Hippocampus of the Brain: Ultrastructure of Hippocampal Axo-somatic Synapses

Blackstad, Theodor W.; Flood, PR

doi:10.1038/198542a0

Cited by 78 publications

(17 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4). Excitatory and inhibitory synapses are differentially distributed on target neurons in the hippocampus and neocortex (Gray, 1959;Blackstad and Flood, 1963;Andersen et al, 1966). These different distributions of excitatory and inhibitory synapses have also been demonstrated in hippocampal cultures using antibodies against synaptophysin and GAD65 (Benson and Cohen, 1996;Benson and Tanaka, 1998).…”

Section: Distribution Of Glutamatergic and Gabaergic Synapses During mentioning

confidence: 99%

“…The densities of the VGluT1-and VGAT-labeled terminals were defined as the number of VGluT1-and VGAT-immunopositive punctae per MAP2-immunopositive area. The excitatory and inhibitory synaptic terminals were differentially distributed on their postsynaptic target cells in the hippocampus and neocortex (Gray, 1959;Blackstad and Flood, 1963;Andersen et al, 1966). We therefore determined the densities of both types of terminals on somata and dendrites separately.…”

Section: Quantitative Image Analysismentioning

confidence: 99%

See 1 more Smart Citation

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

2013

View full text Add to dashboard Cite

The aim of this study was to clarify the saturation processes of excitatory and inhibitory synapse densities during the long-term development of cultured neuronal networks. For this purpose, we performed a long-term culture of rat cortical cells for 35 days in vitro (DIV). During this culture period, we labeled glutamatergic and GABAergic synapses separately using antibodies against vesicular glutamate transporter 1 (VGluT1) and vesicular transporter of -aminobutyric acid (VGAT). The densities and distributions of both types of synaptic terminals were measured simultaneously. Observations and subsequent measurements of immunofluorescence demonstrated that the densities of both types of antibody-labeled terminals increased gradually from 7 to 21-28 DIV. The densities did not show a further increase at 35 DIV and tended to become saturated.Triple staining with VGluT1, VGAT, and microtubule-associated protein 2 (MAP2) enabled analysis of the distribution of both types of synapses, and revealed that the densities of the two types of synaptic terminals on somata were not significantly different, but that glutamatergic synapses predominated on the dendrites during long-term culture.However, some neurons did not fall within this distribution, suggesting differences in synapse distribution on target neurons. The electrical activity also showed an initial increase and subsequent saturation of the firing rate and synchronized burst rate during long-term culture, and the number of days of culture to saturation from the initial increase followed the same pattern under this culture condition.

show abstract

Section: Distribution Of Glutamatergic and Gabaergic Synapses During mentioning

confidence: 99%

Section: Quantitative Image Analysismentioning

confidence: 99%

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

2013

View full text Add to dashboard Cite

show abstract

“…However, the latency to onset of EPSPs was not different from latencies of granule cell EPSPs. Therefore, it is unclear at the present time whether the pyramidal-shaped cells arc feedforward or feedback interneurons, as has been hypothesized (Andersen ct al., 1963;Blackstad and Flood, 1963;Buzsáki and Eidelberg, 1981).…”

Section: Types Of Responsesmentioning

confidence: 99%

“…In addition, they make symmetric synapses on their postsynaptic targets (Ribak and Anderson, 1980). Historically, they have been associated with a basket-like plexus (Ramón y Cajal, 1911;Lorenté de Nó, 1934;Andersen et al, 1963;Blackstad and Flood, 1963). Therefore, it is likely that the pyramidal-shaped neurons play an important role in inhibition in the dentate gyrus.…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological diversity of pyramidal‐shaped neurons at the granule cell layer/hilus border of the rat dentate gyrus recorded in vitro

