Table 2.

Extinction Responding in Group-Housed and Socially Isolated Long- Evans Rats^a

	Group Housedb	Socially Isolated	Statisticsc
Ethanol Self-Administration
Total Lever Responses	123.3 ± 9.1	127.8 ± 12.5	n.s.
Response Bouts	9.2 ± 0.9	9.1 ± 0.6	n.s.
1st Bout Responses	15.7 ± 4.6	33.4 ± 8.9	n.s. (P<0.1)
1st Bout Response Rate (press/min)	28.5 ±4.4	54.7 ± 11.4	t=2.13, P<0.05
Response Latency (sec)	26.4 ± 6.1	45.2 ± 6.2	t=2.09, P<0.05
Sucrose Self-Administration
Total Lever Responses	141.8 ± 9.6	141.0 ± 20.0	n.s.
Response Bouts	4.2 ± 0.8	4.8 ± 0.9	n.s.
1st Bout Responses	30.3 ± 11.9	24.7 ± 8.3	n.s.
1st Bout Response Rate (press/min)	5.6 ± 0.3	6.1 ± 0.3	n.s.
Response Latency (sec)	40.5 ± 9.6	36.4 ± 9.2	n.s.

^aExtinction responding was measured with two separate individual trials separated by a week of standard self administration. Averages for individual animals were used for the group comparisons.

^bFor the ethanol self-administration study, n=11 for the group housed animals and n=16 for the socially isolated animals (see text). For the sucrose self-administration study, n= 11 for both the group housed and socially isolated animals.

^cStatistical comparisons were made using Student's t-test. P<0.05 was considered significant. “n.s.” = not significant