566 MAKOTO SATO, GEORGE AUSTIN, AND WALTER STAHL 



/ /^ 



800 r — *- ^ 



3200r 



A. 



■< 



^ N,s^ ^ '600- 



U,^^ ^^ 2400r 



a 



4200r 



5000r 



6000r 



Control 



3850r 

 I3min 

 8970r 

 38 min 



I4090r 

 58min 



—>' I39nnin 



I92min 



/~ Control 



3850r 

 I5nnin 



8970r 

 40min 



I4090r 

 I35min 



I69min 



200min 



2IOmin 



2l5min 



B 



Fig. 4. (A) Antidromic extracellular responses from motoneuron during exposure 

 to radiation. This observation was done within 1 hour after initial irradiation. Upper 

 vertical bar represents 2 mv; the lower, 20 mv. Horizontal bar is 2 msec. (B) Extra- 

 cellular response from motor neurons during and after successive irradiation. Left and 

 right columns are antidromic and orthodromic responses, respectively. Vertical and 

 horizontal bars represent 1 mv and 2 msec, respectively. Total doses and time from 

 the initial irradiation are shown. 



