scholarly journals Differential Structure of Hippocampal CA1 Pyramidal Neurons in the Human and Mouse

2019 ◽  
Author(s):  
Ruth Benavides-Piccione ◽  
Mamen Regalado-Reyes ◽  
Isabel Fernaud-Espinosa ◽  
Asta Kastanauskaite ◽  
Silvia Tapia-González ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Homologous Region ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 ◽  
Structural Differences ◽  
Species Specific ◽  
Human And Mouse ◽  
Shed Light

Abstract Pyramidal neurons are the most common cell type and are considered the main output neuron in most mammalian forebrain structures. In terms of function, differences in the structure of the dendrites of these neurons appear to be crucial in determining how neurons integrate information. To further shed light on the structure of the human pyramidal neurons we investigated the geometry of pyramidal cells in the human and mouse CA1 region—one of the most evolutionary conserved archicortical regions, which is critically involved in the formation, consolidation, and retrieval of memory. We aimed to assess to what extent neurons corresponding to a homologous region in different species have parallel morphologies. Over 100 intracellularly injected and 3D-reconstructed cells across both species revealed that dendritic and axonal morphologies of human cells are not only larger but also have structural differences, when compared to mouse. The results show that human CA1 pyramidal cells are not a stretched version of mouse CA1 cells. These results indicate that there are some morphological parameters of the pyramidal cells that are conserved, whereas others are species-specific.

scholarly journals Comparing basal dendrite branches in human and mouse hippocampal CA1 pyramidal neurons with Bayesian networks

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bojan Mihaljević ◽  
Pedro Larrañaga ◽  
Ruth Benavides-Piccione ◽  
Javier DeFelipe ◽  
Concha Bielza
Keyword(s):  
Bayesian Networks ◽  
Pyramidal Neurons ◽  
Graphical Representation ◽  
Data Set ◽  
Ca1 Region ◽  
Basal Dendrites ◽  
Hippocampal Ca1 ◽  
Dendritic Branches ◽  
Branch Type ◽  
Human And Mouse

Abstract Pyramidal neurons are the most common cell type in the cerebral cortex. Understanding how they differ between species is a key challenge in neuroscience. A recent study provided a unique set of human and mouse pyramidal neurons of the CA1 region of the hippocampus, and used it to compare the morphology of apical and basal dendritic branches of the two species. The study found inter-species differences in the magnitude of the morphometrics and similarities regarding their variation with respect to morphological determinants such as branch type and branch order. We use the same data set to perform additional comparisons of basal dendrites. In order to isolate the heterogeneity due to intrinsic differences between species from the heterogeneity due to differences in morphological determinants, we fit multivariate models over the morphometrics and the determinants. In particular, we use conditional linear Gaussian Bayesian networks, which provide a concise graphical representation of the independencies and correlations among the variables. We also extend the previous study by considering additional morphometrics and by formally testing whether a morphometric increases or decreases with the distance from the soma. This study introduces a multivariate methodology for inter-species comparison of morphology.

scholarly journals Ischemic Damage in Hippocampal CA1 is Dependent on Glutamate Release and Intact Innervation from CA3

1989 ◽  
Vol 9 (5) ◽  
pp. 629-639 ◽  
Author(s):  
H. Benveniste ◽  
M. B. Jørgensen ◽  
M. Sandberg ◽  
T. Christensen ◽  
H. Hagberg ◽  
...  
Keyword(s):  
Injection Site ◽  
Glutamate Release ◽  
Pyramidal Cells ◽  
Global Ischemia ◽  
Ischemic Damage ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Tissue ◽  
Hippocampal Ca1 ◽  
Transient Global Ischemia

The removal of glutamatergic afferents to CA1 by destruction of the CA3 region is known to protect CA1 pyramidal cells against 10 min of transient global ischemia. To investigate further the pathogenetic significance of glutamate, we measured the release of glutamate in intact and CA3-lesioned CA1 hippocampal tissue. In intact CA1 hippocampal tissue, glutamate increased sixfold during ischemia; in the CA3-lesioned CA1 region, however, glutamate only increased 1.4-fold during ischemia. To assess the neurotoxic potential of the ischemia-induced release of glutamate, we injected the same concentration of glutamate into the CA1 region as is released during ischemia in normal, CA3-lesioned, and ischemic CA1 tissue. We found that this particular concentration of glutamate was sufficient to destroy CA1 pyramids in the vicinity of the injection site in intact and CA3-lesioned CA1 tissue when administered during control (non-ischemic) conditions. In contrast, the same amount injected during ischemia in the CA3-lesioned CA1 region destroyed pyramidal cells in a widely distributed zone around the injection site in the CA1 region. It is concluded that the ischemia-induced damage of pyramidal cells in CA1 is dependent on glutamate release and intact innervation from CA3.

