Fig. 5.

“Exploratory” behavior. The graphs illustrate on expanded time scales the behavior of the axon shown in the previous figure. The red symbols and line indicate the changes in total side branch length—i.e., the summed length of all visible filopodia and side branches of the leading tip of the axon. Theblue symbols and trace indicate the principal axon length, i.e., the distance from a stable measuring point to the most distal tip of the body of the growth cone. Both measurements are normalized to the respective measurements made at the beginning of the sequence. Note the lack of net advance (blue trace) and the considerable “stationary” movement (redtrace). Negative numbers in either case indicate retractions with respect to the position at the onset of the observation period.