Scharfman

1995

Hippocampus

View full text Add to dashboard Cite

In the rat dentate gyrus, pyramidal-shaped cells located on the border of the granule cell layer and the hilus are one of the most common types of γ-aminobutyric acid (GABA)-immunoreactive neurons. This study describes their electrophysiological characteristics. Membrane properties, patterns of discharge, and synaptic responses were recorded intracellularly from these cells in hippocampal slices. Each cell was identified as pyramidal-shaped by injecting the marker Neurobiotin intracellularly (n = 17).In several respects the membrane properties of the sampled cells were similar to "fast-spiking" cells (putative inhibitory interneurons) that have been described in other areas of the hippocampus. For example, input resistance was high (mean 91.3 megohms), the membrane time constant was short (mean 7.7 ms), and there was a large afterhyperpolarization following a single action potential (mean 10.5 mV at resting potential). However, the action potentials of most pyramidalshaped cells were not as brief (mean 1.2 ms total duration) as those of most previously described fast-spiking cells. Many pyramidal-shaped neurons had strong spike frequency adaptation relative to other fast-spiking cells. Although these latter two characteristics were apparent in the majority of the sampled cells, there were exceptional pyramidal-shaped neurons with fast action potentials and weak adaptation, demonstrating the electrophysiological variability of pyramidal-shaped cells.Responses to outer molecular layer stimulation were composed primarily of excitatory postsynaptic potentials (EPSPs) rather than inhibitory postsynaptic potentials (IPSPs), and were usually small (EPSPs evoked at threshold were often less than 2 mV), and brief (less than 30 ms). There was variability, because in a few cells EPSPs evoked at threshold were much larger. However, regardless of EPSP amplitude, suprathreshold stimulation (up to 4 times the threshold stimulus strength) rarely evoked more than one action potential in any cell. The results suggest that stimulation of perforant path axons produces limited excitatory synaptic responses in pyramidal-shaped neurons. This may be one of the reasons why they are relatively resistant to prolonged perforant path stimulation.The pyramidal-shaped neurons located at the base of the granule cell layer have been associated historically with a basket plexus around granule cell somata, and have been called pyramidal "basket" cells. However, basket-like endings were rare and axon collaterals outside the granule cell layer were common. Many axon collaterals were as far from the granule cell layer as the outer molecular layer and the central hilus, and antidromic action potentials could be recorded in some

show abstract

“…(1) and (2) is a point model. This approximation is justified when inhibitory coupling is considered because inhibitory synapses are mainly positioned on cell somata [2,6,14]. The v-nullcline V ≡ {(v, u) such thatv = 0} is a cubic curve while the u-nullcline U ≡ {(v, u) such thatu = 0} is a sigmoid function.…”

Section: Model For a Single Neuronmentioning

confidence: 99%

Synchronization in two neurons: Results for a two-component dynamical model with time-delayed inhibition

Renversezs

1998

Physica D: Nonlinear Phenomena

View full text Add to dashboard Cite

We study synchronization in two neurons using two-dimensional neuronal models coupled through threshold delayed inhibition, acting for a fixed duration T . We explain the mechanism of synchronization between the two coupled units by means of phase-plane analysis. Using a piecewise linear approximation, we compute the firing times of two mutually coupled neurons, which allows a quantitative study of synchronization. The results are in good agreement, both quantitatively and qualitatively, with the numerical simulations of the full nonlinear coupled system describing the two neurons. We first show that, with simple inhibition, only phase-lagged synchronization can be achieved except for a particular set of T -values. We then show that coincidence synchronization can rapidly be achieved with an improved coupling model which takes into account the increase of membrane conductance during inhibition.

show abstract

Hippocampus of the Brain: Ultrastructure of Hippocampal Axo-somatic Synapses

Cited by 78 publications

References 3 publications

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

Measurement of saturation processes in glutamatergic and GABAergic synapse densities during long-term development of cultured rat cortical networks

Electrophysiological diversity of pyramidal‐shaped neurons at the granule cell layer/hilus border of the rat dentate gyrus recorded in vitro

Synchronization in two neurons: Results for a two-component dynamical model with time-delayed inhibition

Contact Info

Product

Resources

About