Organization of excitatory and inhibitory local networks in the caudal nucleus of tractus solitarius of rats revealed in in vitro slice preparation

1996 ◽  
Vol 373 (3) ◽  
pp. 309-321 ◽  
Author(s):  
Yoshinori Kawai ◽  
Emiko Senba
Keyword(s):  
Slice Preparation ◽  
Local Networks

Size Does Matter: Generation of Intrinsic Network Rhythms in Thick Mouse Hippocampal Slices

2005 ◽  
Vol 93 (4) ◽  
pp. 2302-2317 ◽  
Author(s):  
Chiping Wu ◽  
Wah Ping Luk ◽  
Jesse Gillis ◽  
Frances Skinner ◽  
Liang Zhang
Keyword(s):  
In Vitro Model ◽  
Adult Mouse ◽  
Hippocampal Slices ◽  
Network Connectivity ◽  
Slice Preparation ◽  
Fundamental Properties ◽  
Mouse Hippocampus ◽  
Hippocampal Network ◽  
Vitro Model

Rodent hippocampal slices of ≤0.5 mm thickness have been widely used as a convenient in vitro model since the 1970s. However, spontaneous population rhythmic activities do not consistently occur in this preparation due to limited network connectivity. To overcome this limitation, we develop a novel slice preparation of 1 mm thickness from adult mouse hippocampus by separating dentate gyrus from CA3/CA1 areas but preserving dentate–CA3-CA1 connectivity. While superfused in vitro at 32 or 37°C, the thick slice exhibits robust spontaneous network rhythms of 1–4 Hz that originate from the CA3 area. Via assessing tissue O2, K+, pH, synaptic, and single-cell activities of superfused thick slices, we verify that these spontaneous rhythms are not a consequence of hypoxia and nonspecific experimental artifacts. We suggest that the thick slice contains a unitary circuitry sufficient to generate intrinsic hippocampal network rhythms and this preparation is suitable for exploring the fundamental properties and plasticity of a functionally defined hippocampal “lamella” in vitro.

The influence of postmortem delay on evoked hippocampal field potentials in the in vitro slice preparation

1991 ◽  
Vol 113 (3) ◽  
pp. 373-377 ◽  
Author(s):  
B.W. Leonard ◽  
C.A. Barnes ◽  
G. Rao ◽  
T. Heissenbuttel ◽  
B.L. McNaughton
Keyword(s):  
Field Potentials ◽  
Slice Preparation ◽  
Hippocampal Field

scholarly journals A MICROCALORIMETRIC STUDY OF TURTLE CORTICAL SLICES: INSIGHTS INTO BRAIN METABOLIC DEPRESSION

1994 ◽  
Vol 191 (1) ◽  
pp. 141-153 ◽  
Author(s):  
C Doll ◽  
P Hochachka ◽  
S Hand
Keyword(s):  
Cortical Neurons ◽  
Heat Dissipation ◽  
Energy Charge ◽  
Utilization Rate ◽  
Rapid Decline ◽  
Metabolic Depression ◽  
Slice Preparation ◽  
Cortical Slices

In previous papers, we have examined turtle cortical neurons in vitro for mechanisms of anoxic metabolic depression ('channel arrest' and changes in electrical parameters). Negative results prompted the current study with the aim of examining more closely the energy profile and metabolism of turtle cortical slices. Calorimetry is used to measure heat dissipation during normoxia and nitrogen perfusion (120 min) and the results are converted into an ATP utilization rate. These indicate that the control rate of ATP utilization (1.72 µmol ATP g-1 min-1) agrees closely with in vivo whole-brain metabolic measurements. Both nitrogen perfusion and pharmacologically induced anoxic (cyanide+N2) groups depressed heat dissipation considerably compared with the control value (nitrogen 37 %; pharmacological anoxia 49 %). The resulting ATP utilization estimates indicate metabolic depressions of 30 % (nitrogen) and 42 % (pharmacological anoxia). The slice preparation did not exhibit a change in any measured adenylate parameter for up to 120 min of anoxia or pharmacological anoxia. Significant changes did occur in [ADP], ATP/ADP ratio and energy charge after 240 min of exposure to anoxic conditions. These results support the idea that the turtle cortical slice preparation has a profound resistance to anoxia, with both nitrogen perfusion and pharmacological anoxia causing a rapid decline in heat dissipation and metabolism.

