Figure 1

Inhibition of [Ca ²⁺ ]i increase using BAPTA-AM blocks long-term memory formation. Acquisition and retention performances following an injection of BAPTA-AM 500 μM, an intracellular Ca²⁺ chelator, or saline 1 h before training. A. Percentages of conditioned responses (%CR) increase during the three conditioning trials (C1, C2 and C3) for the control group (n = 70, Q = 60.0, P < 0.001) and for the BAPTA-AM group (n = 85, Q = 81.0, P < 0.001), without any difference between groups (U = 278.5, P = 0.93). Response to the conditioned stimulus (CS) after 72 h was significantly lower in the BAPTA-AM than in the control group (χ² = 9.1, P = 0.0026). Moreover, bees responded significantly more to the CS than to the new odor in the control group (χ² = 24.3, P < 0.001) but not in the BAPTA-AM group (χ² = 2.0, P = 0.15). Consequently, specific response proportion (% individuals responding to the CS and not to the new odor) was significantly lower for BAPTA-AM than for control bees (χ² = 15.55, P < 0.001). Furthermore, control and treated animals responded similarly to the new odor (χ² = 2.25, P = 0.13). B. The percentage of specific response (% SR) at 3 h (Control: n = 125; BAPTA-AM: n = 120) and 24 h (Control: n = 112; BAPTA-AM: n = 117) were not affected by treatment with BAPTA-AM (respectively: χ² = 0.65, P = 0.42 and χ² = 0.43, P = 0.51). The % SR presented at 72 h corresponds to the data of Figure 1A. (***: P < 0.001, NS: non-significant).