Distribution of Φmax values in the three types of descending neuron. A, Φmax values from brain POL-neurons with descending axons in the left connective. E-vector orientations (ipsilaterally descending, black; contralaterally descending, red) seem to be clustered around 154°, but the distribution is not significantly different from randomness (Rao's spacing test, p > 0.01). B, Φmax values from brain POL-neurons with descending axons in the right connective. Φmax values are clustered around 74°, but the distribution is not significantly different from randomness (Rao's spacing test, p > 0.1; same color code as in A). C, Φmax values of all SOG neurons (the red value is mirrored) descending through the left connective. Φmax values are clustered around 42° and 116°, but the distribution is not significantly different from randomness (Rao's spacing test, p > 0.1).