SIMULATIONS OF INTRINSICALLY BURSTING NEOCORTICAL PYRAMIDAL NEURONS

Neocortical layer 5 intrinsically bursting (IB) pyramidal neurons were simulated using compartment model methods. Morphological data as well as target neurophysiological responses were taken from a series of pu blished studies on the same set of rat visual cortex pyramidal neurons (Mason, A. and Larkman, A. J., 1990. J. Neurosci. 9, 1440-1447; Larkm an, A. J. 1991. J. Corny. Neurol. 306, 307-319). A dendritic distribut ion of ion channels was found that reproduced the range of in vitro re sponses of layer 5 IB pyramidal neurons, including the transition from repetitive bursting to the burst/tonic spiking mode seen in these neu rons as input magnitude increases. In light of available data, the sim ulation results suggest that in these neurons bursts are driven by an inward flow of current during a high threshold Ca2+ spike extending th roughout both the basal and apical dendritic branches.