Further identification of neurons in the abdominal ganglion ofAplysia using behavioral criteria

Koester, John; Kandel, Eric R.

doi:10.1016/0006-8993(77)90435-8

Cited by 116 publications

(56 citation statements)

References 49 publications

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“…Following removal of the sheath, the cells were isolated from the ganglia with glass microelectrodes in one of two ways: either the cell body alone was isolated, or the cell was removed with an initial segment of axon (Schacher and Proshansky, 1983). LlO, left upper quadrant cells L2 to L6 (LUQ cells), and right upper quadrant cells R3 to R13 (RUQ cells) were identified on the basis of size, position, and pigmentation (Koester and Kandel, 1977). Each LUQ and RUQ cell was treated as a member of a homogeneous population, since LlO in viva connects with all cells in the LUQ cluster (dual component IPSP) and does not connect with any RUQ cell (Kandel et al, 1967;Koester and Kandel, 1977).…”

Section: Methodsmentioning

confidence: 99%

Identified Aplysia neurons form specific chemical synapses in culture

Camardo¹,

Proshansky²,

Schacher³

1983

J. Neurosci.

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Identified neurons from the abdominal ganglion of the marine mollusc Aplysiu californica make specific transmitter-mediated synapses in dissociated cell culture. The cholinergic interneuron LlO makes synapses in vitro with one group of its follower cells, the left upper quadrant cells, and these connections exhibit the features of these synapses in uivo when the postsynaptic cells are plated with their initial axon segments. Furthermore, LlO will avoid making synapses with right upper quadrant cells, which contain cholinergic receptors but do not synapse with LlO in Go.This in vitro system can therefore be used as a model in which to study the development of specific neuronal connections.

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Section: Methodsmentioning

confidence: 99%

Identified Aplysia neurons form specific chemical synapses in culture

Camardo¹,

Proshansky²,

Schacher³

1983

J. Neurosci.

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“…One kind of observation that argues against a completely distributed organization is the existence of interneurons with specific function. Electrophysiological measurements have suggested the existence of 22 interneuron types (composed of a total of 65 neurons) that are involved in withdrawal reflexes (Koester and Kandel, 1977;Byrne and Koester, 1978;Byrne, 1980Byrne, , 1983Hawkins et al, 198 1;Frost, 1987;Alevizos et al, 1989a,b;Koester, 1989;Trudeau and Castellucci, 1992b;Koester et al, 1993;J. Koester, unpublished observations).…”

Section: Cross-correlationsmentioning

confidence: 99%

Distributed aspects of the response to siphon touch in Aplysia: spread of stimulus information and cross-correlation analysis

Tsau

et al. 1994

J. Neurosci.

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We examined two aspects of the response to siphon stimulation in an attempt to test the hypothesis that the Aplysia CNS functions as a distributed system. First, we estimated the number of central neurons that respond to a light touch to the siphon skin. We made voltage- sensitive dye recordings from the abdominal, pleural, pedal, and cerebral ganglia. From these recordings we estimated that 220 abdominal neurons, 110 pleural neurons, and 650 pedal neurons were affected by the light touch. Thus, the information about this mild and localized stimulus is very widely distributed within the Aplysia CNS. This result allows the possibility that the Aplysia CNS functions as a distributed system. If only a small number of neurons had responded to the touch, it would have supported the conclusion that the gill-withdrawal reflex could be generated by a small, dedicated circuit. Second, we searched for correlations between the spike times of the individual abdominal ganglion neurons. Two time scales were examined: a millisecond time scale corresponding to the duration of a fast synaptic potential and a seconds time scale corresponding to the duration of the gill-withdrawal movement. Neuron pairs with highly correlated spike activity on a millisecond time scale must be connected by (or have a common input that uses) relatively powerful, fast, excitatory synapses. We expected that this kind of synaptic interaction would be relatively rare in nervous systems that functioned in a distributed manner. Indeed, only 0.3% of the neuron pairs had correlation coefficients of 0.15 or greater. These correlations accounted for approximately 2% of the action potentials generated in response to siphon stimulation. Thus, large, fast excitatory synaptic interactions appear to be relatively unimportant. This result is consistent with the hypothesis that the abdominal ganglion functions as a distributed system. When the longer time scale was used for the cross-correlograms, a large fraction of the cell pairs had correlated activity because many neurons are activated by the stimulus. It was not possible to interpret the slow correlations in terms of actual synaptic interactions between individual neurons. Our results are consistent with the possibility that the abdominal ganglion functions in a distributed manner. However, this evaluation is indirect and thus only tentative conclusions can be drawn. Evidence from several sources suggests that the neuronal interactions for generating the Aplysia gill-withdrawal reflex are complex.

