Effects of Intranasal Application of the Local Anaesthetic Xylocaine on Vestibulo-, Opto-Collic and Postural Reflexes of the Head, and on Tonic Immobility in Homing Pigeons: Implications for Experiments on Pigeon Homing

Abstract

Spraying lidocaine (Xylocaine), a local anaesthetic, into the nasal cavity of homing pigeons is a technique widely used to study the role of olfaction in pigeon homing. Studies in the laboratory revealed that Xylocaine suppressed vestibular and optokinetic nystagmus, roughly for as long as it suppressed olfaction, interfered with control of the head posture when the body was tilted in the sagittal plane, and prolonged tonic immobility. Amplitude and duration of both optokinetic and vestibular nystagmus were affected to the same extent. The effects are most probably caused by the drug's rapid absorption via the mucous membranes in the nasal cavity and its transport in the blood to brain structures involved in integrating vestibular and visual inputs. The results provide room for nonolfactory explanations of the manifold effects on pigeon homing following administration of local anaesthetics to the nasal chambers.