[Imaging of spatiotemporal pattern of synaptic inputs during memory replay]

Dendrites receive excitatory synaptic inputs from upstream cell ensembles to trigger action potentials at the cell body. The efficiency of excitatory synaptic inputs on neuronal output depends on the spatiotemporal pattern of synaptic inputs. However, technical limitations still make it unclear how synaptic inputs are organized along dendrites in both space and time. Spine calcium imaging, which records synaptic inputs as calcium transients at individual spines using calcium ion-sensitive fluorophores, is a unique method for studying the spatiotemporal patterns of synaptic input. We developed a functional multiple-spine calcium imaging (fMsCI) that combines whole-cell patch-clamp recording and spinning-disk confocal imaging to observe hundreds of synaptic inputs simultaneously. Using this method, we discovered sequential synaptic inputs that accompanied sharp wave ripple oscillations. In this review, I will discuss the function of sequential synaptic inputs and the potential uses of fMsCI to better understand neurological disorders.