“…For example, fMRI provides an excellent aid for the study of psychiatric disorders [ 3 , 4 ]. However, for dynamic observation of neuronal and synaptic activities at the single-cell level down to molecular scales, craniotomy experiments are frequently required for implantation of cortical and deep-brain electrodes or electrode arrays [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. For two-photon experiments and fluorescence measurements, cranial surgery is also performed in installation of many novel brain-computer-interfaces (BCIs) [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ].…”