ACTION-POTENTIAL INITIATION AND BACKPROPAGATION IN NEURONS OF THE MAMMALIAN CNS

Most neurons in the mammalian CNS encode and transmit information via action potentials, Knowledge of where these electrical events are init iated and how they propagate within neurons is therefore fundamental t o an understanding of neuronal function. While work from the 1950s sug gested that action potentials are initiated in the axon, many subseque nt investigations have suggested that action potentials can also be in itiated in the dendrites, Recently, experiments using simultaneous pat ch-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 synapti c activation is powerful enough to elicit dendritic electrogenesis, Fu rthermore, 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 th e dendritic tree.