Cortical ECM density
The luminance ratio of the cortex sides ipsi- and contralateral to the trauma or sham trauma ear was assessed in the T, NT and C groups with a two-factorial ANOVA with the factors side and group . We found (Figure 2 ) a significant group effect (F(2, 114)=7.05, p=0.001) with the mean luminance ration of the T animals’ brains (0.85 ± 0.03) being significantly higher than those of the NT (0.71 ± 0.03, Tukey post-hoc tests: p=0.001) or sham control brains (0.72 ± 0.04, Tukey post-hoc tests: p=0.035). Neither in thecortex side (F(1, 114)=0.02, p=0.89) nor in theinteraction analyses (F(2, 114)=1.03, p=0.36) a significant effect could be found in this analysis. So this first analysis points to a general increase in luminance ratio and therefore in ECM density in the auditory cortex of animals with behavioral signs of tinnitus.
When we investigated the two hemispheres separately (and corrected for repeated testing), we found that the described significant ECM density (i.e., luminance ratio) increase in T animals could be found only in the auditory cortex contralateral to the trauma (Figure 2 ): There, the one-factorial ANOVA (F(2, 57)=6.65, p=0.002) revealed a higher ECM density (T: 0.88 ± 0.04; NT: 0.68 ± 0.04; C: 0.71 ± 0.06) with a significant Tukey post-hoc test between T and NT with p=0.002 and a tendency for a higher tinnitus related ECM density between T and C with p=0.08; no difference was found between NT and C with p=0.88. On the cortex side ipsilateral to the trauma, no significant differences (F(2, 57)=1.47, p=0.24) were found between the ECM density of the three animal groups (T: 0.83 ± 0.04; NT: 0.74 ± 0.04; C: 0.72 ± 0.06); also the Tukey post-hoc tests did not show any significant differences.