Model Design.

CA1 neurons were modelled using 25-compartments with the inclusion of NMDA, AMPA and GABA receptors. Note that in the cell model schematics, the basal dendrites are positioned upward and the apical dendrites downward, consistent with typical recording configurations. (A) Theta frequency network activity simulated using sinusoidal current injection. This generated a sinusoidal response at the soma with a peak-to-peak membrane potential of ∼10 mV (sub-panel ii, Scale bars represent 1 mV, 20 ms). Current injection was then given in combination with afferent synaptic input at 16 input phases. Example in sub-panel iii shows afferent inputs converging at an input phase of 90 degrees (Scale bars represent 2 mV, 10 ms). (B) Theta frequency network activity simulated using a patterned barrage of excitatory and inhibitory inputs. GABA inputs were clustered on the soma and on the most proximal apical and basal compartments (open circles). Glutamate and NMDA receptors were distributed throughout the apical dendrite including its branches (filled circles). Sub-panel ii shows the resulting sinusoidal theta frequency response measured at the soma (Scale bars represent 1 mV, 20 ms). Afferent synaptic inputs were then overlaid at 16 input phases. Example in sub-panel iii shows afferent inputs converging at an input phase of 90 degrees (Scale bars represent 2 mV, 10 ms). Somatic responses generated using current injection are comparable to those generated using a barrage of synaptic inputs.