Dorsal root ganglion is the primary affarent neuron transducting the sensory information. In recently years, more interests have been focused on the properties and chemosensitivity of the somata due to the following reasons: the somata possesses some properties as its central and peripheral terminals, and more importantly, the physiologically less firing neurons may arise spontaneous discharges because of decreased exciting threshold, increased excitability following somata or peripheral nerve damage. These...