Fig. 9.

A and B: representative bursts from two different cells showing characteristic spike attenuation and depolarization during the burst. C: current injection in a bursting neuron showing lack of bursting when injecting 1.5× rheobase. D: current injection into the same bursting cell from C showing bursting when injection is coincident with spontaneous input to the cell. A–D: tic marks signify spikes that are part of a burst. E and F: representative traces showing plateau potentials (dashed lines) following a burst. G and H: representative response to three 1.8-ms current pulses (amplitude between 800 and 1000 pA, frequency of pulses increased from 25 to 100 Hz) designed to induce back-propagating action potentials and dendritic calcium currents. Plots are aligned to the last of the three pulses. The epoch between the dashed lines is where depolarization is expected to occur in a subset layer 5 bursting cells when the pulse frequency is above 100 Hz. None of the bursting cells or nonbursting cells in this study exhibited such behavior. In all plots, 0 mV and the resting membrane potential are labeled with gray lines.