Figure 6.

Cluster and correlation analysis of spontaneous Bergmann glia (BG) and Purkinje cell (PC) activity. (A) A representative time-averaged frame obtained from the PC layer of one mouse. Two large PCs are depicted (∼18 μm in diameter), each surrounded by four smaller BG cell bodies (large and small dashed and dotted circles). (B) Pseudocolored clusters in which colors denote areas of clustered activity. A propagating spontaneous glial Ca²⁺ wave (cyan field) enveloping a PC, as well as a spontaneously active PC (red spot), is visible. The PCs of interest are indicated by ‘p'. (C) dF/F₀ traces over time obtained from the spontaneously active BG comprising the glial wave (blue, green, red, and light blue lines) and from the PC the wave enveloped (black line) in (A) (top part, red dashed circles). Purkinje cells encountered by propagating glial Ca²⁺ wave did not always respond to surrounding BG activity; when they did so, the PC response was only a small fraction of the spontaneous BG activity. Purkinje cells did not initiate waves as BG responded before PCs (insert). (D) A correlation plot shows dF/F₀ values from the yellow PC in (A) plotted against dF/F₀ values averaged across all yellow BG in (A). There was a small but significant positive correlation (R²=0.29529, P<0.001). (E) dF/F₀ traces over time obtained from the spontaneously active PC (black line) and surrounding BG (blue, green, red, and light blue lines) in (A) (bottom, red dotted circles), showing that spontaneous PC activity did not spread into BG. (F) A correlation plot showing dF/F₀ values from the red PC in (A) plotted against dF/F₀ values averaged across all red BG in (A). No correlation between spontaneous PC activity and surrounding BG activity was found, confirming the finding that spontaneous PC activity did not activate BG (R²=0.002 P=0.259). (G) Box-plot summarizing the correlations (R²) between spontaneously active PCs and surrounding BG (sPC-BG, blue, N=36 interactions from three mice), between spontaneously active BG and PCs encountered by spontaneous glial waves (sBG-PC, green, N=333 interactions from four mice), and between spontaneously active BG (sBG-sBG, red, 336 interactions from 4 mice). While spontaneous PC activity did not spread to surrounding BG, spontaneous glial wave activity consisting of active BG did spread to PCs, although with low dF/F₀ amplitude. The positive correlation for sPC→BG was significantly lower than that for sBG→PC (P=1.4 × 10⁻⁶) and sBG→PC was significantly lower than that of sBG→sBG (P=0.0305).