Representative swimming tracks.

<p>A) Tracks of finding the hidden platform in rats on the fourth day of training in the navigation test. The diagram of the tracks shows that the control rats more easily found the platform, whereas the rats in the fluoride, arsenic, and fluoride + arsenic groups found the platform through repeated exploration. Red circle: hidden platform; black line: swimming tracks. B) Tracking pictures in the 120 s probe trial test on the fourth day in rats. The diagram of the tracks indicate that the control rats repeatedly passed through the region where the original hidden platform was located, whereas the rats in the fluoride, arsenic, and fluoride + arsenic groups passed through the region of the platform only a few times.