Comparable GABAergic Mechanisms of Hippocampal Seizurelike Activity in Posttetanic and Low-Mg2+ Conditions

2006 ◽  
Vol 95 (3) ◽  
pp. 2013-2019 ◽  
Author(s):  
Yoko Fujiwara-Tsukamoto ◽  
Yoshikazu Isomura ◽  
Masahiko Takada
Keyword(s):  
Seizure Activity ◽  
Extracellular Fluid ◽  
Pyramidal Cells ◽  
Gabaergic Interneurons ◽  
Tetanic Stimulation ◽  
Inhibitory Neurotransmitter ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 ◽  
Oscillatory Response

It is known that GABA is a major inhibitory neurotransmitter in mature mammalian brains, but the effect of this substance is sometimes converted into depolarizing or even excitatory when the postsynaptic Cl– concentration becomes high. Recently we have shown that seizurelike afterdischarge induced by tetanic stimulation in normal extracellular fluid (posttetanic afterdischarge) is mediated through GABAergic excitation in mature hippocampal CA1 pyramidal cells. In this study, we examined the possible contribution of similar depolarizing/excitatory GABAergic input to the CA1 pyramidal cells to the seizurelike afterdischarge induced in a low extracellular Mg2+ condition, another experimental model of epileptic seizure activity (low-Mg2+ afterdischarge). Perfusion of the GABAA antagonist bicuculline abolished the low-Mg2+ afterdischarge, but not the interictal-like activity, in most cases. Each oscillatory response during the low-Mg2+ afterdischarge was dependent on Cl– conductance and contained an F–-insensitive depolarizing component in the pyramidal cells, thus indicating that the afterdischarge response may be mediated through both GABAergic and nonGABAergic transmissions. In addition, local GABA application to the recorded cells revealed that GABA responses were indeed depolarizing during the low-Mg2+ afterdischarge. Furthermore, the GABAergic interneurons located in the strata pyramidale and oriens fired in oscillatory cycles more actively than those in other layers of the CA1 region. These results suggest that the depolarizing GABAergic input may facilitate oscillatory synchronization among the hippocampal CA1 pyramidal cells during the low-Mg2+ afterdischarge in a manner similar to the expression of the posttetanic afterdischarge.

scholarly journals Stratum Lacunosum-moleculare Interneurons of the Hippocampus Coordinate Memory Encoding and Retrieval

2021 ◽  
Author(s):  
Jun Guo ◽  
Heankel Cantu Oliveros ◽  
So Jung Oh ◽  
Bo Liang ◽  
Ying Li ◽  
...  
Keyword(s):  
Pyramidal Cells ◽  
Brain Regions ◽  
Cellular Level ◽  
Memory Encoding ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Stratum Lacunosum Moleculare ◽  
Encoding And Retrieval

Encoding and retrieval of memory are two processes serving distinct biological purposes but operating in highly overlapping brain circuits. It is unclear how the two processes are coordinated in the same brain regions, especially in the hippocampal CA1 region where the two processes converge at the cellular level. Here we find that the neuron-derived neurotrophic factor (NDNF)-positive interneurons at stratum lacunosum-moleculare (SLM) in CA1 play opposite roles in memory encoding and retrieval. These interneurons show high activities in learning and low activities in recall. Increasing their activity facilitates learning but impairs recall. They inhibit the entorhinal- but dis-inhibit the CA3- inputs to CA1 pyramidal cells and thereby either suppress or elevate CA1 pyramidal cells′ activity depending on animal′s behavioral states. Thus, by coordinating entorhinal- and CA3- dual inputs to CA1, these SLM interneurons are key to switching the hippocampus between encoding and retrieval modes.

Modeling Hippocampal CA1 Gabaergic Synapses of Audiogenic Rats

2020 ◽  
Vol 30 (05) ◽  
pp. 2050022
Author(s):  
Rodrigo F. O. Pena ◽  
Cesar Celis Ceballos ◽  
Júnia Lara De Deus ◽  
Antonio Carlos Roque ◽  
Norberto Garcia-Cairasco ◽  
...  
Keyword(s):  
Computational Model ◽  
Pyramidal Neurons ◽  
Temporal Dynamics ◽  
Pyramidal Cells ◽  
Homogeneous Population ◽  
Ca1 Pyramidal Cells ◽  
Physiological Properties ◽  
Hippocampal Ca1 ◽  
Gabaergic Synapses ◽  
Ca1 Pyramidal Neuron

