In this and in subsequent figures, values from measurements obtained during the inactive and active phases are respectively shaded and unshaded. In this and subsequent figures, upper bars show the time to stop responding. Lower bars show the percent change in the response (-((Train-Test)/Train)*100), which is a measure of memory. In all figures standard errors are shown. Experiments in this figure were performed on the diurnally active A. californica. (A) Blocking protein synthesis during the sleep phase blocks 24 hr memory. Animals were trained during their active phase (day), and were tested 24 hr later. 12 hr after training, during the sleep phase, animals were injected with ASW (N = 9) or with 10 µM anisomycin (N = 12). (1) There is a significant decrease in the time to stop responding to the food during the 24 test (p=0.02, t = 2.76, df = 8; two tailed paired t-test), indicating memory. (2) There was no significant difference between time to stop responding during the original training, and the test 24 hr later (p=0.21, t = 1.34, df = 11; two tailed paired t-test), indicating that block of protein synthesis in the sleep phase following training blocks memory consolidation. (3) In addition to consolidation that follows training (not shown), a second phase of consolidation occurs during sleep. This phase is blocked by the translation blocker anisomycin, preventing the expression of long-term memory. (B) Training during the sleep phase is ineffective in causing long-term memory. (1) Training animals during the sleep phase (N = 5) did not lead to long-term memory, as shown by a lack of savings when animals were tested 24 hr later (p=0.3, t = 1.12, df = 4; two-tailed paired t-test). In this experiment, animals were treated with ASW just before the training. (2) Memory after training during the active phase is expressed during the sleep phase (N = 11), as shown by a significant reduction in the time to stop 36 hr after training, when animals are tested during the inactive phase (p=0.013, t = 3.03, df = 10; two-tailed paired t-test with Bonferroni correction). (3) A diagram showing that training during the sleep phase is ineffective in producing memory. (C) Effect of a brief recall during the sleep phase. (1) A 3 min training during the sleep phase (N = 7), which is an effective means of recalling a memory, leaves the memory intact (p=0.001, t(6) = 6.02, two-tailed paired t-test). (2) A 3 min training paired with 10 µM anisomycin (N = 6) rescues the memory that would have been blocked by the anisomycin alone (p=0.004, t(5) = 5.01, two-tailed paired t-test). (3) A flow diagram showing that the anisomycin does not block memory formation when followed by a brief training.