Glutamate Mediated Astrocytic Filtering of Neuronal Activity
Figure 5
Frequency dependent astrocytic response to neuronal activity.
A, Ca2+ traces of two selected neurons (in red), showing stimulated activity according to a random multi-frequency protocol, and seven selected astrocytes (in green) showing frequency dependent [Ca2+]i elevations in response to neuronal activity. Experiments were performed in the presence of neuronal AMPAR and NMDAR/kainate antagonists. B, Ca2+ traces of same cells and stimulation protocol as in A, showing no astrocytic [Ca2+]i elevations in the presence of neuronal AMPAR and NMDAR/kainate antagonists, and astrocytic mGluR1 and mGluR5 antagonists. For each electrical stimulation frequency, single-cell astrocytes responsivenesses were very variable. Their distribution for the experiment displayed in A is shown in C, Increasing the stimulation frequency leads to increases in average astrocyte responsivenesses but it also increased responsiveness variability. D, Astrocytic population responsiveness versus stimulation frequency. Grey empty circles are population responsivenesses for experiments performed with NMDAR & AMPAR but without (astrocytic) mGluR antagonists (n = 284). Corresponding mean result, standard errors (black circles and bars), and sigmoid fit (black dashed line) are also illustrated. Turquoise empty squares are population responsivenesses obtained in the presence of both NMDAR & AMPAR and mGluR antagonists (n = 239). Corresponding mean results and standard errors and linear fit are shown as blue squares (with bars and dashed blue line, respectively).