We recorded more than 300 pairs of Purkinje cells from Crus 1 and Crus 2 in awake wild-type animals or mice lacking gap-junction protein delta-2 (GJD2; formerly called connexin36) -/- knock-out mice results (Long et al. 2002; De Zeeuw et al. 2003). We found that Gjd2 is essential for consistent delays in complex spike activity during the same or successive olivary oscillation cycles, highlighting the impact of coupling in the olivocerebellar system on oscillatory pattern formation in ensembles of Purkinje cells.