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 WEEK 1 



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 WEEK 2 



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 WEEK 3 



E A B A 



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Figure j. Persistence of tolerance to the effects of 0.8 mg/kg of nicotine on 

 FR 32 response rates following cessation of chronic dosing- 

 Response rates are from the total 30 minute session (top) and from 

 the first six minutes of the session (bottom). The before group (B) 

 had received nicotine chronically before the session; the after 

 group (A) had received nicotine chronically after the session. The 

 weekly testing sequence was baseline (Wednes day). saline^Thursday) 

 and nicotine (Friday). Data are as percentage of respective control 

 mean, indicated by 100% on the ordinate. Control for the saline 

 (SAL) was the proceeding baseline session. Control for nicotine 

 (NIC) was the mean of the preceeding baseline and saline sessions. 

 The points to the left indicate the initial acute effects of 0.8 

 mg/kg of nicotine. Vertical lines indicate 1 S.E. 



