Control Data. Slices were cultivated for 14 days before being subjected to TBI introduced by a stylus dropped onto the CA1 region. Slices were then incubated in an atmosphere of 95% air and 5% CO2. Negative control group slices were treated the same way, except for the trauma. After 72 h trauma intensity was assessed by fluorescence imaging and pixel based analysis. The fluorescence intensity corresponded to the trauma intensity of each pixel and was broken down to a value between 0 and 255. The histogram shows the distribution of pixels for the different fluorescence intensities for the negative control group (n = 35, labelled a) and the slices of the positive control group (n = 185, labelled b). The middle line represents the mean for each fluorescence value; the upper and lower lines represent the upper and lower boundaries of the SEM. The interrupted vertical line is the applied threshold at a grey scale value of 100. The sum of all pixels beyond this threshold was calculated for each group and served as a measure for trauma intensity. Above the graph, example images for the negative control group (left) and positive control group (right) are shown. The insert in the upper right corner represents the trauma levels of both control groups normalized to the positive control group.