title: In vivo dendritic calcium dynamics in deep-layer cortical pyramidal neurons.
abstract: Dendritic Ca2+ action potentials in neocortical pyramidal neurons have been characterized in brain slices, but their presence and role in the intact neocortex remain unclear. Here we used two-photon microscopy to demonstrate Ca2+ electrogenesis in apical dendrites of deep-layer pyramidal neurons of rat barrel cortex in vivo. During whisker stimulation, complex spikes recorded intracellularly from distal dendrites and sharp waves in the electrocorticogram were accompanied by large dendritic [Ca2+ ] transients; these also occurred during bursts of action potentials recorded from somata of identified layer 5 neurons. The amplitude of the [Ca 2+] transients was largest proximal to the main bifurcation, where sodium action potentials produced little Ca2+ influx. In some cases, synaptic stimulation evoked [Ca2+] transients without a concomitant action potential burst, suggesting variable coupling between dendrite and soma.
authors.affiliation: Biological Computation Research Department, Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974, USA. fritjof@physics. bell-labs.com
authors.forename: F
authors.initials: F
authors.lastname: Helmchen
authors.forename: K
authors.initials: K
authors.lastname: Svoboda
authors.forename: W
authors.initials: W
authors.lastname: Denk
authors.forename: D W
authors.initials: DW
authors.lastname: Tank
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism*; D066298:In Vitro Techniques; D017966:Pyramidal Cells / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002118:Calcium