Electroresponsiveness of medial entorhinal cortex layer III neurons in vitro

Neuroscience ◽  
1997 ◽  
Vol 81 (4) ◽  
pp. 937-950 ◽  
Author(s):  
C.T Dickson ◽  
A.R Mena ◽  
A Alonso
Keyword(s):  
Entorhinal Cortex ◽  
Medial Entorhinal Cortex

scholarly journals Cholinergic Modulation of the Resonance Properties of Stellate Cells in Layer II of Medial Entorhinal Cortex

2010 ◽  
Vol 104 (1) ◽  
pp. 258-270 ◽  
Author(s):  
James G. Heys ◽  
Lisa M. Giocomo ◽  
Michael E. Hasselmo
Keyword(s):  
Patch Clamp ◽  
Resonance Frequency ◽  
Entorhinal Cortex ◽  
Stellate Cells ◽  
Cholinergic Modulation ◽  
Medial Entorhinal Cortex ◽  
Whole Cell ◽  
Whole Cell Patch Clamp ◽  
Resonance Properties

In vitro whole cell patch-clamp recordings of stellate cells in layer II of medial entorhinal cortex show a subthreshold membrane potential resonance in response to a sinusoidal current injection of varying frequency. Physiological recordings from awake behaving animals show that neurons in layer II medial entorhinal cortex, termed “grid cells,” fire in a spatially selective manner such that each cell's multiple firing fields form a hexagonal grid. Both the spatial periodicity of the grid fields and the resonance frequency change systematically in neurons along the dorsal to ventral axis of medial entorhinal cortex. Previous work has also shown that grid field spacing and acetylcholine levels change as a function of the novelty to a particular environment. Using in vitro whole cell patch-clamp recordings, our study shows that both resonance frequency and resonance strength vary as a function of cholinergic modulation. Furthermore, our data suggest that these changes in resonance properties are mediated through modulation of h-current and m-current.

Carbachol Induces Fast Oscillations in the Medial but not in the Lateral Entorhinal Cortex of the Isolated Guinea Pig Brain

1999 ◽  
Vol 82 (5) ◽  
pp. 2441-2450 ◽  
Author(s):  
Solange van der Linden ◽  
Ferruccio Panzica ◽  
Marco de Curtis
Keyword(s):  
Guinea Pig ◽  
Entorhinal Cortex ◽  
Gamma Oscillations ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Medial Entorhinal Cortex ◽  
Arterial Perfusion ◽  
Fast Oscillations ◽  
Guinea Pig Brain

Fast oscillations at 25–80 Hz (gamma activity) have been proposed to play a role in attention-related mechanisms and synaptic plasticity in cortical structures. Recently, it has been demonstrated that the preservation of the entorhinal cortex is necessary to maintain gamma oscillations in the hippocampus. Because gamma activity can be reproduced in vitro by cholinergic activation, this study examined the characteristics of gamma oscillations induced by arterial perfusion or local intracortical injections of carbachol in the entorhinal cortex of the in vitro isolated guinea pig brain preparation. Shortly after carbachol administration, fast oscillatory activity at 25.2–28.2 Hz was observed in the medial but not in the lateral entorhinal cortex. Such activity was transiently associated with oscillations in the theta range that showed a variable pattern of distribution in the entorhinal cortex. No oscillatory activity was observed when carbachol was injected in the lateral entorhinal cortex. Gamma activity in the medial entorhinal cortex showed a phase reversal at 200–400 μm, had maximal amplitude at 400–500 μm depth, and was abolished by arterial perfusion of atropine (5 μM). Local carbachol application in the medial entorhinal cortex induced gamma oscillations in the hippocampus, whereas no oscillations were observed in the amygdala and in the piriform, periamygdaloid, and perirhinal cortices ipsilateral and contralateral to the carbachol injection. Hippocampal oscillations had higher frequency than the gamma activity recorded in the entorhinal cortex, suggesting the presence of independent generators in the two structures. The selective ability of the medial but not the lateral entorhinal cortex to generate gamma activity in response to cholinergic activation suggests a differential mode of signal processing in entorhinal cortex subregions.

