Synchronization and knowledge of results in a ventilatory motor task.

The ability of healthy subjects to adopt a given value of inspiratory duration (TI) was examined in two different conditions: a knowledge condition in which subjects were informed of their performance on TI and synchronization of subjects' breathing rate to a periodic visual signal. The target value of TI was computed individually, by the same formula for all subjects in both procedures. 40 subjects were tested in a double-transfer design; each subject participated in two sessions 24 hr. apart. In addition to previous results showing better retention of the ventilatory task in subjects following the knowledge procedure after 24 hr., this study also shows better performance in this condition. No transfer could be evidenced, suggesting low similarity between the two tasks in spite of the fact that the resulting breathing patterns were nearly identical. The influence of the magnitude of the target on performance was also investigated.

Retention of ventilatory pattern learning in normal subjects.

Two procedures for training normal subjects to increase inspiratory duration (TI) were compared. In the first procedure (feedback), a visual signal informed subjects of their TI value just after the end of each inspiration; subjects were instructed to maintain TI for a set interval previously established by the experimenter. The second procedure (pacing) consisted of delivering a periodic signal to subjects and instructing them to adjust their respiratory frequency to this signal. All subjects participated in two identical sessions, 24 h apart. Comparison of performances between the two sessions provides evidence for a retention effect in feedback subjects only, suggesting the superiority of this method. Voluntary increase of TI during training induced a spontaneous increase of tidal volume, independent of any instruction. This increase in breathing amplitude cannot be explained in terms of chemical control of breathing.