C-PR Neuron of<i>Aplysia</i>Has Differential Effects on “Feeding” Cerebral Interneurons, Including Myomodulin-Positive CBI-12

Hurwitz, Itay; Perrins, R; Xin, Yuanpei; Weiss, Klaudiusz R.; Kupfermann, Irving

doi:10.1152/jn.1999.81.2.521

Cited by 48 publications

(49 citation statements)

References 32 publications

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“…Like the MMG2-DPs, the MCCs also modulate the neurons B4/5 (Weiss and Kupfermann, 1976). The feeding system may be simultaneously modulated by both extrinsic systems, because both the MCC and the P-BPNS are activated by C-PR, a neuron important for the appetitive phase of feeding behavior (Teyke et al, 1990;Hurwitz et al, 1999;Robie et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Identification of a New Neuropeptide Precursor Reveals a Novel Source of Extrinsic Modulation in the Feeding System ofAplysia

et al. 2005

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The Aplysia feeding system is advantageous for investigating the role of neuropeptides in behavioral plasticity. One family of Aplysia neuropeptides is the myomodulins (MMs), originally purified from one of the feeding muscles, the accessory radula closer (ARC). However, two MMs, MMc and MMe, are not encoded on the only known MM gene. Here, we identify MM gene 2 (MMG2), which encodes MMc and MMe and four new neuropeptides. We use matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to verify that these novel MMG2-derived peptides (MMG2-DPs), as well as MMc and MMe, are synthesized from the precursor. Using antibodies against the MMG2-DPs, we demonstrate that neuronal processes that stain for MMG2-DPs are found in the buccal ganglion, which contains the feeding network, and in the buccal musculature including the ARC muscle. Surprisingly, however, no immunostaining is observed in buccal neurons including the ARC motoneurons. In situ hybridization reveals only few MMG2-expressing neurons that are mostly located in the pedal ganglion. Using immunohistochemical and electrophysiological techniques, we demonstrate that some of these pedal neurons project to the buccal ganglion and are the likely source of the MMG2-DP innervation of the feeding network and musculature. We show that the MMG2-DPs are bioactive both centrally and peripherally: they bias egestive feeding programs toward ingestive ones, and they modulate ARC muscle contractions. The multiple actions of the MMG2-DPs suggest that these peptides play a broad role in behavioral plasticity and that the pedal-buccal projection neurons that express them are a novel source of extrinsic modulation of the feeding system of Aplysia.

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Section: Discussionmentioning

confidence: 99%

Identification of a New Neuropeptide Precursor Reveals a Novel Source of Extrinsic Modulation in the Feeding System ofAplysia

et al. 2005

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“…Previous studies established that consummatory motor programs can be generated by stimulating individual interneurons within the buccal CPG (Hurwitz et al 1997;Kabotyanski et al 1998;Susswein and Byrne 1988;Teyke et al 1993), by stimulating specific cerebralbuccal interneurons (CBIs; Hurwitz et al 1999Hurwitz et al , 2003Rosen et al 1991;Sánchez and Kirk 2000) and by stimulating certain nerves of the buccal and cerebral ganglia (Chiel et al 1986;Lechner et al 2000;Nargeot et al 1997;Plummer and Kirk 1990). Moreover, application of neuromodulators can activate motor programs (Kabotyanski et al 2000;Susswein et al 1996;Teyke et al 1993).…”

Section: Electrophysiologymentioning

confidence: 99%

Endogenous Motor Neuron Properties Contribute to a Program-Specific Phase of Activity in the Multifunctional Feeding Central Pattern Generator ofAplysia

