<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat"^^ . "Two-photon excitation fluorescence microscopy was combined with the patch-clamp technique to study the Ca2+ dynamics in dendrites and spines of spiny neurons of layer 4 of the somatosensory cortex in acute thalamocortical brain slices of young (P13-P15) rats. Back-propagating action potentials (bAPs) resulted in a transient rise in Ca2+ in all dendrites and spines tested, representing a global intracellular chemical signal about the activity of the cell. In contrast, synaptically evoked excitatory postsynaptic potentials (EPSPs) resulted in a synapse specific, local increase in Ca2+. Pairing both stimuli at different inter-stimulus intervals revealed a precisely tuned coincidence detection mechanism for pre- and postsynaptic activity, coded in the peak Ca2+ transient amplitude. Linear, sub- and supralinear summation of the Ca2+ transients, depending on the time interval and the order of bAP and EPSP, was found. Ca2+ influx was maximal when the action potential followed synaptic stimulation within less than 20 ms. The mechanism of maximal Ca2+ influx could be explained by the properites of the NMDA receptor channel, which was activated by binding glutamate during synaptic stimulation and subsequent relief of the Mg2+ block by the bAP. Coincidence detection was restricted to the synaptic contact and it did not depend on the distance of the contact from the soma. This temporally and spatially highly restricted coincidence detection mechanism, which emplyed the Ca2+ transient amplitude as a readout signal might serve as an input specific trigger for spike-timing dependent plasticity. Indeed potentiation of EPSPs to 150% of the baseline amplitude could be induced by pairing extracellular stimulation with bAPs within the coincidence detection interval. Reversing the order of the stimuli resulted in depression of the EPSP amplitude to 70%. Thus it was concluded that spiny neurons in layer 4 of the juvenile rat barrel cortex exhibit spike-timing dependent plasticity, which corresponded well to the Ca2+ code used by their spines for coincidence detection."^^ . "2002" . . . . . . . . "Thomas"^^ . "Nevian"^^ . "Thomas Nevian"^^ . . . . . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat (PDF)"^^ . . . "Thesis_Nevian_final.pdf"^^ . . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat (Other)"^^ . . . . . . "small.jpg"^^ . . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Calcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat (Other)"^^ . . . . . . "lightbox.jpg"^^ . . "HTML Summary of #3249 \n\nCalcium dynamics in dendrites and spines of spiny neurons in the somatosensory ‘barrel’ cortex of the rat\n\n" . "text/html" . . . "530 Physik"@de . "530 Physics"@en . .