Coordinate system used to describe the tuning of cNRTP neurons to saccades in three dimensions. The normalized optimal tuning vector, ê = (êx,êy, êz), which is found by fitting Eq. 6 to the data, is parametrized by polar angles φ (angle with positive y-axis in Listing’s plane; LP, shaded area) and ψ (torsional polar angle with LP).