, is known to inhibit the induction of long-term potentiation (LTP) in the hippocampal CA1 pyramidal cells. These VDCCs are distributed more abundantly at the distal area of the apical dendrite than at the proximal dendritic area or soma. Therefore we investigated the relationship between the Ni2+-sensitivity of LTP induction and the synaptic location along the apical dendrite. Field potential recordings revealed that 25 μM Ni2+ hardly influenced LTP at the proximal dendritic area (50 μm distant from the somata). In contrast, the same concentration of Ni2+ inhibited the LTP induction mildly at the middle dendritic area (150 μm) and strongly at the distal dendritic area (250 μm). Ni2+ did not significantly affect either the synaptic transmission at the distal dendrite or the burst-firing ability at the soma. However, synaptically evoked population spikes recorded near the somata were slightly reduced by Ni2+ application, probably owing to occlusion of dendritic excitatory postsynaptic potential (EPSP) amplification. Even when the stimulating intensity was strengthened sufficiently to overcome such a reduction in spike generation during LTP induction, the magnitude of distal LTP was not significantly recovered from the Ni2+-dependent inhibition. These results suggest that Ni2+ may inhibit the induction of distal LTP directly by blocking calcium influx through T- and/or R-type VDCCs. The differentially distributed calcium channels may play a critical role in the induction of LTP at dendritic synapses of the hippocampal pyramidal cells.

Zn2+ Blocks the NMDA- and Ca2+-Triggered Postexposure Current I pe in Hippocampal Pyramidal Cells

1998 ◽  
Vol 79 (2) ◽  
pp. 1124-1126 ◽  
Author(s):  
Qiang X. Chen ◽  
Katherine L. Perkins ◽  
Robert K. S. Wong
Keyword(s):  
Divalent Cations ◽  
Pyramidal Cells ◽  
Cell Voltage ◽  
Continuous Growth ◽  
Ca1 Pyramidal Cells ◽  
Cation Current ◽  
Hippocampal Ca1 ◽  
Intracellular Ca ◽  
Hippocampal Pyramidal Cells

Chen, Qiang X., Katherine L. Perkins, and Robert K. S. Wong. Zn2+ blocks the NMDA- and Ca2+-triggered postexposure current I pe in hippocampal pyramidal cells. J. Neurophysiol. 79: 1124–1126, 1998. Whole cell voltage-clamp recordings from acutely isolated hippocampal CA1 pyramidal cells from adult guinea pigs were used to evaluate divalent cations as possible blockers of the postexposure current ( I pe). I pe is a cation current that is triggered by the rise in intracellular Ca2+ concentration that occurs after the application of a toxic level of N-methyl-d-aspartate (NMDA). Once triggered, I pe continues to grow until death of the neuron occurs. I pe may be a critical link between transient NMDA exposure and cell death. I pe was blocked by micromolar concentrations of Zn2+. The Zn2+ effect had an IC50 of 64 μM and saturated at 500 μM. Prolonged Zn2+ block of I pe revealed that the maintenance of a steady I pe is not dependent on I pe-mediated Ca2+ influx but that the continuous growth in I pe is dependent on I pe-mediated Ca2+ influx. The availability of an effective blocker of I pe should facilitate the investigation of the intracellular activation pathway of I pe and the role of I pe in neuronal death.

scholarly journals Sex and chronic stress alter delta opioid receptor distribution within rat hippocampal CA1 pyramidal cells following behavioral challenges

2020 ◽  
Vol 13 ◽  
pp. 100236
Author(s):  
Batsheva R. Rubin ◽  
Megan A. Johnson ◽  
Jared M. Berman ◽  
Ellen Goldstein ◽  
Vera Pertsovskaya ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Chronic Stress ◽  
Pyramidal Cells ◽  
Delta Opioid Receptor ◽  
Behavioral Challenges ◽  
Ca1 Pyramidal Cells ◽  
Hippocampal Ca1 ◽  
Receptor Distribution
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