Fig. 3. Previous intermediate-term memory (ITM) training does not negatively affect the ability to form long-term memory (LTM). (A) A cohort of 20 naïve snails received three 15 min operant conditioning training sessions, with each training session separated by a 30 min rest interval. Learning occurred (ANOVA, F19,2=12.1514, P<0.001); session 3 was significantly different from session 1 (P<0.01). Following a 3 h rest interval, these snails received the LTM training procedure, and memory was tested 48 h after the last LTM training session. The number of attempted pneumostome openings in session 4 was not significantly different (NSD, P>0.05) from that in session 3, indicating that ITM was present. The LTM training procedure resulted in no further statistically significant decrease in the number of attempted openings (session 4 was not significantly different from session 6, P>0.05). Memory was present when tested 48 h later because the memory test (MT) was not significantly different from session 6 (NSD, P>0.05), but was significantly different from session 1 (P<0.01). (B) As in A except that the LTM training procedure was initiated 4 h after the last ITM training session. Note that there was a significant difference between the response in session 3 and that in session 4 (P<0.01), indicating that there was no ITM. The previous ITM training did not interfere with the establishment of LTM at 48 h because MT was not significantly different from session 6 (NSD, P>0.05), but was significantly different from session 1 (P<0.01).
