## 3 Results
### Music-Induced OBBB Stimulates Clearance of FaS from the Mouse Brain  
Next, we investigated how OBBB changes the movement of Fa\(\beta\) in CSF. Figure 1c,d illustrates the real-time fluorescence microscopy of fast Fa\(\beta\) spreading from the ventricle to the subarachnoid space in mice with IBBB and OBBB. The intensity of the fluorescent signal was monitored immediately after Fa\(\beta\) injection into the right lateral ventricle of mice from both groups. Our results show that mice with OBBB vs. mice with IBBB demonstrated a higher fluorescent signal from Fa\(\beta\) on the brain surface. [PERSON] et al. showed a characterization of time-dependent CSF flow routes within the mouse cranium [43]. They clearly demonstrated that after intraventricular injection, the tracer distributes from the dorsal to ventral aspects of the brain. Based on these facts, in the next step, we analyzed a delayed distribution of Fa\(\beta\) 1 h after its injection in the ventricle using ex vivo fluorescence microscopy. Figure 1e-h illustrates that mice with OBBB vs. mice with IBBB demonstrated faster distribution of Fa\(\beta\) from the dorsal to lateral aspects of the brain. Indeed, the intensity of the fluorescent signal from Fa\(\beta\) was 2.3-fold lesser on the dorsal aspect of the brain (0.11 \(\pm\) 0.03 a.u. vs. 0.25 \(\pm\) 0.03 a.u., \(p<\) 0.001) and 3.5-fold higher on the ventral part of the brain (0.42 \(\pm\) 0.01 a.u. vs. 0.12 \(\pm\) 0.02 a.u., \(p<\) 0.001) in mice with OBBB vs. mice with IBBB (Figure 1q). These data suggest that OBBB contributes to the distribution of Fa\(\beta\) from the ventricle to the area of location of the basal MLVs playing an important role in the brain drainage [5; 6; 43]. Figure 1i shows the perivascular pathway of Fa\(\beta\) spreading. Notice that perivascular and paravascular routes are considered as the crucial pathways of fluid drainage and clearance of toxins from the brain [1; 2; 3; 4; 44]. We also observed lymphatic clearance of Fa\(\beta\) from the mouse brain that was faster in mice with OBBB than in animals with IBBB. Figure 1j illustrates the presence of Fa\(\beta\) in MLVs that we observed in both groups. This fact suggests that MLVs are pathway of clearance of Fa\(\beta\) from the brain and confirms results of others [7; 11] (Figure 1j). However, mice with OBBB demonstrated a stronger intensity of signal from Fa\(\beta\) in the meninges than in mice with IBBB (Figure 1k,l). The dcLNs are the first anatomical station of CSF exit from the brain and the place of accumulation of molecules, which move from the CNS [5; 7; 23]. As shown in Figure 1m,n,q, the accumulation of Fa\(\beta\) in dcLNs was higher in mice with OBBB vs. mice with IBBB.  
Next, we analyzed the distribution of Omniscan after its injection in the cortex in mice with IBBB and OBBB using real time MRI imaging during 2 h. Figure 1o,p,r demonstrates that the MRI signal from the contrast agent was 2.1-fold higher in mice with OBBB vs. mice with IBBB (3.20 \(\pm\) 0.03 a.u. vs. 1.47 \(\pm\) 0.05 a.u., \(p<\) 0.001).  
Altogether, these results suggest that OBBB increases the movement of Fa\(\beta\) in CSF and lymphatic clearance of Fa\(\beta\) from the brain.