CALCIUM SIGNALING COMPONENTS OF OSCILLATING INVERTEBRATE NEURONS IN VITRO

Abstract—We have studied the Ca2 dynamics of bursting– spiking neurons in the lobster stomatogastric ganglion. Neu-rons in this ganglion undergo spontaneous oscillations in membrane voltage with a period of 1–10 s in situ. We found that neurons isolated from the ganglion and filled with the fluorescent calcium indicator Fluo-4 show simultaneous changes of membrane potential and cytoplasmic Ca2 con-centration ([Ca2]I). These Ca 2 signals are highly heteroge-neous both in terms of amplitude and time constants. They showed variable spatial distributions with the soma exhibit-ing low and slow signals, and a region in the process with large and fast signals. Ca2 transients in the processes are dependent on exter-nal Ca2 and can be blocked by Co2, but not other, mor