The last effect of circular current arising from helical MOs was explained by realizing that the flow of the current density arises from the gradient across a nodal plane. The circularity is not tied directly to the helicality of the MO, but as ψa and ψ b will have opposite chirality by symmetry, the gradient across the nodal plane of ψa will not be suppressed by the nodal plane of ψ b as we saw in 2.