FRANK MORRELL 



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Fig. 6 

 Bilateral cortical isolation in an animal with well-developed independent mirror focus. This 

 is the same animal shown in Fig. 3. Recordings were made with the animal under 40 mg. per 

 kg. of nembutal anaesthesia. Derivations are from the electrodes indicated in the diagrams. 

 Isolation of the primary lesion is first carried out (6A) and demonstrates loss of paroxysmal 

 spike discharge in the primary region while the secondary area continues to discharge actively. 

 Isolation of the secondary region was then undertaken (6B and C). For a few moments 

 abnormal discharge persists in the isolated secondary region (B) but soon disappears (C) to be 

 replaced by almost complete electrical silence. Note that the electrode positions have been 

 changed in B and C. Calibration: 50 microvolts and i second. 



