Nature Neuroscience
2, 989 - 996 (1999)
doi:10.1038/14788
In vivo dendritic calcium dynamics in deep-layer cortical pyramidal
neuronsFritjof Helmchen1, Karel Svoboda2, Winfried Denk1
& David W. Tank11
Biological Computation Research Department, Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974, USA
2
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
Correspondence should be addressed to Fritjof Helmchen fritjof@physics.bell-labs.comDendritic 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.
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