As one of the most important second messengers, calcium in nerve cells plays a critical role in neuronal processes,
including excitability, neurotransmitter release, synaptic plasticity. Modulation of the calcium concentration is an
important means of regulating diverse neuronal functions. To evaluate the role of calcium, quantitative measurement of
cytosolic free calcium concentrations is necessary. There are several optical techniques that are available for
measurement of calcium in live cells. Laser scanning confocal microscopy and two-photon microscopy are two prevalent
techniques for their advantage in spatial resolution. In this paper, calcium in dorsal root ganglion neurons was imaged by
laser scanning confocal microscopy and two-photon microscopy with Fluo-3, a calcium specific fluorescence probe.
Both of spatial resolution and photobleaching, two common limitations of optical image modality, were compared
between laser scanning confocal microscopy and two-photon microscopy, respectively. Three dimension images showed
that laser scanning confocal microscopy and two-photon microscopy had not only similar lateral resolution but also
parallel vertical resolution. However, Laser scanning confocal microscopy had an advantage over the two-photon
microcopy in photobleaching. These results indicated that laser scanning confocal microscopy was more suitable than
two-photon microscopy to be applied in imaging calcium in dorsal root ganglion neurons with Fluo-3.