Patterns of excitatory and inhibitory synaptic transmission in the rat neostriatum as revealed by 4-AP

1994 ◽  
Vol 72 (5) ◽  
pp. 2246-2256 ◽  
Author(s):  
J. Flores-Hernandez ◽  
E. Galarraga ◽  
J. C. Pineda ◽  
J. Bargas
Keyword(s):  
High Amplitude ◽  
Slice Preparation ◽  
Action Potential Firing ◽  
Inhibitory Synaptic Transmission ◽  
Synaptic Potentials ◽  
Potential Firing ◽  
Fast Spiking ◽  
Gabaa Antagonist ◽  
Intrinsic Neurons

1. Synaptic potentials induced by 4-aminopyridine (4-AP) were recorded intracellularly from rat neostriatal neurons in an in vitro slice preparation. EC50 for this 4-AP action was approximately 120 microM. The threshold for activation of synaptic potentials was 5 microM. 2. 4-AP-induced synaptic potentials appeared stochastically. Most were blocked by 1 microM tetrodotoxin or 400 microM Cd2+. Therefore they reflect a release of neurotransmitters dependent on both Ca2+ entry to the terminals and action potential firing. 3. Bicuculline (BIC) (< or = 10 microM), a gamma-aminobuturic acid-A (GABAA) antagonist, blocked about half of the 4-AP-induced synaptic potentials. This suggests that intrinsic inhibitory connections within the neostriatum are activated by 4-AP administration. 4. 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; < or = 10 microM) plus D-2-amino-5-phosphonovaleric acid (D-APV; < or = 100 microM) blocked most of the BIC-resistant 4-AP-induced synaptic potentials. This suggests that 4-AP induced release of glutamate (GLU) from extrinsic glutamatergic afferents. As most glutamatergic afferents are extrinsic, these afferents then would be able to fire spikes and release transmitter for several hours after they are cut from their somata. 5. If CNQX plus D-APV were administered before BIC, neostriatal neurons responded in different ways. In one half of the neurons, all induced synaptic potentials were blocked. This suggests that most GABAergic intrinsic connections between neostriatal neurons are activated indirectly by 4-AP. 4-AP would first activate extrinsic glutamatergic afferents and these in turn would activate GABAergic intrinsic neurons and connections. 6. In the remaining half of the recorded neurons, administration of CNQX plus D-APV blocked most, but not all of the 4-AP-induced synaptic potentials. The synaptic potentials that remained had a characteristic pattern: they were high amplitude, rhythmic, bursts of synaptic potentials. They were blocked by BIC (5 microM) but not by mecamylamine (> 10 microM). This suggests that these bursts of synaptic potentials were GABAergic and generated by intrinsic neurons. Therefore these neurons would not innervate all neostriatal neurons equally but just a subset of them. 7. Records from an identified aspiny neostriatal interneuron, obtained from the same preparation, are shown. This interneuron fired in bursts and its morphologically and physiologically similar to the recently described, fast spiking, parvalbumin immunoreactive, GABAergic, aspiny interneuron is functional in the slice preparation.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Rhythmic Properties of Neurons in the Rostral Ventrolateral Medulla of the Rat In Vitro: Effects of Clonidine

2002 ◽  
Vol 88 (5) ◽  
pp. 2262-2279 ◽  
Author(s):  
Antonio R. Granata ◽  
Morton I. Cohen
Keyword(s):  
Interspike Interval ◽  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Type I ◽  
Slice Preparation ◽  
Different Populations ◽  
In Vitro Effects ◽  
Spike Firing

The rostral ventrolateral medulla (RVLM) is thought to be the main central site for generation of tonic sympathetic activity. In the rat in vitro slice preparation, we used intracellular recordings to identify different populations of neurons in the RVLM: 43 spontaneously active neurons with regular (R) or irregular (I) patterns of spike firing and 10 silent neurons. The degree of regularity was quantified by the coefficient of variation (CV = SD/mean) of interspike interval durations, as well as by the rhythmic properties of the spike autospectrum and autocorrelation. The distribution of CVs was clustered: R and I neurons were defined as those with CVs ≤12% ( n = 21) or >12% ( n = 22), respectively. The R-type and I-type neurons resemble the type II and type I neurons, respectively, which were previously characterized in the RVLM in vivo as barosensitive and bulbospinal. Both types may be important in generation of sympathetic tone. Clonidine (1–100 μM) was applied to 10 R-type neurons and 16 I-type neurons. The firing of 21/26 was depressed to the point of silence. However, 18/26 neurons were excited earlier in the perfusion. The later depression of firing occurred in both I and R neurons and in different cases was associated with either hyperpolarization or depolarization.

