Improved detectability of neuronal connectivity on mechanical sectioning setup by using confocal detection

A recently reported micro-optical sectioning tomography system has great potential to draw the neuronal circuits of large brain volume with submicron resolution by combining fine mechanic sectioning with simultaneous optical imaging. However, sectioning the fluorescence sample sometimes induces tears between adjacent tiles and causes difficulties in continuous fiber tracing from fluorescence imaging. A confocal detection to recover the interruptions of the nerve fiber is introduced. With a 50-μm-width confocal slit, the signal-to-background ratio is increased 16- to 49-fold more than that without the slit, which effectively improves the detectability of the signal in the interruptions and enables continuous tracing of the neuronal circuits.