| Abstract No.: | B-B2031 |
| Country: | Canada |
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| Title: | GLIA DECODE DIFFERENCES IN NEURONAL ACTIVITY TO GUIDE SYNAPTIC STRENGTH |
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| Authors/Affiliations: | 1 Keith Todd*; 1 Richard Robitaille;
1 Université de Montréal, QC, Canada
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| Content: | Glial cells detect changes in frequency of synaptic activity and, as a result, influence the outcome of various forms of synaptic plasticity. However, induction of synaptic plasticity does not solely rely on frequency, but also on the pattern of activity. We, therefore, investigated the impact of different patterns of neuronal activity on glial calcium signaling and the subsequent impact of glial calcium signaling on synaptic function. Here we show that glia decode the pattern of synaptic activity, and provide context-dependent feedback to determine the direction of synaptic plasticity. We imaged glial calcium elevations using Fluo-4 AM following evoked nerve activity and correlated these responses with post-tetanic plasticity. We observed single glial calcium responses during continuous synaptic activity correlated with short-term post-tetanic potentiation, while bursts of activity were associated with oscillations in glial calcium and were correlated with depression. Perturbation of glial cell calcium excitability by blocking elevations in glial calcium during evoked synaptic activity perturbed both forms of short-term plasticity. This was done using specific photolysis of caged BAPTA (diazo-2) in glia. To investigate the underlying mechanisms of this glial-dependent modulation we used caged calcium (NP-EGTA) to directly activate glial cells. Through the use of pharmacology and knockout animals we uncovered a balance of potentiating A2A, and inhibitory A1 adenosine receptors, that modulates synaptic strength. These results demonstrate that glia decode synaptic information in a pattern-dependent manner and provide context-dependent, bidirectional feedback to synapses. |
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