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. Author manuscript; available in PMC: 2012 Nov 14.
Published in final edited form as: Brain Res. 2011 Sep 22;1423:17–29. doi: 10.1016/j.brainres.2011.09.033

Table 1.

Group designations and summary of procedures

Group Designation Conditioning Extinction3 30-day SR test4 Number of rats5
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Odd Days Even Days
CS-Only Extinction (CSO-EXT) SAC1+LiCl2 Water SAC+LiCl Water SAC+LiCl Water SAC Water + SAL SAC 12/6/6
Explicitly Unpaired Extinction (EU-EXT) SAC+LiCl Water SAC+LiCl Water SAC+LiCl Water SAC Water + LiCl SAC 11/5/6
No Extinction (NE) SAC+LiCl Water SAC+LiCl Water SAC+LiCl Water Water Water + SAL SAC 16/9/7
1

SAC = 30 min presentation of the 0.3%, weight by volume, saccharin salt solution. The SAC was dissolved in deionized water and presented to animals in a single bottle test.

2

LiCl = Injection of lithium chloride (81 mg/kg; 1 ml/kg; i.p.), dissolved in physiological saline.

3

Extinction = EU-EXT refers to the method in which SAC and LiCl were administered to animals on alternate days throughout the extinction phase of the study. SAC was administered every-other day to animals designated as CSO-EXT, but physiological saline (SAL, i.p.) injections were administered in lieu of lithium chloride, as a control measure, on water-only days. Note that animals in the NE group were never given extinction training, but were instead given only water throughout this phase of the study to parallel the fluid presentation schedule of the other groups. However, NE rats were offered SAC on the day their yoked counterpart reached asymptotic extinction. SAC offerings were followed by 30-min supplemental water presentations to reduce the chance of dehydration. There was never any indication that EU-EXT rats formed an aversion to water.

4

SR Test Solution = All animals received water only for 29 days and on the 30th day all received 0.3% SAC solution as the SR test solution. Note that for animals in the NE group this was not a true test of SR, but simply a final CS re-exposure to establish the strength of the CTA prior to sacrifice.

5

The first number indicates the total number of rats in each group. The second number represents the number of rats that were sacrificed following asymptotic extinction. The third number represents the number of rats sacrificed following the spontaneous recovery test.