ACTIVITY-DEPENDENT CHANGES IN THE INTRINSIC-PROPERTIES OF CULTURED NEURONS

Learning and memory arise through activity-dependent modifications of neural circuits. Although the activity dependence of synaptic efficacy has been studied extensively, less is known about how activity shapes the intrinsic electrical properties of neurons. Lobster stomatogastri c ganglion neurons fire in bursts when receiving synaptic and modulato ry input but fire tonically when pharmacologically isolated. Long-term isolation in culture changed their intrinsic activity from tonic firi ng to burst firing. Rhythmic stimulation reversed this transition thro ugh a mechanism that was mediated by a rise in intracellular calcium c oncentration. These data suggest that neurons regulate their conductan ces to maintain stable activity patterns and that the intrinsic proper ties of a neuron depend on its recent history of activation.