Wistar Audiogenic Rats (WARs) are genetically susceptible to sound-induced seizures that start in the brainstem and, in response to repetitive stimulation, spread to limbic areas, such as hippocampus. Analysis of the distribution of interevent intervals of GABAergic inhibitory postsynaptic currents (IPSCs) in CA1 pyramidal cells showed a monoexponential trend in Wistar rats, suggestive of a homogeneous population of synapses, but a biexponential trend in WARs. Based on this, we hypothesize that there are two populations of GABAergic synaptic release sites in CA1 pyramidal neurons from WARs. To address this hypothesis, we used a well-established neuronal computational model of a CA1 pyramidal neuron previously developed to replicate physiological properties of these cells. Our simulations replicated the biexponential trend only when we decreased the release frequency of synaptic currents by a factor of six in at least 40% of distal synapses. Our results suggest that almost half of the GABAergic synapses of WARs have a drastically reduced spontaneous release frequency. The computational model was able to reproduce the temporal dynamics of GABAergic inhibition that could underlie susceptibility to the spread of seizures.

scholarly journals Postsynaptic and Spiking Activity of Pyramidal Cells, the Principal Neurons in the Rat Hippocampal CA1 Region, Does Not Control the Resultant BOLD Response: A Combined Electrophysiologic and fMRI Approach

2015 ◽  
Vol 35 (4) ◽  
pp. 565-575 ◽  
Author(s):  
Thomas Scherf ◽  
Frank Angenstein
Keyword(s):  
Pyramidal Cells ◽  
Bold Response ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Postsynaptic Activity ◽  
Hippocampal Ca1 ◽  
Bold Responses ◽  
Stimulation Of ◽  
Spiking Activity

The specific role of postsynaptic activity for the generation of a functional magnetic resonance imaging (fMRI) response was determined by a simultaneous measurement of generated field excitatory postsynaptic potentials (fEPSPs) and blood oxygen level-dependent (BOLD) response in the rat hippocampal CA1 region during electrical stimulation of the contralateral CA3 region. The stimulation electrode was placed either in the left CA3a/b or CA3c, causing the preferentially basal or apical dendrites of the pyramidal cells in the right CA1 to be activated. Consecutive stimulations with low-intensity stimulation trains (i.e., 16 pulses for 8 seconds) resulted in clear postsynaptic responses of CA1 pyramidal cells, but in no significant BOLD responses. In contrast, consecutive high-intensity stimulation trains resulted in stronger postsynaptic responses that came along with minor (during stimulation of the left CA3a/b) or substantial (during stimulation of the left CA3c) spiking activity of the CA1 pyramidal cells, and resulted in the generation of significant BOLD responses in the left and right hippocampus. Correlating the electrophysiologic parameters of CA1 pyramidal cell activity (fEPSP and spiking activity) with the resultant BOLD response revealed no positive correlation. Consequently, postsynaptic activity of pyramidal cells, the most abundant neurons in the CA1, is not directly linked to the measured BOLD response.

Distribution of Slow AHP Channels on Hippocampal CA1 Pyramidal Neurons

2000 ◽  
Vol 83 (3) ◽  
pp. 1756-1759 ◽  
Author(s):  
John M. Bekkers
Keyword(s):  
Action Potentials ◽  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Apical Dendrite ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Pyramidal Neurons ◽  
Basal Dendrites ◽  
Hippocampal Ca1 ◽  
Cell Current ◽  
Whole Cell Current

This work was designed to localize the Ca2+-activated K+ channels underlying the slow afterhyperpolarization (sAHP) in hippocampal CA1 pyramidal cells. Cell-attached patches on the proximal 100 μm of the apical dendrite contained K+ channels, but not sAHP channels, activated by backpropagating action potentials. Amputation of the apical dendrite ∼30 μm from the soma, while simultaneously recording the sAHP whole cell current at the soma, depressed the sAHP amplitude by only ∼30% compared with control. Somatic cell-attached and nucleated patches did not contain sAHP current. Amputation of the axon ≥20 μm from the soma had little effect on the amplitude of the sAHP recorded in cortical pyramidal cells. By this process of elimination, it is suggested that sAHP channels may be concentrated in the basal dendrites of CA1 pyramids.

Intracellular QX-314 inhibits calcium currents in hippocampal CA1 pyramidal neurons

1996 ◽  
Vol 76 (3) ◽  
pp. 2120-2124 ◽  
Author(s):  
M. J. Talbot ◽  
R. J. Sayer
Keyword(s):  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Calcium Currents ◽  
High Threshold ◽  
Chloride Salt ◽  
Ca1 Pyramidal Cells ◽  
Na Currents ◽  
Hippocampal Ca1 ◽  
And Control ◽  
In Cells