Serrano

Martinez-Rubio²

2007

Journal of Neurophysiology

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Multifunctional central pattern generators (CPGs) are circuits of neurons that can generate manifold actions from a single effector system. This study examined a bilateral pair of pharyngeal motor neurons, designated B67, that participate in the multifunctional feeding network of Aplysia californica. Fictive buccal motor programs (BMPs) were elicited with four distinct stimulus paradigms to assess the activity of B67 during ingestive versus egestive patterns. In both classes of programs, B67 fired during the phase of radula protraction and received a potent inhibitory postsynaptic potential (IPSP) during fictive radula retraction. When programs were ingestive, the retraction phase IPSP exhibited a depolarizing sag and was followed by a postinhibitory rebound (PIR) that could generate a postretraction phase of impulse activity. When programs were egestive, the depolarizing sag potential and PIR were both diminished or were not present. Examination of the membrane properties of B67 disclosed a cesium-sensitive depolarizing sag, a corresponding Ih-like current, and PIR in its responses to hyperpolarizing pulses. Direct IPSPs originating from the influential CPG retraction phase interneuron B64 were also found to activate the sag potential and PIR of B67. Dopamine, a modulator that can promote ingestive behavior in this system, enhanced the sag potential, Ih-like current, and PIR of B67. Finally, a pharyngeal muscle contraction followed the radula retraction phase of ingestive, but not egestive motor patterns. It is proposed that regulation of the intrinsic properties of this motor neuron can contribute to generating a program-specific phase of motor activity.

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“…For example, CBI-2 is only one of the elements of a network of command-like interneurons that includes CBI-1, CBI-3, and CBI-12 (Rosen et al 1991;Hurwitz et al 1999;Jing and Weiss 2001). These neurons process sensory information and control feeding through synaptic connections with CPG elements, including B31/32 (Hurwitz et al 1997(Hurwitz et al , 1999Sánchez and Kirk 2000, 2001Morgan et al 2001). One intriguing locus for pairing-specific plasticity is also neuron B51 (Plummer and Kirk 1990), which has been implicated in operant conditioning of feeding behavior both in vivo (Brembs et al 2002) and in vitro (Nargeot et al 1999a,b).…”

Section: Sites Of Associative Plasticity In the In Vitro Analog Of CLmentioning

confidence: 99%

“…CBI-2 was identified according to the location of its soma in the M cluster as well as its spontaneous IPSPs (Rosen et al 1991). Also, the identification of CBI-2 was confirmed at the end of the experiment by checking the ability of the neuron to drive multiple BMPs, when a 100-sec depolarizing pulse (6-12 nA) was injected into the cell (Rosen et al 1991;Hurwitz et al 1999;Jing and Weiss 2001). Neurons that did not fulfill this criterion were discarded.…”

Section: Experiments 2: Neuron B31/32mentioning

confidence: 99%

In Vitro Analog of Classical Conditioning of Feeding Behavior in Aplysia

Mozzachiodi¹,

Lechner²,

Baxter³

et al. 2003

Learn. Mem.

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The feeding behavior of Aplysia californica can be classically conditioned using tactile stimulation of the lips as a conditioned stimulus (CS) and food as an unconditioned stimulus (US). Moreover, several neural correlates of classical conditioning have been identified. The present study extended previous work by developing an in vitro analog of classical conditioning and by investigating pairing-specific changes in neuronal and synaptic properties. The preparation consisted of the isolated cerebral and buccal ganglia. Electrical stimulation of a lip nerve (AT 4 ) and a branch of the esophageal nerve (En 2 ) served as the CS and US, respectively. Three protocols were used: paired, unpaired, and US alone. Only the paired protocol produced a significant increase in CS-evoked fictive feeding. At the cellular level, classical conditioning enhanced the magnitude of the CS-evoked synaptic input to pattern-initiating neuron B31/32. In addition, paired training enhanced both the magnitude of the CS-evoked synaptic input and the CS-evoked spike activity in command-like neuron CBI-2. The in vitro analog of classical conditioning reproduced all of the cellular changes that previously were identified following behavioral conditioning and has led to the identification of several new learning-related neural changes. In addition, the pairing-specific enhancement of the CS response in CBI-2 indicates that some aspects of associative plasticity may occur at the level of the cerebral sensory neurons.

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C-PR Neuron ofAplysiaHas Differential Effects on “Feeding” Cerebral Interneurons, Including Myomodulin-Positive CBI-12

Cited by 48 publications

References 32 publications

Identification of a New Neuropeptide Precursor Reveals a Novel Source of Extrinsic Modulation in the Feeding System ofAplysia

Identification of a New Neuropeptide Precursor Reveals a Novel Source of Extrinsic Modulation in the Feeding System ofAplysia

Endogenous Motor Neuron Properties Contribute to a Program-Specific Phase of Activity in the Multifunctional Feeding Central Pattern Generator ofAplysia

In Vitro Analog of Classical Conditioning of Feeding Behavior in Aplysia

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