Synaptic and intrinsic responses of medical entorhinal cortical cells in normal and magnesium-free medium in vitro

1988 ◽  
Vol 59 (5) ◽  
pp. 1476-1496 ◽  
Author(s):  
R. S. Jones ◽  
U. Heinemann
Keyword(s):  
Entorhinal Cortex ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Nmda Receptor Antagonist ◽  
Field Potentials ◽  
Cortical Cells ◽  
Medial Entorhinal Cortex ◽  
Membrane Hyperpolarization

1. Extracellular recordings were made from slices of hippocampus plus parahippocampal regions maintained in vitro. Field potentials, recorded in the entorhinal cortex after stimulation in the subiculum, resembled those observed in vivo. 2. Washout of magnesium from the slices resulted in paroxysmal events which resembled those occurring during sustained seizures in vivo. These events were greatest in amplitude and duration in layers IV/V of the medial entorhinal cortex and could occur both spontaneously and in response to subicular stimulation. Spontaneous seizure-like events were not prevented by severing the connections between the hippocampus and entorhinal cortex, but much smaller and shorter events occurring in the dentate gyrus were stopped by this manipulation. Both spontaneous and evoked paroxysmal events were blocked by perfusion with the N-methyl-D-aspartate (NMDA) receptor antagonist, DL-2-amino-5-phosphonovalerate (2-AP5). 3. Neurons in layers IV/V were characterized by intracellular recording. Injection of depolarizing current in most cells evoked a train of nondecrementing action potentials with only weak spike frequency accommodation and little or no posttrain after hyperpolarization. 4. A small number of cells displayed burst response when depolarized by positive current. The burst consisted of a slow depolarization with superimposed action potentials which decreased in amplitude and increased in duration during the discharge. The burst was terminated by a strong after hyperpolarization and thereafter, during prolonged current pulses a train of nondecrementing spikes occurred. The burst response remained if the cell was held at hyperpolarized levels but was inactivated by holding the cell at a depolarized level. 5. Depolarizing synaptic potentials could be evoked by stimulation in the subiculum. A delayed and prolonged depolarization clearly decremented with membrane hyperpolarization and, occasionally, increased with depolarization. 6. Washout of magnesium from the slices resulted in an enhancement of the late depolarization and a reversal of its voltage dependence. Eventually a single shock to the subiculum evoked a large all-or-none paroxysmal depolarization associated with a massive increase in membrane conductance. Similar events occurred spontaneously in all cells tested. The paroxysmal depolarizations, both spontaneous and evoked, were rapidly blocked by 2-AP5. 7. It is concluded that medial entorhinal cortical cells possess several intrinsic and synaptic properties which confer an extreme susceptibility to generation of sustained seizure activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential electroresponsiveness of stellate and pyramidal-like cells of medial entorhinal cortex layer II

1993 ◽  
Vol 70 (1) ◽  
pp. 128-143 ◽  
Author(s):  
A. Alonso ◽  
R. Klink
Keyword(s):  
Membrane Potential ◽  
Entorhinal Cortex ◽  
Morphological Characteristics ◽  
Oscillatory Activity ◽  
Inward Rectification ◽  
Projection Neurons ◽  
Medial Entorhinal Cortex ◽  
Mean Frequency ◽  
Subthreshold Oscillations

