A switch between two modes of synaptic transmission mediated by presynaptic inhibition

Coleman, Melissa J.; Meyrand, Pierre; Nusbaum, Michael P.

doi:10.1038/378502a0

Cited by 147 publications

(356 citation statements)

References 27 publications

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“…Experiments in which either MCN1 or CPN2 was removed selectively suggest that the relative contributions of these two projection neurons to the VCN-elicited gastric mill rhythm reflect their previously characterized actions on gastric mill neurons. The contribution of MCN1 includes a modulatory excitation of some neurons (e.g., LG, DG) and ionotropic excitation of others (e.g., Int1) Coleman et al, 1995;Wood et al, 2000). These actions contribute to the ability of MCN1 stimulation to drive the gastric mill rhythm (Coleman et al, 1995;Bartos et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

“…The contribution of MCN1 includes a modulatory excitation of some neurons (e.g., LG, DG) and ionotropic excitation of others (e.g., Int1) Coleman et al, 1995;Wood et al, 2000). These actions contribute to the ability of MCN1 stimulation to drive the gastric mill rhythm (Coleman et al, 1995;Bartos et al, 1999). The CPN2 contribution includes fast excitation of the LG and GM neurons and inhibition of the DG, AM, IC, and MG neurons.…”

Section: Discussionmentioning

confidence: 99%

“…Intrasomatic recordings were performed with sharp glass microelectrodes (15-30 M⍀) filled with 4 M potassium acetate and 20 mM KCl. Intra-axonal recordings of neurons also were performed in some experiments by using sharp glass microelectrodes (20 -30 M⍀) filled with 1 M KCl (Coleman et al, 1995). All intracellular signals were recorded with Axoclamp 2B amplifiers (Axon Instruments, Foster City, CA).…”

Section: Methodsmentioning

confidence: 99%

“…MCN1 has excitatory actions on all gastric mill circuit neurons, including the gastropyloric IC and ventricular dilator (VD) neurons Coleman et al, 1995;Bartos and Nusbaum, 1997;Blitz et al, 1999;Beenhakker, 2004) (Fig. 1 B).…”

Section: Selective Removal Of Cpn2 Alters the Vcn-elicited Gastric MImentioning

confidence: 99%

“…B, Schematic of the identified MCN1 and CPN2 synaptic actions on the gastric mill neurons. MCN1 data were obtained from Coleman and Nusbaum (1994), Coleman et al (1995), andBeenhakker (2004). CPN2 data were obtained from Norris et al (1994).…”

Section: Selective Removal Of Cpn2 Alters the Vcn-elicited Gastric MImentioning

confidence: 99%

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Mechanosensory Activation of a Motor Circuit by Coactivation of Two Projection Neurons

Beenhakker¹,

Nusbaum²

2004

J. Neurosci.

102

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Individual neuronal circuits can generate multiple activity patterns because of the influence of different projection neurons. However, in most systems it has been difficult to identify and assess the relative contribution of all upstream neurons responsible for the activation of any single activity pattern by a behaviorally relevant stimulus. To elucidate this issue, we used the stomatogastric nervous system (STNS) of the crab. The STNS includes the gastric mill (chewing) motor circuit in the stomatogastric ganglion (STG) and no more than 20 projection neurons that innervate the STG. We previously identified at least some (four) of the projection neurons that are activated directly by the ventral cardiac neuron (VCN) system, a population of mechanosensory neurons that activates the gastric mill circuit. Here we show that two of these projection neurons, the previously identified modulatory commissural neuron 1 (MCN1) and commissural projection neuron 2 (CPN2), are necessary and likely sufficient for the initiation/maintenance of the VCN-elicited gastric mill rhythm. Selective inactivation of either MCN1 or CPN2 still enabled a VCN-elicited gastric mill rhythm. However, because MCN1 and CPN2 have different actions on gastric mill neurons, these manipulations resulted in rhythms distinct from each other and from that occurring in the intact system. After removal of both MCN1 and CPN2, VCN stimulation failed to activate the gastric mill rhythm. Selective conjoint stimulation of MCN1 and CPN2, approximating their VCN-elicited activity patterns and firing frequencies, elicited a VCN-like gastric mill rhythm. Thus the VCN mechanosensory system elicits the gastric mill rhythm via its activation of a subset of the relevant projection neurons.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Selective Removal Of Cpn2 Alters the Vcn-elicited Gastric MImentioning

confidence: 99%

Section: Selective Removal Of Cpn2 Alters the Vcn-elicited Gastric MImentioning

confidence: 99%

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Mechanosensory Activation of a Motor Circuit by Coactivation of Two Projection Neurons

