A Novel In Vitro Preparation: the Intact Hippocampal Formation

Khalilov, Ilgam; Esclapez, Monique; Medina, Igor; Aggoun, Djamila; Lämsä, Karri; Leinekugel, Xavier; Khazipov, Roustem; Ben‐Ari, Yehezkel

doi:10.1016/s0896-6273(00)80956-3

Cited by 138 publications

(148 citation statements)

References 30 publications

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“…Hippocampal transverse slices (thickness of 0.6 -0.7 mm) were cut with a VT 1000S vibroslicer (Leica, Nussloch, Germany) and kept in oxygenated (95% O 2 -5% CO 2 ) aCSF at room temperature (20 -22°C) at least 1 hr before use. Unusually thick hippocampal slices were used to preserve the advantages of the intact hippocampal preparation in vitro (Khalilov et al, 1997). There was no correlation between extracellularly recorded action potential frequency and electrode depth, indicating that, if the oxygen tension was lower in the center of our 700-m-thick slices, it did not affect neuronal or network excitability.…”

Section: Methodsmentioning

confidence: 99%

Excitatory Actions of Endogenously Released GABA Contribute to Initiation of Ictal Epileptiform Activity in the Developing Hippocampus

2003

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In the developing rat hippocampus, ictal epileptiform activity can be elicited easily in vitro during the first three postnatal weeks. Changes in neuronal ion transport during this time cause the effects of GABA A receptor (GABA A -R) activation to shift gradually from strongly depolarizing to hyperpolarizing. It is not known whether the depolarizing effects of GABA and the propensity for ictal activity are causally linked. A key question is whether the GABA-mediated depolarization is excitatory, which we defined operationally as being sufficient to trigger action potentials. We assessed the effect of endogenous GABA on ictal activity and neuronal firing rate in hippocampal slices from postnatal day 1 (P1) to P30. In extracellular recordings, there was a strong correlation between the postnatal age at which GABA A -R antagonists decreased action potential frequency (P23) and the age at which ictal activity could be induced by elevated potassium (P23). In addition, there was a strong correlation between the fraction of slices in which ictal activity was induced by elevated potassium concentrations and the fractional decrease in action potential firing when GABA A -Rs were blocked in the presence of ionotropic glutamate receptor antagonists. Finally, ictal activity induced by elevated potassium was blocked by the GABA A -R antagonists bicuculline and SR-95531 (gabazine) and increased in frequency and duration by GABA A -R agonists isoguvacine and muscimol. Thus, the propensity of the developing hippocampus for ictal activity is highly correlated with the effect of GABA on action potential probability and reversed by GABA A antagonists, indicating that GABA-mediated excitation is causally linked to ictal activity in this developmental window.

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Section: Methodsmentioning

confidence: 99%

Excitatory Actions of Endogenously Released GABA Contribute to Initiation of Ictal Epileptiform Activity in the Developing Hippocampus

2003

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“…In a chilled and perfused bath, the brain was cut into the left and right hemisphere, and the complete hippocampus, including the septum, was extracted from each hemisphere. This preparation maintains the whole 3D hippocampal architecture, preserving cellular and axonal integrity (32,33). Freshly extracted preparations were placed in a chamber and perfused with oxygenated (95% O 2 /5% CO 2 ) ACSF (126 mM NaCl, 3.5 mM KCl, 2 mM CaCl 2 , 1.3 mM MgCl 2 , 1.2 mM NaH 2 PO 4 , 26.2 mM NaHCO 3 , and 10 mM glucose).…”

mentioning

confidence: 99%

Bioelectronic neural pixel: Chemical stimulation and electrical sensing at the same site

Jönsson

Inal

Uguz

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

117

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Local control of neuronal activity is central to many therapeutic strategies aiming to treat neurological disorders. Arguably, the best solution would make use of endogenous highly localized and specialized regulatory mechanisms of neuronal activity, and an ideal therapeutic technology should sense activity and deliver endogenous molecules at the same site for the most efficient feedback regulation. Here, we address this challenge with an organic electronic multifunctional device that is capable of chemical stimulation and electrical sensing at the same site, at the single-cell scale. Conducting polymer electrodes recorded epileptiform discharges induced in mouse hippocampal preparation. The inhibitory neurotransmitter, γ-aminobutyric acid (GABA), was then actively delivered through the recording electrodes via organic electronic ion pump technology. GABA delivery stopped epileptiform activity, recorded simultaneously and colocally. This multifunctional “neural pixel” creates a range of opportunities, including implantable therapeutic devices with automated feedback, where locally recorded signals regulate local release of specific therapeutic agents.

