Fig. 1.

Beams of activated PFs in sagittal and transverse slices, imaged from the detected change in [Ca²⁺]_i. (A) Fluorescence image from a sagittal slice from a GCaMP2 mouse. The molecular layer (ML) exhibits more fluorescence than the granular layer (GL) and the Purkinje cell layer (PCL). The site of stimulation with a monopolar electrode is shown in red. (B) ΔF/F image of the same slice showing the transient change of GCaMP2 fluorescence (indicating a transient [Ca²⁺]_i rise) following double-pulse stimulation. (C) Radial profile of ΔF/F signal from a beam of activated PFs obtained with wide field fluorescence microscopy (red line) or with confocal microscopy (black line). Deconvolution (see “Experimental procedure”) of the signal obtained with epifluorescence microscopy provided a ΔF/F signal (green line) with a radial profile similar to the signal obtained with confocal microscopy. (D) Same ΔF/F image as in (B), deconvolved. (E) 3D representation of the ΔF/F signal shown in (D). (F) 3D representation of the ΔF/F integrated area (ΔF/F integrated over the sagittal plane and divided by ΔF/F maximum) calculated for image in (D, E). The integrated area was used to define the section of the beam of activated PFs (see “Experimental procedure”). (G) Fluorescence image from a transverse slice from a GCaMP2 mouse. (H) ΔF/F image of the same slice showing the transient change of GCaMP2 fluorescence following double-pulse stimulation at the site indicated in (G). (I) Averaged diameter of the beam sections for stimulations in sagittal slices (Sag, n = 41) or in transverse slices (Trans, n = 25). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)