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.

Slow Periodic Events and Their Transition to Gamma Oscillations in the Entorhinal Cortex of the Isolated Guinea Pig Brain

2003 ◽  
Vol 90 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Clayton T. Dickson ◽  
Gerardo Biella ◽  
Marco de Curtis
Keyword(s):  
Membrane Potential ◽  
Guinea Pig ◽  
Entorhinal Cortex ◽  
Gamma Oscillations ◽  
Oscillatory Activity ◽  
Periodic Field ◽  
Slow Potential ◽  
Pig Brain ◽  
Guinea Pig Brain

Slow (<1 Hz) periodic activity is a distinctive discharge pattern observed in different cortical and sub-cortical structures during sleep and anesthesia. By performing field and cellular recordings, we demonstrated that slow periodic events (0.02–0.4 Hz) are spontaneously generated in the entorhinal cortex of the in vitro isolated whole brain of the guinea pig. These events were characterized by gradually developing runs of low-amplitude (50–300 μV), high-frequency (25–70 Hz) oscillations superimposed on a slow potential that lasted 1–3 s. Both slow and fast components showed a phase reversal in the superficial layers. In layer II-III entorhinal neurons, the slow periodic events correlated to a slowly developing depolarizing envelope capped by subthreshold membrane potential oscillations and action potential discharge. Slow periodic field events propagated tangentially across the entorhinal cortex and could be triggered by stimulation of superficial associative fibers, suggesting that they were generated by and propagated via network interactions in the superficial layers. Slow periodic events were reversibly abolished by muscarinic excitation elicited by carbachol (50 μM) that promoted intracellular membrane potential depolarization associated with continuous fast oscillatory activity in the gamma frequency range. These results suggest that, as proposed in vivo, activity changes in the entorhinal cortex of the in vitro isolated guinea-pig brain reflect different activation states that are under cholinergic control.

Functional Interactions Within the Parahippocampal Region Revealed by Voltage-Sensitive Dye Imaging in the Isolated Guinea Pig Brain

2010 ◽  
Vol 103 (2) ◽  
pp. 725-732 ◽  
Author(s):  
Gerardo Biella ◽  
Paolo Spaiardi ◽  
Mauro Toselli ◽  
Marco de Curtis ◽  
Vadym Gnatkovsky
Keyword(s):  
Guinea Pig ◽  
Inhibitory Control ◽  
Entorhinal Cortex ◽  
Perirhinal Cortex ◽  
Retrosplenial Cortex ◽  
Arterial Perfusion ◽  
Entorhinal Region ◽  
Pig Brain ◽  
Guinea Pig Brain

The massive transfer of information from the neocortex to the entorhinal cortex (and vice versa) is hindered by a powerful inhibitory control generated in the perirhinal cortex. In vivo and in vitro experiments performed in rodents and cats support this conclusion, further extended in the present study to the analysis of the interaction between the entorhinal cortex and other parahippocampal areas, such as the postrhinal and the retrosplenial cortices. The experiments were performed in the in vitro isolated guinea pig brain by a combined approach based on electrophysiological recordings and fast imaging of optical signals generated by voltage-sensitive dyes applied to the entire brain by arterial perfusion. Local stimuli delivered in different portions of the perirhinal, postrhinal, and retrosplenial cortex evoked local responses that did not propagate to the entorhinal cortex. Neither high- and low-frequency-patterned stimulation nor paired associative stimuli facilitated the propagation of activity to the entorhinal region. Similar stimulations performed during cholinergic neuromodulation with carbachol were also ineffective in overcoming the inhibitory network that controls propagation to the entorhinal cortex. The pharmacological inactivation of GABAergic transmission by local application of bicuculline (1 mM) in area 36 of the perirhinal cortex facilitated the longitudinal (rostrocaudal) propagation of activity into the perirhinal/postrhinal cortices but did not cause propagation into the entorhinal cortex. Bicuculline injection in both area 35 and medial entorhinal cortex released the inhibitory control and allowed the propagation of the neural activity to the entorhinal cortex. These results demonstrate that, as for the perirhinal-entorhinal reciprocal interactions, also the connections between the postrhinal/retrosplenial cortices and the entorhinal region are subject to a powerful inhibitory control.

