Ventilatory conditioning by self-stimulation in rats: A pilot study

This article describes an experimental attempt to condition breathing pattern in rats. In this experiment, a freely moving rat was first rewarded by an electrical stimulation of the medial forebrain bundle whenever inspiratory duration (TI) exceeded 300 ms. A bidirectional control was then used: TIs longer than 400 ms were rewarded, and then TIs shorter than 300 ms were rewarded. The frequency of TIs longer than 300 ms increased when this event was rewarded, further increased when TIs above 400 ms were rewarded, and decreased during reversal conditioning (TI < 300 ms). At the beginning of the experiment, stimulation caused increased arousal and motor activity, but after prolonged conditioning, the brain stimulation was associated with quiet wakefulness. Although the general procedure appears to be well-suited to the experimental study of voluntary breathing, some possible improvements are suggested for further, more extensive investigations.We are grateful to Professor Claude Gaultier and to Professor Vincent Bloch for their support, to Pascale Leblanc for her invaluable assistance, and to Gerard Dutrieux and Michel Vigouroux for their technical contribution. This work was supported by the Université de Paris-Sud (Grant AI-9023) and by the Institut National de la Sante et de la Recherche Médicale (CJF 89-09).