Introduction of the 8-arm food foraging task and performance of normal adult rats.

<p><b>A</b>: Schematic design of the 8-arm food foraging task (8-arm FFT). Horizontal bar shows the sequence of task phases and critical events during a trial. Each rat was placed on the platform with all arm gates closed (before-GO period). Two to three minutes later, all gates were opened (GO), allowing free access to the tip of each arm, where the reward was located in a food cup. Five minutes after the last-reward collection (LRC), the rat was removed and placed in its home cage. Bottom row of diagrams in (A) shows movement traces during the different phases. Each of the solid, irregular lines shows a typical example of well-trained rat movements (41st–45th trials). Repeated training produced a pattern of reliable and low-cost behavior, which was characterized by automatic-appearing sequential arm selection before LRC. After the LRC (reward-<u>un</u>available period), random patterns were common, with much slower running speeds compared to before the LRC. <b>B</b>: Timing of changes in mean tip-approaching (TA, black filled bars) and platform-approaching speed (PA, open bars) of well-trained rats (41st–45th trials). The platform-approaching speed at the 8th approach (just after LRC) was significantly slower than that of the 7th approach (one-way ANOVA, <i>F</i>_11,156 = 100.8, <i>P</i><0.05; Dunn-Sidak test, * <i>P</i><0.05). Similar to platform approaching, a significant slowing of tip-approaching speeds occurred between the 8th and 9th approaches (<i>P</i><0.05). Dashed line shows at which point the LRC occurs. <b>C</b>: Change in the number of arm re-entry errors before LRC (reward-available period). <b>D</b>: Change in average tip-approaching and platform-approaching speeds before LRC. <b>E</b>: Change in the number of arm re-entry errors for one minute after LRC. <b>F</b>: Change in traveling distance for one minute after LRC. The various experimental groups are explained in detail in the Supplementary Methods. Error bars denote SEM.