@article {45912, title = {Determinants of voltage attenuation in neocortical pyramidal neuron dendrites.}, journal = {J Neurosci}, volume = {18}, year = {1998}, month = {1998 May 15}, pages = {3501-10}, abstract = {

How effectively synaptic and regenerative potentials propagate within neurons depends critically on the membrane properties and intracellular resistivity of the dendritic tree. These properties therefore are important determinants of neuronal function. Here we use simultaneous whole-cell patch-pipette recordings from the soma and apical dendrite of neocortical layer 5 pyramidal neurons to directly measure voltage attenuation in cortical neurons. When combined with morphologically realistic compartmental models of the same cells, the data suggest that the intracellular resistivity of neocortical pyramidal neurons is relatively low ( approximately 70 to 100 Omegacm), but that voltage attenuation is substantial because of nonuniformly distributed resting conductances present at a higher density in the distal apical dendrites. These conductances, which were largely blocked by bath application of CsCl (5 mM), significantly increased steady-state voltage attenuation and decreased EPSP integral and peak in a manner that depended on the location of the synapse. Together these findings suggest that nonuniformly distributed Cs-sensitive and -insensitive resting conductances generate a "leaky" apical dendrite, which differentially influences the integration of spatially segregated synaptic inputs.

}, keywords = {Animals, Cesium, Chlorides, Computer Simulation, Dendrites, Electric Conductivity, Electric Impedance, Excitatory Postsynaptic Potentials, Membrane Potentials, Models, Neurological, Neocortex, Patch-Clamp Techniques, Pyramidal Cells, Rats, Rats, Wistar}, issn = {0270-6474}, author = {Stuart, G and Spruston, N} } @article {45923, title = {Action potential initiation and backpropagation in neurons of the mammalian CNS.}, journal = {Trends Neurosci}, volume = {20}, year = {1997}, month = {1997 Mar}, pages = {125-31}, abstract = {

Most neurons in the mammalian CNS encode and transmit information via action potentials. Knowledge of where these electrical events are initiated and how they propagate within neurons is therefore fundamental to an understanding of neuronal function. While work from the 1950s suggested that action potentials are initiated in the axon, many subsequent investigations have suggested that action potentials can also be initiated in the dendrites. Recently, experiments using simultaneous patch-pipette recordings from different locations on the same neuron have been used to address this issue directly. These studies show that the site of action potential initiation is in the axon, even when synaptic activation is powerful enough to elicit dendritic electrogenesis. Furthermore, these and other studies also show that following initiation, action potentials actively backpropagate into the dendrites of many neuronal types, providing a retrograde signal of neuronal output to the dendritic tree.

}, keywords = {Action Potentials, Animals, Central Nervous System, Neurons}, issn = {0166-2236}, author = {Stuart, G and Spruston, N and Sakmann, B and H{\"a}usser, M} } @article {45913, title = {Activity-dependent action potential invasion and calcium influx into hippocampal CA1 dendrites.}, journal = {Science}, volume = {268}, year = {1995}, month = {1995 Apr 14}, pages = {297-300}, abstract = {

The temporal and spatial profile of activity-evoked changes in membrane potential and intracellular calcium concentration in the dendrites of hippocampal CA1 pyramidal neurons was examined with simultaneous somatic and dendritic patch-pipette recording and calcium imaging experiments. Action potentials are initiated close to the soma of these neurons and backpropagate into the dendrites in an activity-dependent manner; those occurring early in a train propagate actively, whereas those occurring later fail to actively invade the distal dendrites. Consistent with this finding, dendritic calcium transients evoked by single action potentials do not significantly attenuate with distance from the soma, whereas those evoked by trains attenuate substantially. Failure of action potential propagation into the distal dendrites often occurs at branch points. Consequently, neighboring regions of the dendritic tree can experience different voltage and calcium signals during repetitive action potential firing. The influence of backpropagating action potentials on synaptic integration and plasticity will therefore depend on both the extent of dendritic branching and the pattern of neuronal activity.

}, keywords = {Action Potentials, Animals, Calcium, Calcium Channels, Dendrites, Ion Channel Gating, Neuronal Plasticity, Patch-Clamp Techniques, Pyramidal Cells, Rats, Rats, Wistar, Sodium Channels, Synapses, Tetrodotoxin}, issn = {0036-8075}, author = {Spruston, N and Schiller, Y and Stuart, G and Sakmann, B} } @article {45892, title = {Probing dendritic function with patch pipettes.}, journal = {Curr Opin Neurobiol}, volume = {5}, year = {1995}, month = {1995 Jun}, pages = {389-94}, abstract = {

Most neurons in the CNS have complex, branching dendritic trees, which receive the majority of all synaptic input. As it is difficult to make electrical recordings from dendrites because of their small size, most of what is known about their electrical properties has been inferred from recordings made at the soma. By taking advantage of the higher resolution offered by improved optics, it is now possible to make patch-pipette recordings from the dendrites of neurons in brain slices under visual control. This new technique promises to provide valuable new information concerning dendritic function.

}, keywords = {Animals, Dendritic Cells, Electrophysiology, Hippocampus, Patch-Clamp Techniques}, issn = {0959-4388}, author = {Stuart, G and Spruston, N} }