Fig. 4. Immediate cooling after the one-trial conditioning procedure blocks long-term memory (LTM) formation. (A) Snails (N=60) were subjected to the one-trial conditioning procedure and were then immediately (within 30 s) cooled to 4°C for 30 min. After cooling, snails were kept at room temperature and tested 1 h (N=30) and 24 h (N=30) later. There were no significant differences in the response to the conditioned stimulus (CS) following conditioning and the immediate cold block (one-way ANOVA). (B) Feeding response to the CS following the one-trial conditioning procedure after delayed cooling. Snails were cooled as in A except that the cooling was delayed until after the 10-min memory test. That is, rather than immediate cooling, cooling was delayed for 11 min. In this experiment we classified 20 snails as good performers (filled squares) and 10 (open squares) as poor performers. The bar below the graph indicates the cooling period. The x axis has a logarithmic scale. The differences between the feeding response of the good performers and that of the poor performers were observed for at least 24 h (*P<0.01, Student's t-test). All values are means ± s.e.m. These data show that the necessary new protein synthesis required for LTM is initiated within 10 min of conditioning.