. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 270 NORMAN B. RUSH FORT 11 bursts) and short intervals (within hursts) in Aplysia are thought to result from a single generating mechanism. In Hydra, the interval lengths of long intervals were found to have quite a different functional relationship to their position in an inter-hurst interval from that of short intervals within hursts. Both in unstimulated preparations of H. pirardi, and in H. pseudoligactis induced to give bursts of potentials by in- creased electrode suction the intervals decrease successively in length t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 270 NORMAN B. RUSH FORT 11 bursts) and short intervals (within hursts) in Aplysia are thought to result from a single generating mechanism. In Hydra, the interval lengths of long intervals were found to have quite a different functional relationship to their position in an inter-hurst interval from that of short intervals within hursts. Both in unstimulated preparations of H. pirardi, and in H. pseudoligactis induced to give bursts of potentials by in- creased electrode suction the intervals decrease successively in length throughout the inter-burst interval. The interval immediately following a burst was signif- icantly longer than the subsequent intervals prior to the next burst. The different patterns suggest that different mechanisms seem to be involved in the production of short and long MULTIPLE EVENT GENERATOR SINGLE EVENT GENERATOR w CO o o OL O FIGURE 9. Schematic model of the CP system of Hydra. An arrow indicates excitatory input, a reverse arrow indicates inhibitory input. The following model is offered as one which could account for the observed CP patterns. The proposed model is shown schematically in Figure 9. There are two elements, one producing single events and another producing multiple events. Both elements trigger the CP conducting system and thus initiate CP's. The multiple event generator has short term excitation to itself, such excitation leads to firing in bursts, and is also responsible for the decrease of interval lengths in the initial phases of the burst. There is also inhibitory feedback to the multiple event generator, probably mediated via the CP conducting system. This inhibitory feedback is slow rising, and the inhibitory effects of several CP's in succession are accumulative. The growing inhibition within a burst leads to increased intervals toward the end of the burst and eventually the termination of the burst. The joint effect of the excitatory a
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
