Figure 4.

(A) Computer printouts of the eight superimposed swimming trajectories (first 5 s of each trial) for a typical control rat, a typical irradiated rat, and the best-performing (IR01) irradiated rat. Note that the control rat on the day of change (day 4) swam more toward the previous position of the platform. Their trajectories were somewhat dispersed on day 5, becoming more compact and efficient again by day 8. The dispersed trajectories of the typical irradiated rat were barely affected by the change in platform location on day 4, whereas the heading direction of the best-performing irradiated rat (IR01) was also largely unaffected by the change. (B) Average latency to find the platform on successive days of retraining before and after the platform location was changed to northwest-northeast on day 4 (indicated by arrow). Note that the latency of the control (CO) group almost doubled on day 4, but that no noticeable increase was observed in the irradiated (IR) group.