Fluctuations in Neural Tiiresholds 



163 



u 



E 3.0 



AMPLITUDE (-c^) AND LATENCY 

 (-•-)OF N, AS A FUNCTION OF 

 2-5\-|NTENSITY OF CLICK STIMULUS " 



150 



125^ 



-100 -80 -60 -40 -20 



CLICK INTENSITY (dB RE 1.29V ACROSS 



PHONE) 



Fig. 10. Intensity function (open circles). A''i is the first diphasic response com- 

 ponent seen in the traces of Fig. 9. The amplitude measurement is made between 

 the positive and negative peaks of N^. Each plotted point is the median of about 



ten such measurements. 



m 

 o 



o 



o 



in 

 tr 





50 DB 



30DB 





RESTING RESPONSE 



tl -lODB 



12.2 MSC 30MSC 6IMSC 



TIME INTERVAL BETWEEN CLICKS 



Fig. 11. Two-click paradigm: the responses shown are to a constant intensity 

 (—45 dB) second click. The vertical set shows the effect of varying the intensity 

 of the first click; the horizontal set shows the effect of varying the interval 

 between clicks. Upper right: response to a — 45 dB click presented alone. 



From McGiLL (10). 



in each case choose one constant, ^(5*2, At). Fig. 12 shows a number of fits 

 to the data points which were obtained in this way; 5*2 is constant and each 

 curve corresponds to a different value of At. 



In a second group of experiments the standard deviation of a hundred 

 response ampHtudes was computed at each stimulus intensity, and the result 

 was plotted as a function of stimulus intensity. It is readily shown that N 



