Fig. 4.

Two dopamine concentration transients in the OT of a male rat associated with the introduction of a receptive female to the test chamber and subsequent contact. A, A 4 sec trace of the electrochemical signal at the oxidation potential of dopamine (+0.6 V vs Ag/AgCl reference) converted to dopamine concentration using the in vitro calibration of the electrode after the experiment. The electrochemical scans confirmed to be dopamine by the cyclic voltammograms are indicated byopen circles. B, Cyclic voltammograms corresponding to the electrochemical signal at the times indicated by the arrows. The cyclic voltammograms verify that the changes in electrochemical signal during the two transients are attributable to the oxidation of dopamine (middle andright), whereas no changes in dopamine are apparent beforehand (left). The oxidative and reductive peaks of the dopamine transients are compared with those of dopamine obtained during the electrical stimulation of the dopamine fibers (dotted line, scaled to size). C, The video record of the experiment corresponding to the electrochemical signal at the times indicated by the arrows. The first dopamine transient coincided with the entrance of the female to the test chamber and was followed by immediate orientation of the male toward the female. The second transient was concurrent with the initial whisker contact between the rats and was followed by investigative sniffing of the female by the male.