Behavioural Effects of Electrical Stimulation in the Forebrain of the Pigeon

Abstract

AbstractActions belonging to the reproductive behaviour have been released by means of electrical stimulation in the forebrain of unanaesthetized, freely moving pigeons (Columba livia). The following behaviour items, which normally are closely associated with courtship behaviour, were obtained: the bowing action, preening movements - particularly displacement preening, the pecking and the nest demonstration. The different actions were released both in females and males but the aggressive bowing action was induced in considerably more males than females while the nest demonstration was observed in a higher frequency in the females. The positive sites of stimulation were concentrated in the preoptic nuclear complex. Solitary active points were located in nuclei bordering the preoptic area, such as the anterior hypothalamic, the anterior diencephalic paraventricular and the septal. The active zone bordered and partially overlapped the substrate for actions belonging to other categories of instinctive behaviour such as food and water intake and defence and escape. The rather restricted field for courtship actions extended medially up into the paleo-, neo- and hyperstriatum. The responses from the striatal level were generally less complete and intense than those from the more basal level. Stimulation in males at the preoptic and anterior hypothalamic level generally induced an intense bowing action with all normal components, and confrontation with adequate external stimuli released a complete aggressive action. The bowing could also be transformed into nest demonstration via displacement preening indicating a change in motivation from aggressiveness to sexual, which is a clear parallel to the introductory male courtship behaviour. The females also showed parallels to the precopulatory behaviour. The induced response was nest demonstration, preening movements - mainly displacement preening and pecking. The results show that in birds, as in mammals, it is mainly the preoptic area which takes part in the regulation of actions serving reproduction. Evidence has been produced that in birds striatal areas of the telencephalon are also involved in the coordination of such actions. The principle of organisation that can be traced in these experiments shows some interesting similarities to basic elements of animal behaviour and in a broad sense with the principles of the organisation of instinctive behaviour patterns according to TINBERGEN (1951).