Erasure of memory via ZIP infusion into GC emerges across the 2 d after training. a, ZIP (1 μl; 10 nmol bilaterally) or vehicle control (1 μl; PBS bilaterally) was infused to GC 24 h (ZIP, n = 4; vehicle, n = 3) or 36 h (ZIP, n = 4; vehicle, n = 3) after CTA training (30 min of 0.1% saccharin consumption that was followed by 0.15 m LiCl, 2% body weight, i.p.). When tested for CTA memory 48 h after training by comparing saccharin consumption between CTA training day and retrieval trial, both the ZIP and vehicle groups had comparable CTA memory. When animals were infused (ZIP, n = 8; vehicle, n = 7) 48 h after training and tested 24 h later, only the control group learned, indicating that CTA memory was erased. b, CTA sensitivity to ZIP emerges between 43 and 45 h after memory acquisition. Comparison of CTA memory (expressed as the difference in saccharin consumption between CTA training and retrieval trial groups) after ZIP injection at different time points is shown. All data points are taken from a. *Significant difference according to t test or ANOVAs (p < 0.05). See text for further details on statistics.