Patch clamp and imaging of intracellular [Ca2+] in 5 HTergic neurones in slice culture. A. Confocal image of EGFP-positive ventral raphe neurones (left panel), one of which was recorded in whole-cell configuration using a pipette solution containing Rhod-2 (centre panel; arrow indicates pipette tip). B. Representative recording from an EGFP-positive raphe neuron. Trains of action potentials (top trace) were triggered by injections of depolarizing current (lower trace). Note the prominent after-hyperpolarizations (arrowheads). C. Intracellular Ca2+ dynamics in a 5 HTergic neuron based on Rhod-2 fluorescence (top trace; fluorescence intensity in arbitrary units, AU). Repeated trains of action potentials (bottom trace) induced by current injections resulted in reproducible [Ca2+] increases.