Functional Organization of the Cardiac Ganglion of the Lobster, Homarus americanus

Abstract

External recording and stimulation techniques were used to determine which neurons and interactions are essential for production of the periodic burst discharge in the lobster cardiac ganglion. Burst activity can be modulated by brief single shocks applied to the four small cells, but not by similar stimulation of the five large cells, suggesting that normally one or more small cells primarily determine burst rate and duration. Repetitive electrical stimulation of large cells initiates spike activity in small cells, probably via excitatory synaptic and/or electrotonic connections which may normally act to prolong bursts and decrease burst rate. Transection of the ganglion can result in burst activity in small cells in the partial or complete absence of large cell spike activity, but large cells isolated from small cell excitatory synaptic input by transection or by application of dinitrophenol do not burst. Generally, transections which decrease excitatory feedback to small cells are accompanied by an increase in burst rate, but mean spike frequency over an entire burst cycle stabilizes at the original level within 10-30 min for various groups of cells whose spike-initiating sites are still intact. These and previous results suggest that the system is two layered: one or more small cells generate the burst pattern and impose it on the large cells which are the system's motorneurons.

Multiple modulators act on the cardiac ganglion of the crab,Cancer borealis

“…The heart muscle fibers are innervated by five motor neurons (Alexandrowicz, 1932) that make reciprocal chemical and electrical excitatory synapses with four pacemaker neurons that initiate the bursting activity of the whole network (Hartline, 1967;Hartline, 1979;Mayeri, 1973;Tazaki and Cooke, 1979a;Tazaki and Cooke, 1979b;Tazaki and Cooke, 1979c). The CG also receives excitatory and inhibitory inputs from the central nervous system and the CG is a direct target for neuromodulators released from the POs (Alexandrowicz, 1932;Cooke, 2002).…”

Regulation of the Crab Heartbeat by FMRFamide-Like Peptides: Multiple Interacting Effects on Center and Periphery

“…The decrease in burst frequency can then be explained as a secondary consequence of the increased burst strength, through the reciprocal negative interaction between burst strength and frequency (Fig. 11, arrow 6) that has been well described in the cardiac ganglia of lobsters and crabs (Benson 1980;Mayeri 1973;Tazaki and Cooke 1990).…”

Artificial pacemaking of breathing movements by medullary stimulation in adult lampreys.

“…The current information may be summarised as follows: Crustacean heart ganglion is organized essentially by the small cells and large cells, and the interaction between them mainly occurs through electrical connection (WATANABE et al, 1967a;TAZAKI and COOKE, 1979a). Under normal conditions the pacemaker is located in certain small cells which send a burst of impulses into the large cells (HAGIWARA, 1961;MAYERI, 1973 ;TAMEYASU, 1976). The large cells, acting as followers, provide efferent motor output to the cardiac muscle fibers, and cause heart contraction (ANDERSON and COOKE, 1971;KURAMOTO and KUWASAWA, 1980).…”

“…In the case of crustacean heart, a single stimulus applied to the heart ganglion also induces an extra-burst of discharges similar in shape and duration to a spontaneously occurring one which caused a tetanic contraction of the cardiac muscle (WATANABE et al, 1967b ;MAYERI, 1973 ;MATSUI et al, 1977 ;TAZAKI and COOKE, 1979a). However, in the case of breathing (in mammals, probably as well as in other gnathostomata), respiratory pacemaking by pontine or medullary stimulation is not easily achieved, probably because of complications in the neuron network for respiratory rhythm generation, although inspiratory or expiratory arrest and/or transient respiratory phase-switching can be produced according to the stimulation site in the medulla or in the pons (PITTS et al, 1939 ;BAXTER and OLSZEWSKI, 1955 ;NGAI and WANG, 1957 ;BURNS and SALMOIRAGHI, 1960;COHEN et al, 1976).…”