" ... Here we show that the voltage fluctuations associated with
dendrosomatic synaptic activity propagate significant distances
along the axon, and that modest changes in the somatic membrane
potential of the presynaptic neuron modulate the amplitude
and duration of axonal action potentials and, through a Ca21-
dependent mechanism, the average amplitude of the postsynaptic
potential evoked by these spikes.
These results indicate that
synaptic activity in the dendrite and soma controls not only the
pattern of action potentials generated, but also the amplitude of
the synaptic potentials that these action potentials initiate in local
cortical circuits, resulting in synaptic transmission that is a
mixture of triggered and graded (analogue) signals."
Shu Y, Duque A, Yu Y, Haider B, McCormick DA (2007) Properties of action-potential initiation in neocortical pyramidal cells: evidence from whole cell axon recordings. J Neurophysiol 97:746-60 [PubMed]
Shu Y, Hasenstaub A, Duque A, Yu Y, McCormick DA (2006) Modulation of intracortical synaptic potentials by presynaptic somatic membrane potential. Nature 441:761-5 [PubMed]