Fig. 1. Schematic illustration of the olfactory working memory capacity task.

A Timeline of the novel task. B The non-matching-to-single-sample (NMSS) learning phase of the task. During the NMSS phase, each mouse was presented with two stimuli (sample odour stimulus and novel odour stimulus) per trial and trained to dig for pellets in the scented bowls with novel odours. In each trial, mice were initially placed in the sample chamber and allowed to explore and detect the sample odour. Then, the mice were allowed to enter the choice chamber and choose between the sample odour bowl and the novel odour bowl. C Different types of responses in the NMSS phase. D The non-matching-to-multiple-sample (NMMS) learning phase and capacity-testing phase of the task. During the NMMS phase, the mice were placed in the sample zone to detect the sample stimulus, allowed to enter the waiting zone for 5 s, and then allowed to go through the door to choose between the sample odour bowl and novel odour bowl on the platform. Once the mice performed reliably in the NMMS rule-learning phases, they underwent a WM capacity test. The procedure was similar to that of the NMMS rule-learning phase, except that the number of sample odours that the mice were required to remember was gradually increased until two consecutive incorrect responses were made.