scholarly journals A characterization of the electrophysiological, morphological and input domains of vasoactive intestinal peptide (VIP) interneurons in the medial entorhinal cortex (MEC)

2020 ◽  
Author(s):  
Saishree Badrinarayanan ◽  
Frédéric Manseau ◽  
Byung Kook Lim ◽  
Sylvain Williams ◽  
Mark P. Brandon
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Long Range ◽  
Entorhinal Cortex ◽  
Spatial Location ◽  
Inhibitory Neurons ◽  
Morphological Properties ◽  
Auditory Information ◽  
Medial Entorhinal Cortex ◽  
Whole Cell Patch Clamp

AbstractCircuit interactions within the medial entorhinal cortex (MEC) translate movement into a coherent code for spatial location. Entorhinal principal cells are subject to strong lateral inhibition, suggesting that a disinhibitory mechanism may drive their activation. Cortical Vasoactive Intestinal Peptide (VIP) expressing inhibitory neurons predominantly contact interneurons, providing a local disinhibitory mechanism. Here, we investigate the electrophysiological and morphological properties of VIP cells using in vitro whole-cell patch clamp recordings and use rabies-mediated circuit tracing to discover long-range inputs that may modulate this population in mice. We report physiological and morphological properties of VIP cells that differ across lamina and along the dorsal-ventral MEC axis. Furthermore, we reveal long-range inputs to VIP neurons from regions known to encode proprioceptive and auditory information, including the mesencephalic trigeminal nucleus and superior para-olivary nuclei, respectively. These results characterize the properties of VIP cells and reveal sensory modalities that could drive disinhibition in the MEC.

scholarly journals A Characterization of the Electrophysiological and Morphological Properties of Vasoactive Intestinal Peptide (VIP) Interneurons in the Medial Entorhinal Cortex (MEC)

2021 ◽  
Vol 15 ◽  
Author(s):  
Saishree Badrinarayanan ◽  
Frédéric Manseau ◽  
Sylvain Williams ◽  
Mark P. Brandon
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Entorhinal Cortex ◽  
Spatial Location ◽  
Inhibitory Neurons ◽  
Morphological Properties ◽  
Medial Entorhinal Cortex ◽  
Electrophysiological Properties ◽  
Whole Cell Patch Clamp

Circuit interactions within the medial entorhinal cortex (MEC) translate movement into a coherent code for spatial location. Entorhinal principal cells are subject to strong lateral inhibition, suggesting that a disinhibitory mechanism may drive their activation. Cortical Vasoactive Intestinal Peptide (VIP) expressing inhibitory neurons are known to contact other interneurons and excitatory cells and are thus capable of providing a local disinhibitory mechanism, yet little is known about this cell type in the MEC. To investigate the electrophysiological and morphological properties of VIP cells in the MEC, we use in vitro whole-cell patch-clamp recordings in VIPcre/tdTom mice. We report several gradients in electrophysiological properties of VIP cells that differ across laminae and along the dorsal-ventral MEC axis. We additionally show that VIP cells have distinct morphological features across laminae. Together, these results characterize the cellular and morphological properties of VIP cells in the MEC.

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)

scholarly journals Distance- and activity-dependent modulation of spike back-propagation in layer V pyramidal neurons of the medial entorhinal cortex

2011 ◽  
Vol 105 (3) ◽  
pp. 1372-1379 ◽  
Author(s):  
Sonia Gasparini
Keyword(s):  
Entorhinal Cortex ◽  
High Speed ◽  
Pyramidal Neurons ◽  
Back Propagation ◽  
Medial Entorhinal Cortex ◽  
Type K ◽  
Whole Cell Patch Clamp ◽  
Voltage Dependent ◽  
Layer V ◽  
Activity Dependent

Layer V principal neurons of the medial entorhinal cortex receive the main hippocampal output and relay processed information to the neocortex. Despite the fundamental role hypothesized for these neurons in memory replay and consolidation, their dendritic features are largely unknown. High-speed confocal and two-photon Ca2+ imaging coupled with somatic whole cell patch-clamp recordings were used to investigate spike back-propagation in these neurons. The Ca2+ transient associated with a single back-propagating action potential was considerably smaller at distal dendritic locations (>200 μm from the soma) compared with proximal ones. Perfusion of Ba2+ (150 μM) or 4-aminopyridine (2 mM) to block A-type K+ currents significantly increased the amplitude of the distal, but not proximal, Ca2+ transients, which is strong evidence for an increased density of these channels at distal dendritic locations. In addition, the Ca2+ transients decreased with each subsequent spike in a 20-Hz train; this activity-dependent decrease was also more prominent at more distal locations and was attenuated by the perfusion of the protein kinase C activator phorbol-di-acetate. These data are consistent with a phosphorylation-dependent control of back-propagation during trains of action potentials, attributable mainly to an increase in the time constant of recovery from voltage-dependent inactivation of dendritic Na+ channels. In summary, dendritic Na+ and A-type K+ channels control spike back-propagation in layer V entorhinal neurons. Because the activity of these channels is highly modulated, the extent of the dendritic Ca2+ influx is as well, with important functional implications for dendritic integration and associative synaptic plasticity.

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

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.

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