In the absence of medial septum (MS) region, we imitated its effect through a tonic depolarisation to represent in vivo background activity and an additional depolarisation corresponding arhythmic ACh release applied to all neurons and theta-range oscillatory hyperpolarizing current applied to PV+ interneurons only. The latter models the rhythmic disinhibition of CA1 observed in vivo. Here, we report how this induced regular theta activity in CA1 with heterogeneous phase response of different morphological types.