Procedural memory trace for increased tidal volume can be demonstrated in healthy volunteers.

The minority of healthy subjects can (without previous learning) breathe at exactly double of their resting tidal volume on demand. The aim of the present study was to find whether this estimate of tidal volume value can be learned and at what speed. Basic spirometric values were measured by Oxycon B in 20 healthy volunteers. They learned in one day to breathe at double of the resting tidal volume twice for 3 min. The existence and duration of the memory trace was ascertained four times (three times on the same day, once three weeks later). This engram can be demonstrated on the day of learning after 1 or 2 trials of 3 min each. Three weeks later the memory trace is weak but still present. This fact means that a new breathing pattern can be learned. During learning and tests the subjects hyperventilate but no correlation was seen between learning ability and intensity of hyperventilation.