INTRINSIC RHYTHMS OF THE BRAIN 285 



EYES SHUT 





ANSWER 





PEAK-TROUGH PERI06 IfflJICATOR 



FIG. 3. Alpha and theta activity in a normal young subject. Records as described for figure 2. 

 The primary records are particularly complex. In the frequency analysis records, the solid lines 

 connect the peaks related to channel 3, while the dotted lines connect the peaks related to channel 

 5. This analysis reveals components in the theta and alpha bands which fluctuate independently in 

 the two hemispheres. During the first half of the record the subject was at rest and the second 

 half was replying to an annoying question. During this phase the theta content increased in the 

 transverse derivation (channel 5) after a period of activation and fluctuation in skin resistance 

 (G.S.R.). The period analysis shows fluctuations in wave intervals between about 100 and 140 msec, 

 corresponding to periods of relative alpha and theta activity. The prolonged theta activity is a char- 

 acteristic of this response to annoyance. 



EYES OPEN 



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FIG. 4. Delta and theta activity recorded from a normal child aged 3. Six primary records (above) 

 and frequency analysis record (below). In early youth these rhythms are characteristically difTusc 

 and complex; the frequency analysis shows almost equal abundance in the range from i .5 to 9 cycles 

 per sec. with a peak in the theta band at 5 cycles per sec. These rhythms are almost unaffected by 

 stimulation. 