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“…In addition, inhibitory postsynaptic potentials (IPSPs) can cause long-lasting (0.5-1 sec) and large (10-15 mV) hyperpolarization of cell L1O. Cell L10 produces different synaptic actions through its various branches (13)(14)(15) The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §17734 solely to indicate this fact.…”

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confidence: 99%

Presynaptic membrane potential affects transmitter release in an identified neuron in Aplysia by modulating the Ca ²⁺ and K ⁺ currents

Shapiro

Castellucci

Kandel

1980

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

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We have examined the relationships between the modulation of transmitter release and of specific ionic currents by membrane potential in the cholinergic interneuron LIO of the abdominal ganglion of Aplysia californica. The presynaptic cell body was voltage-clamped under various pharmacological conditions and transmitter release from the terminals was assayed simultaneously by recording the synaptic potentials in the stsynaptic cell. When cell L1O was voltageclamped from a holding potential of -60 mV in the presence of tetrodotoxin, graded transmitter release was evoked by de- In some spike-generating neurons the presynaptic terminals controlling transmitter release are electrically sufficiently close to the cell body so that the release of transmitter from the terminals can be modified by injecting current into the cell body (1-4). Klein and Kandel (5) have recently found that changes in the Ca2+ current in the cell body of an Aplysia neuron parallel changes in transmitter release at the terminals. These two sets of observations suggested to us that we might be able to examine the relationships between transmitter release and specific ionic currents of the presynaptic membrane. Toward this end we have combined two separate techniques: (i) pharmacological separation and voltage-clamp analysis of the ionic currents in the cell body of the presynaptic neuron and (ii) assay of transmitter release obtained by means of intracellular recordings of the synaptic potential in the post-synaptic cells. We have found that this combined technique provides a powerful method for studying changes in specific ionic conductances associated with various presynaptic mechanisms for synaptic plasticity.For these studies we have used the identified cholinergic neuron L10 of the abdominal ganglion of Aplysia. We eliminated impulse conduction by blocking Na+ channels with tetrodotoxin (TTX) and found that graded depolarizing commands, applied to the membrane of the presynaptic cell body under voltage-clamp control, caused graded transmitter release from the terminals as determined by the graded changes in the synaptic potential in the postsynaptic cell. Although in many cases we probably lacked ideal voltage control of the terminals, this procedure nonetheless allowed sufficient control to study transmitter release while examining specific ionic currents in the soma of the presynaptic neuron. Voltage control can be further improved by axotomizing the presynaptic cell (6, 7) and by adding pharmacological agents that block each of the three known outward K+ currents (8) and thereby also lengthen the effective space constant of the neuron.By using these approaches, we have found that depolarizing the presynaptic membrane potential enhances transmitter release by two mechanisms: (i) by activation of a steady-state Ca2+ current and (ii) by decreasing the outward K+ currents activated by a step depolarization (9, 10). This decrease in the K+ currents increases the duration of the spike and, therefore, the transient Ca2+ current activat...

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Further identification of neurons in the abdominal ganglion ofAplysia using behavioral criteria

Cited by 116 publications

References 49 publications

Identified Aplysia neurons form specific chemical synapses in culture

Identified Aplysia neurons form specific chemical synapses in culture

Distributed aspects of the response to siphon touch in Aplysia: spread of stimulus information and cross-correlation analysis

Presynaptic membrane potential affects transmitter release in an identified neuron in Aplysia by modulating the Ca ²⁺ and K ⁺ currents

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Further identification of neurons in the abdominal ganglion ofAplysia using behavioral criteria

Cited by 116 publications

References 49 publications

Identified Aplysia neurons form specific chemical synapses in culture

Identified Aplysia neurons form specific chemical synapses in culture

Distributed aspects of the response to siphon touch in Aplysia: spread of stimulus information and cross-correlation analysis

Presynaptic membrane potential affects transmitter release in an identified neuron in Aplysia by modulating the Ca 2+ and K + currents

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Presynaptic membrane potential affects transmitter release in an identified neuron in Aplysia by modulating the Ca ²⁺ and K ⁺ currents