Pachoud, B;
Sharma, P;
Bergerot, A;
Marcaggi, P;
Knöpfel, T;
(2014)
Quantification of the density of cooperative neighboring synapses required to evoke endocannabinoid signaling.
Neuroscience
, 256
412 - 425.
10.1016/j.neuroscience.2013.10.041.
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Abstract
The spatial pattern of synapse activation may impact on synaptic plasticity. This applies to the synaptically-evoked endocannabinoid-mediated short-term depression at the parallel fiber (PF) to Purkinje cell synapse, the occurrence of which requires close proximity between the activated synapses. Here, we determine quantitatively this required proximity, helped by the geometrical organization of the cerebellar molecular layer. Transgenic mice expressing a calcium indicator selectively in granule cells enabled the imaging of action potential-evoked presynaptic calcium rise in isolated, single PFs. This measurement was used to derive the number of PFs activated within a beam of PFs stimulated in the molecular layer, from which the density of activated PFs (input density) was calculated. This density was on average 2.8μm in sagittal slices and twice more in transverse slices. The synaptically-evoked endocannabinoid-mediated suppression of excitation (SSE) evoked by ten stimuli at 200Hz was determined from the monitoring of either postsynaptic responses or presynaptic calcium rise. The SSE was significantly larger when recorded in transverse slices, where the input density is larger. The exponential description of the SSE plotted as a function of the input density suggests that the SSE is half reduced when the input density decreases from 6 to 2μm. We conclude that, although all PFs are truncated in an acute sagittal slice, half of them remain respondent to stimulation, and activated synapses need to be closer than 1.5μm to synergize in endocannabinoid signaling. © 2013 The authors.
| Type: | Article |
|---|---|
| Title: | Quantification of the density of cooperative neighboring synapses required to evoke endocannabinoid signaling |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.neuroscience.2013.10.041 |
| Publisher version: | http://dx.doi.org/10.1016/j.neuroscience.2013.10.0... |
| Language: | English |
| Additional information: | This work is licensed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivativeWorks 3.0 license. You are free to share (copy, distribute and transmit the work), but you must attribute the author, you may not use this work for commercial purposes and you may not alter, transform, or build upon this work and distribute any derivative works you create under a similar license. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1468939 |
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