[Importance of the orbitofrontal cortex in the development of morphine analgesia]

The development of morphine-induced analgesia before and after ablation of the orbitofrontal cortex of the brain (OFC) was studied in behavioural experiments on adult cats. The antinociceptive effect of morphine was shown to increase significantly after ablation of OFC. The enhancement of the analgesic effect of morphine following OFC ablation may be explained by a decrease of the tonic inhibitory influence of OFC on neurons of the brain antinociceptive system. Different effects of OFC and the somatosensory cortex on the brain antinociceptive system are discussed.