Neurostructures Activated in Pecking Pigeons and Marked with 14C-2-Deoxyglucose

14C-2-deoxyglucose autoradiographs were carried out in nine domestic pigeon brains to localize the sites of activity during an episode of repetitive pecking lasting for 60 min. This extended pecking was brought about either by a repeated dopaminergic apomorphine injection course or by an extended partial reinforcement conditioning training course lasting some 30 days. Forty brain structures were found labeled in the control, minimally (=virtually non-) pecking pigeons (K), 23 brain structures were exclusively labeled in the birds pecking upon Conditioning, while another 6 of them were also marked in apomorphine treated birds. Another 11 additional brain structures were exclusively labeled in the pigeons pecking upon Apomorphine treatment. We made out 25 brain structures as definitely not involved in the generation of either C or A pecking. Additionally we looked into the brain 14C markings of three birds pecking under Apomorphine in three kinds of sensory contexts: (1) darkness, which generally weakened the 14C brain marking but had only a few smaller specific effects; (2) deafness through cochlear ablation, which yielded a marking of the nuclei mesencephalici dorsales and a somewhat lesser labeling of the thalamic n. ovoidalis, but had no appreciable differential effect on forebrain markings, and (3) monocular viewing by covering one eye with an eye cap, which revealed an asymmetrical activation of a number of well-known visual brain structures, but nothing that was in any way unexpected.