Figure 6.

Submersion can extend the memory for extinction training. Forty-two animals received three 45 min operant conditioning sessions (TR1 and TR2 were administered on the same day 1 hr apart, followed by TR3 the next day). One hour later, animals received three 45 min extinction sessions (E1 and E2 were administered on the same day 1 hr apart, followed by E3 the next day). The animals were then divided into three groups (n = 14 each). A, The first group received two tests for savings (TS1 and TS2): one at 2 hr after E3 and one at 24 hr after E3. Memory for extinction training was demonstrated at TS1; TS1 was significantly different (p < 0.01) from both TR1 and TR3, thus not meeting the criteria for operant memory designation. Spontaneous recovery for the memory of operant conditioning was demonstrated at TS2; TS2 was significantly lower (p < 0.01) than TR1 and not significantly different (p > 0.05) from TR3, thus meeting the criteria for operant memory designation. B, The second group was immediately submerged after E3 and only taken out for the two tests for savings: one at 2 hr after E3 and one at 24 hr after E3. Memory for extinction training was demonstrated at both tests for savings; TS1 and TS2 were both significantly different (p < 0.01) from both TR1 and TR3, thus not meeting the criteria for operant memory designation. C, The third group was submerged immediately after E3 and only taken out for a test for savings at 24 hr after E3. These animals demonstrated memory for extinction training; TS was significantly different (p < 0.01) from both TR1 and TR3, thus not meeting the criteria for operant memory designation (ANOVA; F_{(41, 6)} = 36.8938; p < 0.0001).