Fig. 5: Simultaneously recorded calcium response amplitudes in PC dendrites and AIS are correlated during PF stimulation.

a Schematic of microelectrode placement to apply electrical stimuli to a bundle of PFs while two-photon imaging was performed in the sulcus of lobule Crus I, where PCs lie horizontal to the imaging plane. This allowed the dendrite, soma, and AIS of each PC to be captured within a single field of view. The blue shaded area represents the two-photon image plane, which yields a calcium image such as that shown in (b). b Representative two-photon images of the dendrites, soma, and AIS of each PC captured by a single field of view. Arrowheads point to the AIS. The schematic diagram shows PF stimulation using a microelectrode to generate a calcium response. Calcium imaging followed the same protocol as for PF-RF experiments (Fig. 1). Scale bar is 50 μm. Mean ± SEM of spontaneous calcium events (c) and evoked responses (d) of 41 cells from 5 mice. The black arrowhead in (d) indicates a suppression of AIS calcium signals following the initial response. e–h Maximum values of somatic and axonal calcium transients plotted against the maximum values of dendritic signals within the time window of 0–200 ms after the initiation of the rising phase and stimulus for spontaneous events (e, f) and evoked events (g, h). Lines represent the linear regression fit, with R indicating the Pearson correlation coefficient and p indicating its significance.