FIGURE 9.

Impaired locomotor activity and recognition memory in NCmahTg mice (5–6 months old). A, open field test. Locomotor activity for 2 h was plotted as beam breaks (traveled distance) per 10 min. Open circles, NCmahTg mice; filled circles, control (Cre-positive (no Cmah transgene)) mice. Data are shown as the means with S.E. The difference between control and NCmahTg mice was statistically significant when analyzed by two-tailed paired t test (p < 0.001). B–D, Barnes Maze test. Mean time to enter the escape box (B) and mean number of errors (C) were shown for 9 days of trials. On day 10, the escape box was removed, and time spent in each quadrant (target quadrant where the escape box was originally located and other three quadrants) was measured (D). Data are shown as the means with S.E. Open circles, NCmahTg mice; filled circles, control (Cre-positive (no Cmah transgene)) mice. E and F, novel object recognition test. During two trials, two identical objects were placed in the testing chamber. Fifteen min later, one of the familiar objects was replaced with a novel object, and the duration of contact was measured. The result was shown as mean duration of contact (E) and recognition index (F) with S.E. Recognition index was calculated using the following formula: recognition index = (time exploring novel object/time exploring all objects) × 100. The difference in recognition index between control and NCmahTg mice was statistically significant when analyzed by two-tailed unpaired t test. G, fear-conditioning test. Freezing behavior in each session was measured. Sessions: Habituation, conditioning chamber before conditioning; Context, trained chamber without the cue (light and tone); Pre-Cue, trained chamber with an altered context without the cue (light and tone); Cue, trained chamber with an altered context and cue (light and tone). Data are shown as the means with S.E. Control, Cre-positive (no Cmah transgene); Tg, NCmahTg. n = 10 (control) or 16 (NCmahTg).