Fig. 3. Mathematical model of unc-23 behavior. (A) Representative track of a simulated unc-23 mutant in a radial gradient. Note that the simulated worm had a clockwise turning bias (7 deg. s^–1) and made a counterclockwise spiral, as do real unc-23 mutants (Fig. 1Bii). The gradient peak is indicated by the plus sign. Color represents time (see color scale). Pirouette initiation events are indicated by orange crosses superimposed on the magnified track within the inset. (B) Population behavior of simulated unc-23 worms in a radial gradient. The track of one simulated worm is highlighted in black; all other tracks are gray (N=50). Each simulated worm had a right-handed turning bias and made a left-handed spiral. The gradient peak is indicated by intersection of dotted lines. Simulations in A and B were started near the asterisks.