1. The effects of intracellular QX-314 on Ca2+ currents were examined in CA1 pyramidal cells acutely isolated from rat hippocampus. In neurons dialyzed with 10 mM QX-314 (bromide salt), the amplitude of the high-threshold Ca2+ current was on average 20% of that in control cells and the current-voltage relationships (I-Vs) were shifted in the positive voltage direction. 2. The positive shift in the I-Vs was due to the presence of intracellular Br-, because it was reproduced by 10 mM NaBr and was not present when the chloride salt of QX-314 was used. 3. Low-threshold (T-type) Ca2+ currents, at test voltages of -50 and -40 mV, were on average < 45% of control amplitude in cells containing 10 mM QX-314 (chloride salt) and < 10% of control amplitude in cells with 10 mM QX-314 (bromide salt). 4. In neurons dialyzed with 1 mM QX-314, high-threshold Ca2+ currents were still significantly different from control and Na+ currents were not completely blocked. 5. The proportions of high-threshold Ca2+ current blocked by omega-conotoxin GVIA, omega-agatoxin IVA, and nimodipine were similar in cells dialyzed with 10 mM QX-314 and control cells, indicating that the drug does not selectively inhibit any of the Ca2+ channel subtypes distinguished by these antagonists.

Increased Excitatory Synaptic Activity and Local Connectivity of Hippocampal CA1 Pyramidal Cells in Rats With Kainate-Induced Epilepsy

2004 ◽  
Vol 92 (3) ◽  
pp. 1366-1373 ◽  
Author(s):  
Li-Rong Shao ◽  
F. Edward Dudek
Keyword(s):  
Pyramidal Neurons ◽  
Flash Photolysis ◽  
Pyramidal Cells ◽  
Mean Amplitude ◽  
Synaptic Activity ◽  
Control Group ◽  
Ca1 Pyramidal Cells ◽  
Hippocampal Ca1 ◽  
Caged Glutamate ◽  
Ca1 Area

Formation of local excitatory circuits may contribute to epileptogenesis. We tested the hypothesis that epileptogenesis is associated with increased recurrent excitation in the hippocampal CA1 area of rats with kainate-induced epilepsy. Whole cell recordings were obtained during focal flash photolysis of caged glutamate, which served as a focal excitant to activate local pyramidal cells and to study possible connections between neurons. Kainate-treated rats with spontaneous seizures were studied months after status epilepticus and were compared with saline-injected control rats. Experiments were done in isolated CA1 minislices and in bicuculline to block GABAA receptors. Spontaneous excitatory postsynaptic currents (sEPSCs) were present in 42% of the CA1 pyramidal cells from controls and 62% from kainate-treated rats. The frequency of sEPSCs in the kainate group was significantly higher than that in the control group, but mean amplitude was not different. Flash photolysis of caged glutamate on the somatodendritic area of CA1 pyramidal neurons caused a burst of action potentials. Local excitatory connections between CA1 pyramidal cells were found in 4 of 48 neurons (8%) in slices from control animals, but in significantly more neurons (12 of 37; 32%) from rats with kainate-induced epilepsy exhibited interconnections ( P < 0.001). Photoactivation of glutamate on recorded CA1 pyramidal cells in the kainate group sometimes caused afterdischarges, but not in controls. The kainate-treated rats with pyramidal cells that responded to photostimulaltion with repetitive EPSCs appeared to have experienced more severe seizures. These data provide new electrophysiological evidence for the formation of recurrent excitatory circuits in the CA1 area of rats with kainate-induced epilepsy.

scholarly journals Stratum Lacunosum-moleculare Interneurons of the Hippocampus Coordinate Memory Encoding and Retrieval

2021 ◽  
Author(s):  
Jun Guo ◽  
Heankel Oliveros ◽  
So Jung Oh ◽  
Bo Liang ◽  
Ying Li ◽  
...  
Keyword(s):  
Pyramidal Cells ◽  
Brain Regions ◽  
Cellular Level ◽  
Memory Encoding ◽  
Ca1 Pyramidal Cells ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Stratum Lacunosum Moleculare ◽  
Encoding And Retrieval

Abstract Encoding and retrieval of memory are two processes serving distinct biological purposes but operating in highly overlapping brain circuits. It is unclear how the two processes are coordinated in the same brain regions, especially in the hippocampal CA1 region where the two processes converge at the cellular level. Here we find that the neuron-derived neurotrophic factor (NDNF)-positive interneurons at stratum lacunosum-moleculare (SLM) in CA1 play opposite roles in memory encoding and retrieval. These interneurons show high activities in learning and low activities in recall. Increasing their activity facilitates learning but impairs recall. They inhibit the entorhinal- but dis-inhibit the CA3- inputs to CA1 pyramidal cells and thereby either suppress or elevate CA1 pyramidal cells’ activity depending on animal’s behavioral states. Thus, by coordinating entorhinal- and CA3- dual inputs to CA1, these SLM interneurons are key to switching the hippocampus between encoding and retrieval modes.

Sign in / Sign up

Export Citation Format

Share Document