Horseradish peroxidase localization of the mylohyoid motoneurones in the rabbit.

Experiments were performed with anaesthetized (urethan and chloralose) spontaneously breathing rabbits. Horseradish peroxidase (HRP) was injected (1 mg) with a Hamilton syringe into the end of the sectioned mylohyoid nerve. The HRP-labelled neurones could be localized in the motor nucleus of the trigeminal nerve (N.

The respiratory response to magnetic stimulation of the cortex in the unanaesthetized baboon.

Transcranial magnetic stimulation has been used to study cortical input to the respiratory system in unanaesthetized baboons. Single magnetic pulse caused usually a short-latency excitation with subsequent inhibition in stimulated inspiratory phase and change in the amplitude and timing of the respiratory cycle. The results suggest that cortical information is processed by the medullary pattern generator.

The role of neural connections crossed at the cervical level in determining rhythm and amplitude of respiration in cats and rabbits.

The part played by crossed cervical pathways in determining respiratory rhythm and phrenic nerve amplitude was studied in rabbits and cats. The animals were anesthetized with halothane, paralyzed, vagotomized and mechanically ventilated. All decussating brain stem pathways were surgically interrupted.

Breuer-Hering reflexes in ketamine-induced apneustic breathing in the rabbit.

The effects of ketamine on the activities of the mylohyoid nerve (a branch of the Vth nerve) and of both phrenic nerves were investigated in rabbits anaesthetized with halothane, paralyzed and artificially ventilated. Intravenous administration of ketamine elicited a marked prolongation of the phrenic inspiratory discharge (without significantly affecting its amplitude) and a depression of the mylohyoid expiratory activity. An elimination of the volume-related input from the lungs ("no-inflation manoeuvre") or deflation elicited under these conditions typical apneustic pattern of breathing.

Motor nucleus of the V-th nerve and the control of breathing (Breuer-Hering reflexes and apneustic breathing).

Earlier studies from this department have demonstrated that neurones of the V-th nerve motor nucleus (NVmt) have oligosynaptic, inhibitory output to the inspiratory motoneurone pool being themselves under the influence of a polisynaptic input from vagal afferents. To check the hypothesis that NVmt is a part of the pneumotaxic mechanism, we studied the effects of pharmacological mictroblockade of the NVmt on Breuer-Hering reflexes in halothane-anaesthetized, paralyzed and artificially ventilated rabbits. Activities of NVmt neurones and phrenic nerve firing were recorded.