Proximal Persistent Na+ Channels Drive Spike Afterdepolarizations and Associated Bursting in Adult CA1 Pyramidal Cells

摘要: In many principal brain neurons, the fast, all-or-none Na+ spike initiated at proximal axon is followed by a slow, graded afterdepolarization (ADP). The ADP critically important in determining firing mode of neurons; large ADPs cause neurons to fire bursts spikes rather than solitary spikes. Nonetheless, not much known about how and where are initiated. We addressed these questions adult CA1 pyramidal cells, which manifest conspicuous somatic an associated propensity for bursting, using sharp patch microelectrode recordings acutely isolated hippocampal slices single neurons. Voltage-clamp commands mimicking waveforms evoked transient currents that declined quickly after but were substantial sustained aftercurrents. Drugs blocked persistent current ( I NaP), markedly suppressed aftercurrents, as well bursting. Ca2+ aftercurrents smaller, reducing them had no noticeable effect on ADPs. Truncating apical dendrites affected neither nor modes Application NaP blockers truncated or their focal application region intact whereas distal did not. conclude generated predominantly channels located near soma. Through this action, determines output cells.