Open AccessCalcium transients in dendrites of neocortical neurons evoked by single subthreshold excitatory postsynaptic potentials via low-voltage-activated calcium channels.
Author(s) -
Henry Markram,
Bert Sakmann
Publication year - 1994
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.91.11.5207
Subject(s) - excitatory postsynaptic potential , neocortex , dendritic spike , membrane potential , biophysics , postsynaptic potential , voltage dependent calcium channel , chemistry , neuroscience , soma , calcium , dendritic spine , biology , hippocampal formation , inhibitory postsynaptic potential , receptor , biochemistry , organic chemistry
Simultaneous recordings of membrane voltage and concentration of intracellular Ca2+ ([Ca2+]i) were made in apical dendrites of layer 5 pyramidal cells of rat neocortex after filling dendrites with the fluorescent Ca2+ indicator Calcium Green-1. Subthreshold excitatory postsynaptic potentials (EP-SPs), mediated by the activation of glutamate receptor channels, caused a brief increase in dendritic [Ca2+]i. This rise in dendritic [Ca2+]i was mediated by the opening of low-voltage-activated Ca2+ channels in the dendritic membrane. The results provide direct evidence that dendrites do not function as passive cables even at low-frequency synaptic activity; rather, a single subthreshold EPSP changes the dendritic membrane conductance by opening Ca2+ channels and generating a [Ca2+]i transient that may propagate towards the soma. The activation of these Ca2+ channels at a low-voltage threshold is likely to influence the way in which dendritic EPSPs contribute to the electrical activity of the neuron.