Remote effect of surgery and phenotype on memory. Five months after surgery, immediately following the last session in the spatial reference test (described in Figure 4), rats were returned to the Morris Water Maze in which the submerged platform had been removed. The probe trial consisted of measuring the % of time spent within a 60 s epoch, in the quadrant in which the platform formerly resided; this is referred to as dwell time in target quadrant. In addition, the time spent in the opposite quadrant, clockwise quadrant (CW), and counterclockwise (CCW) quadrant were also measured. Each quadrant’s data were analyzed separately with two-way ANOVA followed with post hoc analyses, and results are expressed as mean and SD (n = 6). For the target quadrant, there was a significant interaction between strain and surgery (P = 0.04) and the dwell time was significantly lower (* P < 0.01) in the LCR surgery rats than for either the HCR surgery or LCR sham groups. For the opposite quadrant, there was a significant strain and surgery effect (P = 0.003 for the surgery, P = 0.04 for the strain and P = 0.12 for the interaction) and the percent of dwell time in the LCR surgery rats was significantly higher in LCR sham rats (* P < 0.01). The four groups spent similar time in CW and CCW quadrants. HCR = high capacity runner phenotype; LCR = low capacity runner phenotype; surg = surgery.