Voltage dependence of the current that is modulated associatively or differentially, compared with the current that is modulated nonassociatively by serotonin. (A) Graph of the Pre–Post difference current (corrected for leakage) during 20 and 40 mV depolarizing pulses in the paired and unpaired SN, and then measured again in all neurons after adding 10−4 M serotonin to the bath. (B) Graph of the current that is modulated differentially (Paired−Unpaired) as a function of voltage. The shape of that curve is very similar to the curve for the current that is modulated by serotonin, indicating that those currents have similar voltage dependence in this range.
