The head-eye-body turning behavior induced by electrical or cholinergic stimulation of the pulvinar-lateralis posterior nucleus complex is not dependent on the catecholaminergic system.

Two experimental designs were developed in cats in order to analyze the role of the catecholaminergic system in the turning response evoked by cholinergic or electrical stimulation of the pulvinar-lateralis posterior nucleus complex (P-LP). Twenty one adult cats were employed. In one series of experiments, nine cats had a cannula implanted in one P-LP, and through it, apomorphine alone or mixed with carbachol were microinjected. The behavior was observed and the EEG was recorded. In the second experimental design, a cannula and bipolar electrodes were implanted unilaterally in the P-LP of nine cats, and a series of electrical stimulations were performed before and after 6-OHDA administration into the P-LP, and apomorphine was injected parenterally in order to induce turning behavior. Finally three cats received 16 micrograms of 6 OHDA into the P-LP, through a Hamilton syringe and no electrodes or cannula were implanted, to study the histological damage. No evidence of involvement of the catecholaminergic system was found in either of these two experimental series. These results contrast with what has been found in the nigrostriatal dopaminergic system, where an imbalance in dopamine concentration induces turning behavior. High doses (16 micrograms) of 6-OHDA induced minimal damage in the P-LP.