Beenhakker¹,

Nusbaum²

2004

J. Neurosci.

102

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Ultrastructure of the stomatogastric ganglion neuropil of the crab, Cancer borealis

Kilman

Marder

1996

J. Comp. Neurol.

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The stomatogastric ganglion (STG) of the crab, Cancer borealis, contains the neural networks responsible for rhythmic pattern generation of the foregut. Neuron counts indicate that the STG of C. borealis has 25-26 neurons, 4-5 fewer than that found in lobsters. We describe the ultrastructural features of the ganglion by focusing on those that may be involved in storage, release, or range of action of peptide modulators, including a lacunar system and multiple types of intercellular junctions. In the neuropil, we identify five synaptic profile classes that contain the invertebrate presynaptic apparatus (dense bars, small clear vesicles), two of which also contain dense core (modulator-containing) vesicles. These latter two are comprised of multiple immunocytochemical classes that are not easily distinguished by structural criteria. In addition, we find neurohemal-like profiles that contain primarily dense core vesicles. Our finding that multiple profile types in the STG possess modulator-containing vesicles coincides with immunocytochemical results better than do previous ultrastructural studies that report only one such profile type. We show that a single modulatory input, stomatogastric nerve axon 1, makes only classical synapses and not neurohemal-like profiles, although some modulators are found in both these profile types. These data provide the groundwork for understanding the architecture of modulatory input-target interactions and suggest ways that the specificity of modulatory effects within a complex neuropil may be attained.

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Sequential developmental acquisition of neuromodulatory inputs to a central pattern-generating network

et al. 1999

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The activity of the adult stomatogastric ganglion (STG) depends on a large number of aminergic and peptidergic modulatory inputs. Our aim is to understand the role of these modulatory inputs in the development of the central pattern‐generating networks of the STG. Therefore, we analyze the developmental and adult expressions of three neuropeptides in the stomatogastric nervous system of the lobsters Homarus americanus and Homarus gammarus by using wholemount immunocytochemistry and confocal microscopy. In adults, red pigment‐concentrating hormone (RPCH)‐like, proctolin‐like, and a tachykinin‐like immunoreactivity are present in axonal projections to the STG. At 50% of embryonic development (E50), all three peptides stain the commissural ganglia and brain, but only RPCH‐ and proctolin‐like immunoreactivities stain axonal arbors in the STG. Tachykinin‐like immunoreactivity is not apparent in the STG until larval stage II (LII). The RPCH‐immunoreactive projection to the STG consists of two pairs of fibers. One pair stains for RPCH immunoreactivity at E50; the second RPCH‐immunoreactive pair does not stain until about LII. One pair of the RPCH fibers double labels for tachykinin‐like immunoreactivity. The adult complement of neuromodulatory inputs is not fully expressed until close to the developmental time at which major changes in the STG motor patterns occur, suggesting that neuromodulators play a role in the tuning of the central pattern generators during development. J. Comp. Neurol. 408:335–351, 1999. © 1999 Wiley‐Liss, Inc.

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A switch between two modes of synaptic transmission mediated by presynaptic inhibition

Cited by 147 publications

References 27 publications

Mechanosensory Activation of a Motor Circuit by Coactivation of Two Projection Neurons

Mechanosensory Activation of a Motor Circuit by Coactivation of Two Projection Neurons

Ultrastructure of the stomatogastric ganglion neuropil of the crab, Cancer borealis

Sequential developmental acquisition of neuromodulatory inputs to a central pattern-generating network

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