Fig. 6.

A 20 min exposure to low concentrations of nicotine desensitizes the slow component of current from VTA DA and non-DA wild-type neurons. Responses to pressure applications of ACh (arrows) are shown for a VTA DA neuron (A) and for a non-DA neuron (B) in the absence (a) and presence (b) of 80 nm nicotine (Nic). The (a) −(b) subtraction shows the net nicotine-desensitized current. C, The average time course of desensitization is shown in response to 80 nm nicotine for the slow component of current from VTA DA neurons (▪; n = 7) and non-DA neurons (○; n = 10). Calibration: 25 pA, 1 sec.