Synaptically Evoked GABA Transporter Currents in Neocortical Glia

2002 ◽  
Vol 88 (6) ◽  
pp. 2899-2908 ◽  
Author(s):  
Gregory A. Kinney ◽  
William J. Spain
Keyword(s):  
Synaptic Transmission ◽  
Time Course ◽  
Glutamate Transporter ◽  
Repetitive Stimulation ◽  
Slice Preparation ◽  
Gaba Transporter ◽  
Gaba Transporters ◽  
Decay Times ◽  
Slow Rise

The presence, magnitude, and time course of GABA transporter currents were investigated in electrophysiologically characterized neocortical astrocytes in an in vitro slice preparation. On stimulation with a bipolar-tungsten stimulating electrode placed nearby, the majority of cells tested displayed long-lasting GABA transporter currents using both single and repetitive stimulation protocols. Using subtype-specific GABA transporter antagonists, long-lasting GABA transporter currents were identified in neocortical astrocytes that originated from at least two subtypes of GABA transporters: GAT-1 and GAT-2/3. These transporter currents displayed slow rise times and long decay times, contrasting the time course observed for glutamate transporter currents, and are indicative of a long extracellular time course of GABA as well as a role for glial GABA transporters during synaptic transmission.

scholarly journals Genesis of gasping is independent of levels of serotonin in the Pet-1 knockout mouse

2009 ◽  
Vol 107 (3) ◽  
pp. 679-685 ◽  
Author(s):  
Walter M. St.-John ◽  
Aihua Li ◽  
J. C. Leiter
Keyword(s):  
Knockout Mice ◽  
Knockout Mouse ◽  
Critical Role ◽  
Genetic Defect ◽  
Rhythmic Activity ◽  
Ventrolateral Medulla ◽  
Sudden Infant ◽  
Slice Preparation ◽  
Serotonergic Neurons

Eupnea is normal breathing. If eupnea fails, as in severe hypoxia or ischemia, gasping is recruited. Gasping can serve as a powerful mechanism for autoresuscitation. A failure of autoresuscitation has been proposed as a basis of the sudden infant death syndrome. In an in vitro preparation, endogenous serotonin is reported to be essential for expression of gasping. Using an in situ preparation of the Pet-1 knockout mouse, we evaluated such a critical role for serotonin. In this mouse, the number of serotonergic neurons is reduced by 85–90% compared with animals without this homozygous genetic defect. Despite this reduction in the number of serotonergic neurons, phrenic discharge in eupnea and gasping of Pet-1 knockout mice was not different from that of wild-type mice. Indeed, gasping continued unabated, even after administration of methysergide, a blocker of many types of receptors for serotonin, to Pet-1 knockout mice. We conclude that serotonin is not critical for expression of gasping. The proposal for such a critical role, on the basis of observations in the in vitro slice preparation, may reflect the minimal functional neuronal tissue and neurotransmitters in this preparation, such that the role of any remaining neurotransmitters is magnified. Also, rhythmic activity of the in vitro slice preparation has been characterized as eupnea or gasping solely on the basis of activity of the hypoglossal nerve or massed neuronal activities of the ventrolateral medulla. The accuracy of this method of classification has not been established.

Effects of extracellular calcium on low frequency induced potentiation and habituation in the in vitro hippocampal slice preparation

1982 ◽  
Vol 60 (3) ◽  
pp. 266-275 ◽  
Author(s):  
R. W. Turner ◽  
J. J. Miller
Keyword(s):  
Evoked Potentials ◽  
Hippocampal Slice ◽  
Low Frequency ◽  
Extracellular Calcium ◽  
Population Spike ◽  
Slice Preparation ◽  
Short Term ◽  
High Calcium ◽  
Frequency Potentiation

The electrophysiological characteristics of frequency potentiation and habituation were investigated in two afferent systems of the in vitro hippocampal slice preparation. Low frequency stimulation (1 Hz) of the Schaffer collateral – commissural (Sch–comm) fibers results in a short-term potentiation of the amplitude and rate of rise of the EPSP and population spike responses recorded in the CA1 region. In contrast, 1-Hz stimulation of the perforant path (PP) evokes a short-term, habituation-like depression of the dentate granule cell EPSP and population spike. An inverse relationship was observed between stimulus intensity and the magnitude of frequency potentiation or habituation. Changes in afferent fiber volleys or general excitability of postsynaptic membranes did not contribute significantly to the development of either of these forms of short-term plasticity. Perfusion with a medium containing a high calcium – low magnesium concentration (4 mM Ca+2 and 1 mM Mg+2) produced a differential effect on CA1 and dentate evoked potentials. Following a 20-min exposure to this medium, the amplitude of CA1 potentials was increased while dentate responses were decreased. Frequency potentiation of CA1 responses and habituation of dentate responses were depressed or eliminated by the high calcium medium.The opposing influence of extracellular calcium on CA1 and dentate evoked potentials indicates a fundamental difference in the process of transmitter release in these systems, a characteristic that may contribute to the production of frequency potentiation and habituation.

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