310 



C. EYZAGUIRRE 



Fig. 19. Slow receptor cell. Resting potential 70 mV (unstretched). a (a). Cell 

 under stretch, train of inhibitory impulses at 130/'sec polarizes, a (b). Antidromic 

 impulse (a) alone, a (c). (a) invades cell during inhibitory train which prevents 

 development of complete after-positivity. Dotted Hne indicates expected time 

 course, b (a). Cell relaxed, train of five inhibitory impulses at 200/sec depolarizes. 

 B(b). (a) alone shows no after-positivity. e (c). (o) during inhibition is not 

 appreciably changed. (From Kuffler and Eyzaguirre,y. Gen. Phvsiol. 39 : 155-184, 



1955.) 



depolarization level similar to that produced by the inhibitory potentials 

 would produce an after positivity (this possibility is illustrated in the left 

 column of Fig. 19). This observation indicates clearly that the generator 

 potential is turned off during inhibhion and mainly those parts of the anti- 

 dromic impulse which are Hnked with excitation spread into the dendrites 

 are modified. 



When the antidromic invasion of a cell is unobstructed the overshoot of 

 the action potential is not changed by inhibitory stimulation. If for some 

 reason a partially blocked antidromic impulse reaches the cell, inhibitory 

 activity exerts a very profound effect on the amplitude of the antidromic 

 impulse. This is especially noticeable when the antidromic impulse has been 



