Separation of neuronal sites of driver potential and impulse generation by ligaturing in the cardiac ganglion of the lobster,Homarus americanus

Tazaki, Kenro; Cooke, Ian M.

doi:10.1007/bf00623908

Cited by 35 publications

(30 citation statements)

References 30 publications

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“…The motor neurons are all individually identifiable, and due to their distributed nature within the ganglion (Fig. 1), we can perform pharmacological manipulations on one or multiple motor neurons, either in isolation or in the intact, functional network (Tazaki and Cooke, 1983a;Cooke, 2002). The underlying burst potentials of the LCs represent functional output at the motor neuron level, and our preliminary modeling studies show how the simplicity of this model system can be used to study functional implications of the relationships between mRNAs and ionic conductances on cellular output Franklin et al, 2010).…”

Section: Resultsmentioning

confidence: 99%

Rapid Homeostatic Plasticity of Intrinsic Excitability in a Central Pattern Generator Network Stabilizes Functional Neural Network Output

Ransdell¹,

Nair²,

Schulz³

2012

Journal of Neuroscience

104

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Neurons and networks undergo a process of homeostatic plasticity that stabilizes output by integrating activity levels with network and cellular properties to counter longer-term perturbations. Here we describe a rapid compensatory interaction among a pair of potassium currents, I A and I KCa , that stabilizes both intrinsic excitability and network function in the cardiac ganglion of the crab, Cancer borealis. We determined that mRNA levels in single identified neurons for the channels which encode I A and I KCa are positively correlated, yet the ionic currents themselves are negatively correlated, across a population of motor neurons. We then determined that these currents are functionally coupled; decreasing levels of either current within a neuron causes a rapid increase in the other. This functional interdependence results in homeostatic stabilization of both the individual neuronal and the network output. Furthermore, these compensatory increases are mechanistically independent, suggesting robustness in the maintenance of neural network output that is critical for survival. Together, we generate a complete model for homeostatic plasticity from mRNA to network output where rapid posttranslational compensatory mechanisms acting on a reservoir of channels proteins regulated at the level of gene expression provide homeostatic stabilization of both cellular and network activity.

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Section: Resultsmentioning

confidence: 99%

Rapid Homeostatic Plasticity of Intrinsic Excitability in a Central Pattern Generator Network Stabilizes Functional Neural Network Output

Ransdell¹,

Nair²,

Schulz³

2012

Journal of Neuroscience

104

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“…In some experiments, after a brief recording period to insure normal ganglionic function, a ligature of fine silk was tied tightly around the ganglionic trunk, at a location which varied depending on the particular experiment. This procedure functionally isolates the two ends of the ganglion (Tazaki and Cooke 1983a;Miller et al 1984). The electrical activity was monitored on either side of the ligature with 2 microelectrodes.…”

Section: Methodsmentioning

confidence: 98%

Endogenous burst-organizing potentials in two classes of neurons in the lobster cardiac ganglion respond differently to alterations in divalent ion concentration

Berlind

1985

J. Comp. Physiol.

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Summary. 1. Crustacean cardiac ganglion neurons generate endogenous burst-organizing potentials termed 'driver potentials'. In the five motorneurons ('large cells') in the system these are slow local potentials with the depolarizing current carried by calcium ions. The existence of similar endogenous potentials in the second class of neurons in the ganglion, the four small 'pacemaker' cells, has been postulated primarily on the basis of indirect evidence. The results presented here show that burst-generating mechanisms in the pacemaker neurons and motorneurons respond differently to alterations in the ionic content of the medium, and suggest that driver potentials have different ionic bases in the two cell types. (Homarus americanus) cardiac ganglia persists in altered form in salines containing high levels of manganese (Fig. 1) or reduced calcium (Figs. 3, 4). Both of these ionic alterations suppress driver potentials generated by the motorneurons (Fig. 2). Bursts generated in low-calcium salines were of very long duration. Bursting in isolated lobster3. In low-calcium salines the long-duration bursts resulted from prolonged and intensified discharge of the small pacemaker neurons; motorneuron activity was suppressed as would be predicted from blockade of the large cell driver potentials. These conclusions derive from the use of ligatured preparations, in which a large cell group was functionally isolated from the rest of the ganglion (Fig. 5); from two-pool preparations in which the two classes of cells were perfused independently in different ionic media (Fig. 6); and from ganglia in which one or the other cell type was silenced by selective application of tetrodotoxin (Figs. 7, 8).Abbreviations: DP driver potential; pln posterior lateral nerve; TTX tetrodotoxin; TEA tetraethylammonium 4. These experiments support the idea that driver potentials in the motorneurons are primarily based on inflow of calcium ions, but that a significant proportion of the inward current responsible for the driver potentials in the small pacemaker neurons is carried by an ion other than calcium.5. The results support current models for the roles of endogenous properties and network interactions in determining the pattern of impulse production by the motorneurons; however, the synaptic mechanisms by which the pacemakers influence the motorneurons, which has previously been thought to be mainly chemical in lobsters, appears to contain a significant electrical component.

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“…All intracellular recordings were made from LC3, 4, and 5 somata. LC structure consists of a cell soma and proximal neurite that projects to a common spike initiation area located posterior to the anterior branch point (Hartline, 1967;Tazaki and Cooke, 1983;Cooke, 2002;Ransdell et al, 2013) (Fig. 1A).…”

Section: Methodsmentioning

confidence: 99%

“…1A, 2 A, B). Isolated somata carry ionic conductances that generate driver potential output (Tazaki, 1972;Cooke, 1983, 1986;Cooke, 2002), even with ligatures as close as 200 m from the soma (Tazaki and Cooke, 1983).…”

Section: Methodsmentioning

confidence: 99%

Neurons within the Same Network Independently Achieve Conserved Output by Differentially Balancing Variable Conductance Magnitudes

Ransdell¹,

Nair

Schulz³

2013

Journal of Neuroscience

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Biological and theoretical evidence suggest that individual neurons may achieve similar outputs by differentially balancing variable underlying ionic conductances. Despite the substantial amount of data consistent with this idea, a direct biological demonstration that cells with conserved output, particularly within the same network, achieve these outputs via different solutions has been difficult to achieve. Here we demonstrate definitively that neurons from native neural networks with highly similar output achieve this conserved output by differentially tuning underlying conductance magnitudes. Multiple motor neurons of the crab (Cancer borealis) cardiac ganglion have highly conserved output within a preparation, despite showing a 2-4-fold range of conductance magnitudes. By blocking subsets of these currents, we demonstrate that the remaining conductances become unbalanced, causing disparate output as a result. Therefore, as strategies to understand neuronal excitability become increasingly sophisticated, it is important that such variability in excitability of neurons, even among those within the same individual, is taken into account.

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Separation of neuronal sites of driver potential and impulse generation by ligaturing in the cardiac ganglion of the lobster,Homarus americanus

Cited by 35 publications

References 30 publications

Rapid Homeostatic Plasticity of Intrinsic Excitability in a Central Pattern Generator Network Stabilizes Functional Neural Network Output

Rapid Homeostatic Plasticity of Intrinsic Excitability in a Central Pattern Generator Network Stabilizes Functional Neural Network Output

Endogenous burst-organizing potentials in two classes of neurons in the lobster cardiac ganglion respond differently to alterations in divalent ion concentration

Neurons within the Same Network Independently Achieve Conserved Output by Differentially Balancing Variable Conductance Magnitudes

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