Effects of forebrain lesions on spawning behaviour in the male goldfish.

Lesions were stereotaxically placed in medial nuclei of the ventral telencephalon and preoptic area of male goldfish. Only lesions in the area ventralis telencephali pars supracommissuralis (Vs) and posterior pars ventralis (pVv) were effective in reducing the proportion of males spawning, as compared to sham groups, both 5 days (Experiment 1) and up to 4 weeks (Experiment 2) postoperatively. Spawning consistency over 7 weekly tests was negatively correlated with the volume of Vs-pVv destruction. Two-thirds of Vs-pVv lesioned males spawned on at least one of their weekly tests, with latencies for the onset of each courtship behaviour similar to those of control fish, partial performance of the spawning sequence was rare. These results suggest that lesion of the supracommissural telencephalon (Vs-pVv region) blocks the initiation of spawning behaviour in the male goldfish, perhaps by lowering reproductive motivation specifically or by interfering with the perception of sexual, particularly olfactory, cues.