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Conditional rhythmicity and synchronization by dopamine in a bilateral pair of motor neurons
Author(s) -
Serrano Geidy Enid,
Miller Mark W
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a412-a
Subject(s) - bursting , neuroscience , aplysia , excitatory postsynaptic potential , dopaminergic , dopamine , central pattern generator , electrophysiology , inhibitory postsynaptic potential , interneuron , biology , optogenetics , rhythm , psychology , medicine
Central pattern generator (CPG) networks typically produce rhythmic motor programs in which neurons with common functions fire in phase. The mechanisms involved in the generation of this property are still a matter of debate. This investigation was directed toward understanding rhythmicity and synchrony in bilaterally paired motor neurons, B67R and B67L, in the feeding motor system of Aplysia californica . Previous studies showed that this bursting neuron innervates multiple buccal muscles (I 11 , I 12 , salivary duct; Nagahama and Takata, 1987; Park et al, 1999). We have observed that, in the absence of motor programs, B67 exhibits spontaneous non‐rhythmic bursting. Spontaneous bursts are highly stereotyped and appear to reflect the properties of an underlying TTX‐resistant driver potential. Under control conditions, the spontaneous bursting of the paired B67 neurons (one in each hemiganglion) was not synchronous. However, the neuromodulator dopamine conferred rhythmicity and synchrony to the paired B67s. Dopamine modified several electrophysiological features of B67, including the duration of its driver potential, the magnitude of a sag potential in responses to hyperpolarizing current pulses, and post‐inhibitory rebound. Finally, B67 was found to receive direct excitatory synaptic input from B65, an influential dopaminergic interneuron (Kabotyanski et al 1998). It is proposed that one action of dopaminergic signaling in this system is to promote rhythmicity and synchrony of bilateral salivary motor activity. Supported by the National Institutes of Health: DRS RCMI RR‐03051, NIGMS MBRS: GM‐08224 & GM‐61838‐03, and a Society for Neuroscience MNFP fellowship (NIMH & NINDS).