A–F, 3D translational direction tuning for six example neurons with unimodal (A–C) and bimodal (D–F) spatial tuning. Preferred directions (computed by vector sum) were [azimuth, elevation] = [−60.3, 36.0°], [−82.4, −43.4°] and [−138.2, −63.2°] for the unimodal cells in A–C, respectively (DDI = 0.88, 0.86, and 0.88, respectively). The corresponding DDIs for the bimodal cells in D–F were 0.64, 0.65, and 0.79.