Ultradian rhythm of circumnutations and oscillations of electrical potential

The blue line presents an ultradian (2.5 h) rhythm of circumnutations as a projection on the north-south (N-S) axis. The black and red lines show changes in the electric potential (maximum - depolarization, minimum - hyperpolarization) recorded by electrodes inserted at a depth of 1 mm on the opposite sides of the stem in the motor zone. The changes in the electric potential exhibit an ultradian rhythm with a period of ca. 2.5 h and differentiation of phases in the different areas on the stem at a given time. When circumnutations are long (over 4 cm) and the broadly elliptical bending in the motor zone is strong, depolarisation (highlighted in yellow in the film) occurs on the concave side of the stem and hyperpolarisation occurs on the opposite, convex side.