Time 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 as a function of time during the 500 msec depolarizing pulse in the paired and unpaired SN, and then measured again in both neurons after adding 10−4 M serotonin to the bath. The response to serotonin would be expected to have similar properties in both neurons, which were, therefore, averaged to provide a better estimate. (B) Graph of the current that is modulated differentially (Paired−Unpaired) as a function of time. 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 time dependence in this range.
