Encoding of Spatio-Temporal Input Characteristics by a CA1 Pyramidal Neuron Model
Figure 10
Mechanisms underlying somatic bursting.
A. Representative traces from the model (somatic, dendritic at 300 microns) showing the effect of mechanism blockade (90% reduction in conductance) on the generation of dendritic plateau potentials and somatic bursts using Protocol 3. A1. Blockade of NMDA currents results in complete elimination of dendritic plateau potentials as well as somatic bursting. Note that AMPA currents were increased to counteract excitability reduction from the NMDA blockade when each of the pathways was stimulated individually, indicating that dendritic plateau potentials are NMDA dependent. A2. Blockade of R-type currents (caR and caRH) severely reduces the appearance and width of dendritic plateau potentials as well as somatic bursting. A3–A5. Blockade of N-type, T-Type and L-type currents has a negligible effect on dendritic and somatic responses, indicating that these mechanisms do not significantly contribute to dendritic plateau potentials or somatic bursting. B. Dependence of dendritic plateau potentials and somatic bursting on the temporal offset between SC and PP inputs. Traces showing simultaneous stimulation (0 ms, B1) produce large, long-lasting plateau potentials in the dendrites which diminish in size and duration as the two inputs are separated in time (by 50 ms, B2 and 100 ms, B3). Somatic bursting follows the same trend.