Figure 1.

Schematic illustration of the 5-CSRTT used in the present experiment. Rat was placed in the center of the chamber. A trial started with the illumination of magazine until rat made a nose-poke response. After a delay (the intertrial interval, ITI), the stimulus light was presented over the hole in pseudorandom order. If an animal respond with a nose-poke into the illuminated hole within a limited hold of 5 s, a pellet was delivered into the magazine. An ITI began when the food pellet was retrieved, with the next stimulus light presented after the ITI. A period of time-out would be followed by an incorrect response with the house-light on for 5 seconds, during which no stimuli were presented. After a timeout, the rat could start a new ITI by nose-poking to magazine. Analyses of measures were based on the formulations as indexed.