1. The electroresponsive properties of neurons from layer II of the rat medial entorhinal cortex (MEC) were studied by intracellular recording under current clamp in an in vitro brain slice preparation. From a total of 184 cells that fulfilled our criteria for recording stability, two groups of projection neurons were distinguished on the basis of their intrinsic biophysical properties and morphological characteristics (demonstrated by intracellular biocytin injection; n = 34). 2. Stellate cells (SCs) were the most abundant (69%). They were highly electroresponsive, and minimal changes (1-3 mV) of membrane potential generated an active response. Subthreshold depolarizing or hyperpolarizing current pulse injection always caused the membrane potential to attain an early peak and then sag to a lower level. Depolarization-induced "sags" were larger and determined early firing in all cells. The voltage-current relationship of SCs was markedly non-linear, demonstrating robust inward rectification in the hyperpolarizing and depolarizing range. 3. SCs generated persistent rhythmic subthreshold voltage oscillations on DC depolarization positive to -60 mV. The mean frequency of the oscillations was 8.6 Hz (theta range) at a membrane potential of approximately -55 mV, at which level occasional single spiking also occurred. At slightly more positive potentials, a striking 1- to 3-Hz repetitive bursting pattern emerged. This consisted of nonadapting trains of spikes ("clusters") interspersed with subthreshold oscillations that had a mean frequency of 21.7 Hz (beta range). 4. Nonstellate cells (39%; mostly pyramidal-like) displayed time-dependent inward rectification that was less pronounced than that of SCs, and minimal depolarization-induced sags. On threshold depolarization, firing was always preceded by a slowly rising ramp depolarization and thus occurred with a long delay. Inward rectification in the depolarizing range was very pronounced. However, non-SCs did not generate persistent rhythmic subthreshold oscillatory activity or spike clusters. 5. Of the electrophysiological parameters quantified, spike threshold, spike duration, depolarizing afterpotential amplitude and apparent membrane time constant demonstrated statistically significant differences between SCs and non-SCs. 6. The repetitive hiring properties in response to square current pulses of short duration (< 500 ms) were also different between SCs and non-SCs. First, most SCs displayed a bilinear frequency-current (f-I) relationship for only the first interspike interval, whereas most non-SCs displayed a bilinear relationship for all intervals. Second, SCs had a much steeper primary f-I slope for early intervals than non-SCs. Finally, SCs displayed more pronounced and faster spike frequency adaptation than non-SCs.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals How to build a grid cell

2014 ◽  
Vol 369 (1635) ◽  
pp. 20120520 ◽  
Author(s):  
Christoph Schmidt-Hieber ◽  
Michael Häusser
Keyword(s):  
Entorhinal Cortex ◽  
Action Potentials ◽  
Path Integration ◽  
Grid Cell ◽  
Medial Entorhinal Cortex ◽  
Synaptic Inputs ◽  
New Findings ◽  
Cell Firing

Neurons in the medial entorhinal cortex fire action potentials at regular spatial intervals, creating a striking grid-like pattern of spike rates spanning the whole environment of a navigating animal. This remarkable spatial code may represent a neural map for path integration. Recent advances using patch-clamp recordings from entorhinal cortex neurons in vitro and in vivo have revealed how the microcircuitry in the medial entorhinal cortex may contribute to grid cell firing patterns, and how grid cells may transform synaptic inputs into spike output during firing field crossings. These new findings provide key insights into the ingredients necessary to build a grid cell.

scholarly journals Spike afterpotentials shape the in-vivo burst activity of principal cells in medial entorhinal cortex

2019 ◽  
Author(s):  
Dóra É. Csordás ◽  
Caroline Fischer ◽  
Johannes Nagele ◽  
Martin Stemmler ◽  
Andreas V.M. Herz
Keyword(s):  
Entorhinal Cortex ◽  
High Frequency ◽  
Cell Group ◽  
Two Dimensional ◽  
Grid Cells ◽  
Spatial Coding ◽  
Medial Entorhinal Cortex ◽  
Whole Cell

