All-optical observation on activity-dependent nanoscale dynamics of myelinated axons
Junhwan Kwon, Sungho Lee, Yongjae Jo, Myunghwan Choi
Abstract
Significance: studies have suggested that neural activity accompanies nanometer-scale cellular deformations, whether neural activity can dynamically remodel the myelinated axon has remained unexplored due to the technical challenge in observing its nanostructural dynamics in living tissues. Aim: We aim to observe activity-dependent nanostructural dynamics of myelinated axons in a living brain tissue. Approach: We introduced a novel all-optical approach combining a nanoscale dynamic readout based on spectral interferometry and optogenetic control of neural excitation in an acute brain slice preparation. Results: In response to optogenetically evoked neuronal burst firing, the myelinated axons exhibited progressive and reversible spectral redshifts, corresponding to the transient swelling at a subnanometer scale. We further revealed that the activity-dependent nanostructural dynamics was localized to the paranode. Conclusions: Our all-optical studies substantiate that myelinated axon exhibits activity-dependent nanoscale swelling, which potentially serves to dynamically tune the transmission speed of neural information.