Fig. 2. A KCl stressor enhances LTM formation in Lymnaea. Top, snails (N=20) that received one 30 min training session (TS) of contingent `poking' did not have a significant change in breathing behaviour when tested 24 h later (MT; top). Bottom, snails (N=38) that were exposed to 25 mmoll^–1 KCl for 30–35s before a 30 min TS exhibited memory at 24 h (^**P<0.01). When tested in carrot context (CT) the number of attempted pneumostome openings returned to naive levels (P>0.05), indicating context-specific memory. Snails that received KCl before training and were tested for savings at 48 h did not show memory. [Reprinted from Martens et al. (Martens et al., 2007a), with permission from Elsevier.]