Table 2.

Inactive lever responses during Cycle I.

JVSA Group	Saline		Nicotine
	Adolescent-onset	Naive Adult-onset	Adolescent-onset	Naive Adult-onset	Pre-exposed Adult-onset
Week 1	75.0 ± 15.1#	21.6 ± 4.6	137.6 ± 30.2#	20.8 ± 3.1	30.3 ± 4.6
Week 2	39.4 ± 11.3#,‡	10.5 ± 2.1‡	119.9 ± 34.4*,#	7.9 ± 1.7‡	7.7 ± 1.6‡
Week 3	24.6 ± 6.6#,‡	10.0 ± 2.7‡	57.1 ± 15.3#,‡	8.1 ± 1.l‡	7.8 ± 1.5‡
Extinction	N/A	N/A	21.0 ± 7.0‡	10.3 ± 1.9‡	8.7 ± 2.6‡

^*Denotes significant group differences from saline IVSA.

^#Denotes significant group differences from naïve adults.

^‡Denotes significant differences from Week 1.