Figure 1.

Localized, spontaneous dendritic calcium transients. (a) Fluorescence image of a neuron. Fluo-3 was loaded into the cells by using the AM form of the dye, which accounts for the labeling of processes in the background (including astrocytes). The region enclosed by the rectangle is shown in b. (b) A scan line through the lower dendrite was chosen for fast imaging in the line-scan mode (4 ms per line). (c) Fluorescence changes in two regions indicated by 1 and 2 in b, plotted against time. Spontaneous increases in fluorescence intensity were observed independently at sites 1 and 2. Fluorescence intensity is in arbitrary digital units resulting from conversion of the photomultiplier output to numbers from 0 to 255.