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DONALD M, MAYNARD 



50/ sec. 



mm 



100 /sec 



Fig. 8. Inhibitory summation {Paiiulirns). Inhibitor stimulated before driving 

 stimulus with trains of stimuli at 50/sec and 100/sec. Figures give the number 

 of impulses in each train, N, normal response to stimulation of ganglion with 

 no inhibition. Stimulating electrodes on inhibitor nerve and posterior ganglion; 

 recording electrodes on anterior ganglion. Time signal, 60/sec (Maynard, 1954). 



this, continued inhibition produces little increase in rebound, suggesting a 

 similarity between the time course of development of such post-inhibitory 

 excitation and the time course of adaptation during prolonged inhibition. 



Rebound excitation may be quite effective. In many cases it causes greater 

 maximum activity than that produced by high-frequency stimulation of the 

 accelerator nerves. In other preparations, it apparently leads to the pheno- 

 menon of paradoxical driving. 



Paradoxical driving. As certain preparations age they lose spontaneous 

 activity and fire erratically in small bursts with very long interburst periods. 

 A short train of inhibitory stimuH given in the interburst of such a prepara- 

 tion often may be followed, after a latent pause of about 1 sec, by a burst 

 of ganglionic activity. If the inhibitory train is repeated after a proper interval, 

 a burst again follows so that the previously inactive ganglion can be driven 

 by brief, properly spaced trains of inhibition at a rate somewhat below 

 normal frequencies. Ganglion activity never occurred during inhibitory 

 trains (Fig. 11). 