High-frequency oscillations and seizure-like discharges in the entorhinal cortex of the in vitro isolated guinea pig brain

2017 ◽  
Vol 130 ◽  
pp. 21-26 ◽  
Author(s):  
Laura Uva ◽  
Davide Boido ◽  
Massimo Avoli ◽  
Marco de Curtis ◽  
Maxime Lévesque
Keyword(s):  
Guinea Pig ◽  
Entorhinal Cortex ◽  
High Frequency ◽  
High Frequency Oscillations ◽  
Pig Brain ◽  
Guinea Pig Brain

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 Gamma activity accelerates during prefrontal development

2020 ◽  
Author(s):  
Sebastian H. Bitzenhofer ◽  
Jastyn A. Pöpplau ◽  
Ileana L. Hanganu-Opatz
Keyword(s):  
Prefrontal Cortex ◽  
Pyramidal Neurons ◽  
Temporal Dynamics ◽  
Rhythmic Activity ◽  
Gamma Oscillations ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Gamma Frequency ◽  
Gamma Rhythms ◽  
Fast Oscillations

AbstractGamma oscillations are a prominent activity pattern in the cerebral cortex. While gamma rhythms have been extensively studied in the adult prefrontal cortex in the context of cognitive (dys)functions, little is known about their development. We addressed this issue by using extracellular recordings and optogenetic stimulations in mice across postnatal development. We show that fast rhythmic activity in the prefrontal cortex becomes prominent during the second postnatal week. While initially at about 15 Hz, fast oscillatory activity progressively accelerates with age and stabilizes within gamma frequency range (30-80 Hz) during the fourth postnatal week. Activation of layer 2/3 pyramidal neurons drives fast oscillations throughout development, yet the acceleration of their frequency follows similar temporal dynamics as the maturation of fast-spiking interneurons. These findings uncover the development of prefrontal gamma activity and provide a framework to examine the origin of abnormal gamma activity in neurodevelopmental disorders.

scholarly journals Gamma activity accelerates during prefrontal development

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Sebastian H Bitzenhofer ◽  
Jastyn A Pöpplau ◽  
Ileana Hanganu-Opatz
Keyword(s):  
Prefrontal Cortex ◽  
Pyramidal Neurons ◽  
Temporal Dynamics ◽  
Rhythmic Activity ◽  
Gamma Oscillations ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Gamma Frequency ◽  
Gamma Rhythms ◽  
Fast Oscillations

Gamma oscillations are a prominent activity pattern in the cerebral cortex. While gamma rhythms have been extensively studied in the adult prefrontal cortex in the context of cognitive (dys)functions, little is known about their development. We addressed this issue by using extracellular recordings and optogenetic stimulations in mice across postnatal development. We show that fast rhythmic activity in the prefrontal cortex becomes prominent during the second postnatal week. While initially at about 15 Hz, fast oscillatory activity progressively accelerates with age and stabilizes within gamma frequency range (30–80 Hz) during the fourth postnatal week. Activation of layer 2/3 pyramidal neurons drives fast oscillations throughout development, yet the acceleration of their frequency follows similar temporal dynamics as the maturation of fast-spiking interneurons. These findings uncover the development of prefrontal gamma activity and provide a framework to examine the origin of abnormal gamma activity in neurodevelopmental disorders.

Changes in action potential features during focal seizure discharges in the entorhinal cortex of the in vitro isolated guinea pig brain

2011 ◽  
Vol 106 (3) ◽  
pp. 1411-1423 ◽  
Author(s):  
Federica Trombin ◽  
Vadym Gnatkovsky ◽  
Marco de Curtis
Keyword(s):  
Guinea Pig ◽  
Action Potential ◽  
Entorhinal Cortex ◽  
Temporal Lobe ◽  
Action Potentials ◽  
Extracellular Potassium ◽  
Pig Brain ◽  
Temporal Lobe Seizures ◽  
Guinea Pig Brain

Temporal lobe seizures in humans correlate with stereotyped electrophysiological patterns that can be reproduced in animal models to study the cellular and network changes responsible for ictogenesis. Seizure-like discharges that mimic seizure patterns in humans were induced in the entorhinal cortex of the in vitro isolated guinea pig brain by 3-min arterial applications of the GABAA receptor antagonist bicuculline. The onset of seizure is characterized by a paradoxical interruption of firing for several seconds in principal neurons coupled with both enhanced interneuronal firing and increased extracellular potassium ( Gnatkovsky et al. 2008 ). The evolution of action potential features from firing break to excessive and synchronous activity associated with the progression of seizure itself is analyzed here. We utilized phase plot analysis to characterize action potential features of entorhinal cortex neurons in different phases of a seizure. Compared with preictal action potentials, resumed spikes in layer II–III neurons ( n = 17) during the early phase of the seizure-like discharge displayed 1) depolarized threshold, 2) lower peak amplitude, 3) depolarized voltage of repolarization and 4) decelerated depolarizing phase, and 5) spike doublettes. Action potentials in deep-layer principal cells ( n = 8) during seizure did not show the marked feature changes observed in superficial layer neurons. Action potential reappearance correlated with an increase in extracellular potassium. High-threshold, slow-action potentials similar to those observed in the irregular firing phase of a seizure were reproduced in layer II–III neurons by direct cortical application of a highly concentrated potassium solution (12–24 mM). We propose that the generation of possibly nonsomatic action potentials by increased extracellular potassium represents a crucial step toward reestablish firing after an initial depression in an acute model of temporal lobe seizures. Resumed firing reengages principal neurons into seizure discharge and promotes the transition toward the synchronized burst firing that characterizes the late phase of a seizure.

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