Figure 6.

Changes in AIS length after sensory deprivation. Graph in (A) shows results for neurons in layer II/III (light gray) and V (dark gray); all other graphs indicate layer II/III data only. (A) Mice were placed in complete darkness from P21 to 28, showing no change compared to P28 control. Sensory deprivation from P14 to 28 resulted in a significant AIS length increase compared to P28 control. Likewise, dark rearing from birth to P28 resulted in a significant AIS length increase compared to P28 control. (B) Box plot comparison of AIS length percentiles and median in each experimental group revealed that juvenile AIS at P15 and before have a wider distribution of individual lengths. At the age of shortest AIS length (P28), AIS length distribution is the narrowest. Dark rearing from birth to P28 results in a similar length distribution as in juvenile AIS at P15. Adult AIS (>P55) show less width in length distribution, but are not as homogeneous as AIS at P28, the phase of highest compression. Vertical bars indicate upper 10% and lower 90% distribution, dots upper 5% and lower 95% percentile. Horizontal bars delineate the median. (C–C₄) Size frequency histograms of various age groups under control and sensory deprivation conditions. (C) Wide distribution of AIS lengths at the peak of juvenile AIS length increase at P15. (C₁) Narrow AIS length distribution at P28 when AIS are shortest. (C₂) Sensory deprivation for 1 week and after eye opening has no effect on AIS length distribution compared to P28 controls. (C_{3, 4}) Under sensory deprivation for at least 2 weeks, mature AIS had a broader length distribution and resembled the developmental P15 peak as shown in (C). ^*p ≤ 0.05, standard deviation.