Somato-dendritic interactions underlying action potential generation in neocortical pyramidal cells in vivo.
Alain Destexhe, Erik Lang and Denis Paré

In: Computational Neuroscience. Trends in Research (edited by J. Bower), Plenum Press, New York, pp. 167-172, 1998.

Copy of the full paper (PDF)

By combining computational models with intracellular recordings of neocortical pyramidal cells in vivo, we provided a plausible explanation for our experimental observations on how action potential are controlled by IPSPs in these cells. Models and experiments suggest that IPSPs affect action potentials by two mechanisms: a shunt effect due to the opening of ion channels underlying the IPSPs, and a voltage-dependent effect by preventing dendritic Na+ channels to participate to the somatic spike. Further, we suggest that under conditions of synaptic activity that occurs during active states in vivo, the conductance shunt and the voltage-dependent effect of synaptic inputs do not provide favorable conditions for backpropagating action potentials.
Several movie files illustrate the dynamics of membrane potential in soma and dendrites in a simulated neocortical layer V pyramidal neuron. They are an excellent complement to the figures of the paper. The somatodendritic distribution of membrane potential is shown by colors in three cases of action potential generation:

backp_control.mpg Back-propagating action potential following current injection in the soma

backp_stim_dist.mpg Forward-propagating action potential following “distal” stimulation

backp_stim_prox.mpg Action potential following stimulation of “proximal” synapses. In this case, there is no action potential invasion in dendrites and the amplitude of the somatic spike is reduced (see paper)

See also the related article: Paré D, Lang EJ and Destexhe A. Inhibitory control of somatic and dendritic sodium spikes in neocortical pyramidal neurons in vivo: an intracellular and computational study. Neuroscience 84: 377-402, 1998.