Fig. 3

a Time spent in the outer and inner zones of the open-field arena, b lines crossed in the first 30 s, c rearing, and d total lines crossed by 2, 4, and 8-week swimming rats. Naïve rats were age-matched, and were housed separately in their cages without exposure to unnecessary handling or any stressful conditions (i.e., not being placed in the water-filled chamber). All results were obtained from the open-field test. F values and degree of freedom values are also presented for each behavioral datum. *P < 0.05 compared with 2-week swimming group. ^† P < 0.05 compared with 4-week swimming group. Numbers in parentheses represent the numbers of animals