One week after arrival, between 3 and 4 weeks of age, rats started their cognitive training in the operant chambers. Prior to response training, a handful of reward pellets was provided to the rats in their homecage to reduce potential food neophobia. In the first training step, called habituation, the rats were introduced to the chamber and were provided with 25 reward pellets randomly delivered into the feeder magazine over the course of 30 min. The second training step consisted of autoshaping (AT), during which a conditioned stimulus (white circle, diameter 8 cm) on the right side of the touchscreen was introduced and associated with reward delivery. In this step, the rat received the reward either upon touching the image or when the 30 s stimulus presentation passed independently from whether the rat touched the screen or not. Each 30 min session consisted of 50 trials, and to continue to the next training stage, certain criteria had to be met (Table 1 ). After a correct response, one reward pellet was provided, the stimulus disappeared, and an inter-trial interval of 5 s followed. In the third step, defined as must touch (MT), rats were required to press the circular stimulus on the screen to obtain the reward, and a new trial would start only after the pellet was collected from the feeder magazine. An incorrect response or no response (omission) resulted in no reward delivery. In the next step, called punish incorrect (PI), a negative reinforcement was introduced. When the rat pressed the screen on the wrong location or in the absence of any stimulus presented, the house light turned on (illumination of the house light for 10 s), and no pellet was delivered. The last step of the training stages consisted of what is defined as moving punish incorrect (MPI), during which the stimulus changed position within the left and right aperture of the mask in random order.
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