AbstractPrincipal neurons in rodent medial entorhinal cortex (MEC) generate high-frequency bursts during natural behavior. While in vitro studies point to potential mechanisms that could support such burst sequences, it remains unclear whether these mechanisms are effective under in-vivo conditions. In this study, we focused on the membrane-potential dynamics immediately following action potentials, as measured in whole-cell recordings from male mice running in virtual corridors (Domnisoru et al., 2013). These afterpotentials consisted either of a hyperpolarization, an extended ramp-like shoulder, or a depolarization reminiscent of depolarizing afterpotentials (DAPs) recorded in vitro in MEC stellate and pyramidal neurons. Next, we correlated the afterpotentials with the cells’ propensity to fire bursts. All DAP cells with known location resided in Layer II, generated bursts, and their inter-spike intervals (ISIs) were typically between five and fifteen milliseconds. The ISI distributions of Layer-II cells without DAPs peaked sharply at around four milliseconds and varied only minimally across that group. This dichotomy in burst behavior is explained by cell-group-specific DAP dynamics. The same two groups of bursting neurons also emerged when we clustered extracellular spike-train autocorrelations measured in real two-dimensional arenas (Latuske et al., 2015). No difference in the spatial coding properties of the grid cells across all three groups was discernible. Layer III neurons were only sparsely bursting and had no DAPs. As various mechanisms for modulating the ion-channels underlying DAPs exist, our results suggest that the temporal features of MEC activity can be altered while maintaining the cells’ spatial tuning characteristics.Significance StatementDepolarizing afterpotentials (DAPs) are frequently observed in principal neurons from slice preparations of rodent medial entorhinal cortex (MEC), but their functional role in vivo is unknown. Analyzing whole-cell data from mice running on virtual tracks, we show that DAPs do occur during behavior. Cells with prominent DAPs are found in Layer II; their inter-spike intervals reflect DAP time-scales. In contrast, neither the rarely bursting cells in Layer III, nor the high-frequency bursters in Layer II, have a DAP. Extracellular recordings from mice exploring real two-dimensional arenas demonstrate that grid cells within these three groups have rather similar spatial coding properties. We conclude that DAPs shape the temporal but not the spatial response characteristics of principal neurons in MEC.Author contributionsAll authors designed research. DÉC, CF, and JN performed research and analyzed data (equal contribution). AVMH wrote and edited the paper with support from MS and the other authors.

scholarly journals Crossed Entorhino-Dentate Projections Form and Terminate With Correct Layer-Specificity in Organotypic Slice Cultures of the Mouse Hippocampus

2021 ◽  
Vol 15 ◽  
Author(s):  
Lars Hildebrandt-Einfeldt ◽  
Kenrick Yap ◽  
Mandy H. Paul ◽  
Carolin Stoffer ◽  
Nadine Zahn ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Granule Cells ◽  
Molecular Layer ◽  
Medial Entorhinal Cortex ◽  
Functional Connections ◽  
Mouse Hippocampus ◽  
Organotypic Slice Cultures ◽  
High Degree ◽  
Layer Specificity

The entorhino-dentate projection, i.e., the perforant pathway, terminates in a highly ordered and laminated fashion in the rodent dentate gyrus (DG): fibers arising from the medial entorhinal cortex (MEC) terminate in the middle molecular layer, whereas fibers arising from the lateral entorhinal cortex (LEC) terminate in the outer molecular layer of the DG. In rats and rabbits, a crossed entorhino-dentate projection exists, which originates from the entorhinal cortex (EC) and terminates in the contralateral DG. In contrast, in mice, such a crossed projection is reportedly absent. Using single and double mouse organotypic entorhino-hippocampal slice cultures, we studied the ipsi- and crossed entorhino-dentate projections. Viral tracing revealed that entorhino-dentate projections terminate with a high degree of lamina-specificity in single as well as in double cultures. Furthermore, in double cultures, entorhinal axons arising from one slice freely intermingled with entorhinal axons originating from the other slice. In single as well as in double cultures, entorhinal axons exhibited a correct topographical projection to the DG: medial entorhinal axons terminated in the middle and lateral entorhinal axons terminated in the outer molecular layer. Finally, entorhinal neurons were virally transduced with Channelrhodopsin2-YFP and stimulated with light, revealing functional connections between the EC and dentate granule cells. We conclude from our findings that entorhino-dentate projections form bilaterally in the mouse hippocampus in vitro and that the mouse DG provides a permissive environment for crossed entorhinal fibers.

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