CARDIAC INHIBITION IN DECAPOD CRUSTACEA 



175 



w!js ! — ife,.<by<l,^""*-'a»ggTO: •-■»< ' ^■'' ■ ' V--^ ' >* 



■ V»lll»i flUiw»iimiii»<'l»ii.i 



B 



^iSirjs^^W^^V- 



m,fm 



JU-. 



iHli^W^ 



■lyjau „ n u L I 



i^V^**^'^^f*'*^M^»^^ 



Fig. 28. Effect of GABA on burst pattern, applied to pacemakers only 

 (Homarus). a. Normal burst, b. Burst after concentrated GABA solution applied 

 to posterior pacemakers, c. Burst after washing. Upper trace, a, from anterior 

 portion of ganglion (follower neurons); lower trace, p, from posterior portion of 

 ganglion (pacemaker neurons). (•) marks same spike complex in successive 

 records. Note great reduction in small cell activity and consequent loss of some 

 follower activity. Large downward spikes in trace p probably originate in large 

 cells which were not dosed with GABA. Time line, 0- 1 sec. 



4 8 \? 



SF(.OfJDS 



Fig. 29. Acceleration of ganglionic activity, time course and spatial summation 

 {Homarus). Ordinate, spontaneous ganglion activity; abscissa, time in seconds. 

 Stimulate accelerator fibers in dorsal nerve at 22/sec. (O), two accelerator fibers 

 respond to each stimulus; (#), one accelerator fiber responds. Note slow growth 

 of acceleration and slow decay to normal activity. Stimulation stopped at end 



(Maynard, 1954). 



