Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells. Export

@article{citeulike:5036514, abstract = {Morphological studies have provided ample evidence for synaptic connections between cerebellar Purkinje cells (PCs), but the functional properties of these synapses remain elusive. We report on direct recordings of synaptically connected PCs in mice cerebellar slices. In PCs filled with a fluorescent dye to aid axon visualization and postsynaptic target identification, presynaptic action potentials elicited unitary inhibitory postsynaptic currents in neighboring PCs in 10\% of potential connections tested. In 11 pairs, postsynaptic currents had a delay onset of 1.62 +/- 0.16 ms with respect to the presynaptic spike, a 10-90\% rise time of 2.20 +/- 0.33 ms, and a monoexponential decay with a time constant of 13.3 +/- 1.7 ms. Average values for peak current and variance-to-mean ratio were 55 +/- 14 and 30 +/- 3 pA, respectively. In contrast to the depressing nature of the synapse between PCs and deep cerebellar nuclei neurons, PC-PC synapses exhibited strong facilitation operating within a time window of a few milliseconds; paired-pulse ratios for 3- and 20-ms intervals were 1.79 +/- 0.18 and 1.01 +/- 0.14, respectively (n = 6). The facilitation is of presynaptic nature because it is accompanied by a decrease in failure rate. Trains of action potentials evoked in presynaptic varicosities volume-averaged calcium transients whose peak increased 1.7-fold as the frequency increased from 50 to 166 Hz. We suggest that PC-PC synapses are tuned for high fidelity of transmission during bursts of PC activity and that their operation in the cerebellar circuit modulates synchronized PC firing.}, author = {Orduz, D. and Llano, I.}, citeulike-article-id = {5036514}, citeulike-linkout-0 = {http://dx.doi.org/10.1073/pnas.0707489104}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/17965230}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=17965230}, day = {6}, doi = {10.1073/pnas.0707489104}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {axon, cerebellum, collateral, purkinje}, month = {November}, number = {45}, pages = {17831--17836}, posted-at = {2009-07-01 21:13:54}, priority = {2}, title = {Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells.}, url = {http://dx.doi.org/10.1073/pnas.0707489104}, volume = {104}, year = {2007} }

TY - JOUR ID - citeulike:5036514 L3 - citeulike-article-id:5036514 N2 - Morphological studies have provided ample evidence for synaptic connections between cerebellar Purkinje cells (PCs), but the functional properties of these synapses remain elusive. We report on direct recordings of synaptically connected PCs in mice cerebellar slices. In PCs filled with a fluorescent dye to aid axon visualization and postsynaptic target identification, presynaptic action potentials elicited unitary inhibitory postsynaptic currents in neighboring PCs in 10% of potential connections tested. In 11 pairs, postsynaptic currents had a delay onset of 1.62 +/- 0.16 ms with respect to the presynaptic spike, a 10-90% rise time of 2.20 +/- 0.33 ms, and a monoexponential decay with a time constant of 13.3 +/- 1.7 ms. Average values for peak current and variance-to-mean ratio were 55 +/- 14 and 30 +/- 3 pA, respectively. In contrast to the depressing nature of the synapse between PCs and deep cerebellar nuclei neurons, PC-PC synapses exhibited strong facilitation operating within a time window of a few milliseconds; paired-pulse ratios for 3- and 20-ms intervals were 1.79 +/- 0.18 and 1.01 +/- 0.14, respectively (n = 6). The facilitation is of presynaptic nature because it is accompanied by a decrease in failure rate. Trains of action potentials evoked in presynaptic varicosities volume-averaged calcium transients whose peak increased 1.7-fold as the frequency increased from 50 to 166 Hz. We suggest that PC-PC synapses are tuned for high fidelity of transmission during bursts of PC activity and that their operation in the cerebellar circuit modulates synchronized PC firing. IS - 45 JF - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 EP - 17836 TI - Recurrent axon collaterals underlie facilitating synapses between cerebellar Purkinje cells. VL - 104 SP - 17831 KW - axon KW - cerebellum KW - collateral KW - purkinje AU - Orduz, D AU - Llano, I PY - 2007/11/06/ UR - http://dx.doi.org/10.1073/pnas.0707489104 ER -