122 



in a multiple schedule, and not when FR occurred alone or as part of a nultiple 

 fixed-interval fixed-ratio schedule, the nicotine-induced rate Increases were 

 most likely due to an interaction between the water and shock conditions main- 

 taining response. 



H- NICOTI NE 0.8 mg /kg 



' ^ 



O 120-j BEFORE 



LU 



1 



UJ 



2 



120 H AFTER 



100- - 



• INITIAL 



« DAY 31 



o REDETERAAINATION 



SUCCESSIVE SIX-MINUTE SEGMENTS 