Funding agencies:We thank Gaelle Rondeau and the staff of the clean room in Centre Microelectronique de Provence (CMP) for technical support during fabrication. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 602102 (EPITARGET) and Initiative of Excellence Aix-Marseilles project MIDOE (A_M-AAP-ID-13-24-130531-16.31-BERNARD-HLS). Funding was also provided by the Swedish Innovation Office (2010-00507), the Swedish Research Council (621-2011-3517), and the Knut and Alice Wallenberg Foundation (KAW Scholar, 2012.0302). The authors also thank the National Science Foundation Grant DMR-1105253 for partial support of this work, the French National Research Agency (ANR) through the project PolyProbe (ANR-13-BSV5-0019-01), Fondation pour la Recherche Medicale under Grant Agreements DBS20131128446 and ARF20150934124, Fondation de l'Avenir, the Onnesjo Foundation, the Region Provence-Alpes-Cote d'Azur, and Microvitae Technologies. J.R. and L.K. acknowledge support from Marie Curie Fellowships. The fabrication of the device was performed, in part, at CMP.

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“…In this study, long-lasting ictal discharges (30-250 s) could be induced by applying solutions containing the GABA A receptor antagonist bicuculline, the glutamate receptor agonist kainate, or high K + while only brief interictal activities were recorded in age-matched slices under similar conditions. In addition to allow measurement of intracellular changes in [Ca 2+ ] using confocal microscopy from groups of neurons loaded extracellularly with Fluo 3-AM, Khalilov et al (1997) demonstrated that electrical stimulation of the septum inhibited the firing of hippocampal CA3 stratum oriens interneurons; this finding thus confirmed the existence of GABAergic projections from the septum to hippocampal interneurons (Freund and Antal, 1988).…”

Section: Isolated Hippocampimentioning

confidence: 80%

“…This preparation has also allowed the demonstration that ictal discharges induced by bath application of kainic acid originate from the hippocampus and propagate to the septum, since they disappear in the septum following its surgical separation from the hippocampus (Khalilov et al, 1997). Finally, by employing field potential or dual whole-cell recordings from the two interconnected hippocampi it was shown that unilateral application of medium containing high Mg 2+ or tetrodotoxin blocked the propagation of the ictal discharge generated in the contralateral hippocampus by high extracellular [K + ].…”

Section: Isolated Hippocampimentioning

confidence: 99%

Models of drug-induced epileptiform synchronization in vitro

Avoli

Jefferys

2016

Journal of Neuroscience Methods

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Models of epileptiform activity in vitro have many advantages for recording and experimental manipulation. Neural tissues can be maintained in vitro for hours, and in neuronal or organotypic slice cultures for several weeks. A variety of drugs and other agents increase activity in these in vitro conditions, in many cases resulting in epileptiform activity, thus providing a direct model of symptomatic seizures. We review these preparations and the experimental manipulations used to induce epileptiform activity. The most common of drugs used are GABA A receptor antagonists and potassium channel blockers (notably 4-aminopyridine). Muscarinic agents also can induce epileptiform synchronization in vitro, and include potassium channel inhibition amongst their cellular actions. Manipulations of extracellular ions are reviewed in another paper in this special issue, as are ex vivo slices prepared from chronically epileptic animals and from people with epilepsy. More complex slices including extensive networks and/or several connected brain structures can provide insights into the dynamics of long range connections during epileptic activity. Visualization of slices also provides opportunities for identification of living neurons and for optical recording/stimulation and manipulation. Overall, the analysis of the epileptiform activity induced in brain tissue in vitro has played a major role in advancing our understanding of the cellular and network mechanisms of epileptiform synchronization, and it is expected to continue to do so in future.

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A Novel In Vitro Preparation: the Intact Hippocampal Formation

Cited by 138 publications

References 30 publications

Excitatory Actions of Endogenously Released GABA Contribute to Initiation of Ictal Epileptiform Activity in the Developing Hippocampus

Excitatory Actions of Endogenously Released GABA Contribute to Initiation of Ictal Epileptiform Activity in the Developing Hippocampus

Bioelectronic neural pixel: Chemical stimulation and electrical sensing at the same site

Models of drug-induced epileptiform synchronization in vitro

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