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The extent to which individual neural networks can produce phase-constant motor patterns as cycle frequency is altered has not been studied extensively. I investigated this issue in the well-defined, rhythmic pyloric neural network. When pyloric cycle frequency is altered three- to fivefold, pyloric inter-neuronal delays shift by hundreds to thousands of(More)
The pyloric pattern approximately maintains phase over a three- to fivefold frequency range when the pattern is defined by the pacemaker burst beginning. However, in this reference frame certain pattern elements maintain phase better than others, which suggests phase-maintaining subgroups might exist. Reanalysis of these data in reference frames defined by(More)
Legged locomotion results from a combination of central pattern generating network (CPG) activity and intralimb and interlimb sensory feedback. Data on the neural basis of interlimb coordination are very limited. We investigated here the influence of stepping in one leg on the activities of neighboring-leg thorax-coxa (TC) joint CPGs in the stick insect(More)
We aimed to determine the neuronal parameters controlling the contraction of slowly contracting, non-twitch ("tonic") muscles driven by rhythmic neuronal activity. These muscles are almost completely absent in mammals but are common in lower vertebrates and invertebrates. Slow muscles are often believed to function primarily in tonic motor patterns.(More)
Distributed neural networks (ones characterized by high levels of interconnectivity among network neurons) are not well understood. Increased insight into these systems can be obtained by perturbing network activity so as to study the functions of specific neurons not only in the network's "baseline" activity but across a range of network activities. We(More)
Acting through a cAMP-cAMP-dependent protein kinase (cAPK) cascade, members of two neuropeptide families, the small cardioactive peptides and myomodulins, modulate contraction amplitude and relaxation rate in the accessory radula closer (ARC) muscle of the marine mollusc Aplysia californica. An approximately 750-kDa phosphoprotein was identified in the ARC(More)
We describe three slow muscles that responded to low-frequency modulation of a high-frequency neuronal input and, consequently, could express the motor patterns of neural networks whose neurons did not directly innervate the muscles. Two of these muscles responded to different frequency components present in the same input, and as a result each muscle(More)
The pyloric network of decapod crustaceans has been intensively studied electrophysiologically in the infraorders Astacidea, Brachyura, and Palinura. The morphology of some or all pyloric neurons has been well described in Astacidea and Brachyura, but less so in Palinura. Given the large evolutionary distance between these three groups, and the large amount(More)
As our ability to communicate by Morse code illustrates, nervous systems can produce motor outputs, and identify sensory inputs, based on temporal patterning alone. Although this ability is central to a wide range of sensory and motor tasks, the ways in which nervous systems represent temporal patterns are not well understood. I show here that individual(More)
The neuropeptides, proctolin and FMRFamide, increase the frequency of, and modify the motor pattern produced by, the stomatogastric ganglion (STG) of the crab, Cancer irroratus. Both proctolin-like and FMRFamide-like immunoreactivities are present in fibers in the stomatogastric nerve which terminate in the neuropile of the STG. The neural output of the STG(More)